Abstracts old doctoral theses

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Bwire, J.M.N. 2002

Feeding strategies for dual-purpose cattle in semi-arid areas of central Tanzania. (June)

Bwire, J.M.N

Abstract

This thesis presents studies on the influence of pre-weaning management systems and dry season feeding regimes on post-weaning performance of improved zebu heifers (Paper I), the effect of supplementary feeding strategies before and after calving on the performance of dual- purpose cows (Paper II ) and an evaluation of feed resources that can be utilised by small holder farmers under a zero grazing system (Paper III- V). The experiments were carried out at Livestock Production Research Institute (LPRI), Mpwapwa, Tanzania on stall- fed cows, although heifers were allowed to graze during the wet season.

In Paper I pre-weaning management (artificial or restricted suckling with or without supplementation) had no influence on the post-weaning performance of heifers. A post-weaning feeding regime with concentrate supplementation of 1 kg DM per day (13 MJ/kgDM, 160-200g CP/kgDM) during the dry season improved the performance of the heifers to 19 months and 203
kg as age and weight at onset of puberty.

In Paper II cows on the high plane of nutrition produced more milk than cows on the low plane of nutrition, while intake of hay was similar and tended to decrease towards calving but increased again after calving. Liveweight change and body condition differed between treatments only after calving.

In Paper III harvesting maize tops at grain maturity and 3 weeks later yielded higher biomass of tops, higher crude protein, digestibility and metabolisable energy, and lower acid and neutral detergent fibre. The potential nutritive value was higher in maize tops stored in a shed compared to other methods. Dry matter intake and milk yield were higher on grass hay and green maize tops than maize stovers after normal grain harvest.

In Paper IV the most available and highest yielding grasses were used to formulate rations with two grass species in a 50:50 ratio. The ration with Cenchrus ciliaris and Cynadon plectostachyus had the highest digestibility, energy and protein, and cows produced more milk when on this
ration. In Paper V, when two levels (100% or 50%) of Acacia tortilis and Fadherbia albida pods in the concentrate mixture was compared as protein supplements, milk yield differed between treatments and an unpleasant odour was found in milk with 100% Acacia tortilis.

Key words: Improved zebu heifers, growth, puberty, dual-purpose cows, concentrate supplementation, feeding strategies, feed intake, milk yield, milk quality, tropical grasses, tree pods, body weight, body condition, maize tops, biomass, feed conservation

Author's address: Julius M.N.Bwire, Livestock Production Research Institute, Mpwapwa, P.O. Box 202, Mpwapwa, Tanzania.

Doctors dissertation. Distribution: Swedish University of Agricultural Sciences (SLU), Department of Animal Nutrition & Management P.O. Box 7024, 750 07 Uppsala, Sweden
ISSN 1401-6249, ISBN 91-576-6196-0

Agenäs, S. 2002

Regulation of milk production in cows selected for different milk fat content with special reference to transition periods. (June)

Agenäs, S

Abstract

The general aim of the present work was to study factors that influence performance of the dairy cow during periods of elevated metabolic strain. Cows selected for high or low milk fat content were used and milk yield composition, feed intake, energy balance, metabolic and hormonal factors were studied . Lactating dairy cows are critically dependent on the provision of nutrients for milk synthesis in order to maintain milk production. These nutrients can be of feed origin or from mobilised body tissues. When feed intake does not cover the requirements for milk production, for example in early lactation, the metabolism is directed toward mobilisation of body tissues.

Three experiments were included in this thesis. In the first experiment three groups of cows received different amounts of a total mixed ration during the dry period, in order to create groups of cows with different body condition at the onset of the lactation. In the second study changes in metabolism and milk production during and after a short period of feed deprivation were studied. The third study covered the change from winter-feeding to summer pasture in combination with dietary fat supplementation.

The results presented here show that the differences in milk production between the selection lines were less pronounced, or non-existing, when cows were subjected to different kinds of metabolic challenges. Thus, instead of exaggerating differences in nutrient partitioning the two selection lines became more alike. Selection for altered milk fat concentration induces changes in several physiological systems and in these studies it was not possible to isolate any key parameters with a superior impact on the differences in milk composition. We found that cows selected for high milk-fat content respond with higher insulin release when plasma glucose is elevated. Cows selected for low milk fat content showed a higher concentration of conjugated linoleic acids (CLA) in milk, in response to unsaturated fat in the diet. CLA is of specific interest, since it has been shown to possess health promoting properties, e.g. anticarcinogenity. It may be hypothesised that the difference in CLA between the selection lines was caused by a higher activity of mammary D 9-desaturase in low fat indexed cows.

Cows with high body condition at parturition showed a higher level of energy wasting than cows of moderate or low body condition. A high feed intake during the dry period is not beneficial either for the cow or the production economy which underlines the recommendation to avoid a high body condition at parturition. During the dry period the plasma concentration of the peptide leptin was related to feed intake and presumably also to adiposity. After parturition the leptin level was low and not related to body condition score or energy balance. It was therefore suggested that the drop seen in plasma leptin was caused by the lactation itself.

Keywords: b -hydroxybutyrate, conjugated linoleic acids, cortisol, dry matter intake, dry period, energy balance, feed deprivation, glucose challenge, insulin, leptin, metabolism, milk composition, milk fatty acids, milk production, non-esterified fatty acids, postparturient, selection line

Author's address: Sigrid Agenäs, SLU, Department of Animal Nutrition and Management, Kungsängen Research Centre, SE-753 23 Uppsala, Sweden.

Doctoral thesis. Distribution: Swedish University of Agricultural Sciences (SLU), Department of Animal Nutrition and Management, P.O. Box 7024, 750 07 Uppsala, Sweden

ISSN 1401-6249, ISBN 91-576-6186-3

Stahl-Hogberg, 2002

Improved feeding systems leading to higher milk yield for Indian dairy buffaloes. (May)

Ståhl Högberg, M

Abstract

Water buffaloes account for more than half of the Indian milk production, but their productivity is low. One of the major constraints is the sub-optimal feeding, characterised by a high inclusion of straw and expensive concentrate. Even in areas with a seasonal abundance of fodder, the amount of green forage given to the animals is too low to sustain a high milk yield. Improved feeding systems at farm level would increase the milk yield and decrease the production cost.

The objective of this thesis is to link the specific details of animal science with the overall picture of managing dairy animals in farmers' lives.

The specific research problems investigated in this thesis are dairy buffalo nutrient requirements, utilisation of feed resources and farmers' views on feeding and feeds, and how they described the possibilities and constraints to improve milk production.

In a quantitative study, farmers in two areas in Hisar district (rainfed/irrigated) were interviewed. The farmers with access to irrigation were able to supply their buffaloes with more green feeds than the farmers in the rainfed area.

The current feeding systems practised by the farmers could not sustain a high milk yield and the cost of production was very high due to a large amount of expensive concentrate in the diet. None of the interviewed farmers practised ensiling of surplus fodder, and thus they were forced to feed only straw and concentrate during the dry seasons (May and October), which further hampered the milk production potential and increased the cost of production.

The qualitative study in Punjab revealed that lack of formal knowledge regarding feeding, feeds and management of buffaloes was the most important reasons as to why buffalo farmers did not try silage making. The lack of knowledge could be a result of limited contact with the extension services.

Farmers described dairy farming as important because it provided the household with milk, income from milk and feed sales. Maximising production was not seen as a priority to the farmers I met.

Key words: water buffalo, nutrient requirements, resources, milk production, quantitative, qualitative, interviews.

Author's address: Mikaela Ståhl Högberg, Swedish University of Agricultural Sciences (SLU), Department of Animal Nutrition & Management P.O. Box 7024, 750 07 Uppsala, Sweden

Licentiate's dissertation. Distribution: Swedish University of Agricultural Sciences (SLU), Department of Animal Nutrition & Management P.O. Box 7024, 750 07 Uppsala, Sweden
ISSN 0347-9838, ISRN SLU-HUV-R-252-SE

Nguyen Thi Mui. 2001.

Feeding systems for goats based on foliages and whole sugar cane. (December)

Nguyen Thi Mui

Abstract

This thesis presents studies on the use of whole sugar cane and foliages from Jackfruit (Artocapus heterophyllus) and Flemingia (Flemingia macrophylla) in diets of growing and lactating goats. The studies were carried out at the Goat and Rabbit Research Centre in Sontay, Hatay, Vietnam. In Paper I the effect of cutting size, splitting lengthwise and removal of the rind of the sugar cane was studied. The processing methods had no affect on intake of sugar cane leaves and tops, but chopping cane stalks into small 1-3 cm slices improved feed intake. Using chopped whole sugar cane for feeding growing goats at 30 % of dry matter (DM) of the diet increased live weight gain by 30 % and the feed utilisation efficiency was the best among the diets tested.

In Paper II and III, the foliages of Jackfruit and Flemingia were evaluated as sources of protein, replacing the protein of rice bran-soya bean concentrates in the diet of growing and lactating goats. For Jackfruit a replacement level of 0 to 50 % of the crude protein (CP) gave similar live weight gain (P>0.05). Jackfruit can provide up to 100 % of the CP requirement but with a decline in the performance. Increasing levels of Flemingia resulted in decreasing DM intake and growth (P>0.05). The best growth rates were achieved when Flemingia replaced 26 % of the CP in the concentrate (17 % of DM). For lactating goats, replacement with Jackfruit at the level of 40 % of the CP in the concentrate gave a similar milk yield, milk quality and feed conversion ratio as the control diet. Increasing Flemingia resulted in decreasing milk yield and the highest milk yield was achieved in the control group. Flemingia showed a poor potential as a supplement and replacement levels should not exceed 20 % of CP in a concentrate.

When the nitrogen (N) balance was studied more closely (Paper IV) it was found that Jackfruit foliage has a high potential as a protein supplement to sugar cane diets, and can improve feed intake and give a positive nitrogen balance in goats. Flemingia foliage as a protein supplement in the dry season was more efficient than in wet season, but in general Flemingia had a lower potential as a supplement than Jackfruit. Supplementation with 5 g of polyethylene glycol (PEG) to the Jackfruit diet increased digestibility and N retention while supplementing a diet with Flemingia reduced digestibility and N retention.

Key words: Sugar cane leaves, Tops, Stalks, Chopped whole sugar cane, Jackfruit, Flemingia, Protein, Concentrate, Growing goats, Lactating goats, Polyethylene glycol.

Author's address: Nguyen Thi Mui, National Institute of Animal Husbandry, Chem, Thuyphuong, Hanoi, Vietnam

Distribution: Swedish University of Agricultural Sciences, Department of Animal Nutrition and Management, P.O. Box 7024, SE-750 07 Uppsala, Sweden.

ISSN 1401-6249, ISBN 91-576-5825-0

Mai Van Sanh, 2001

Effects of feeding level and forage/concentrate ratio on milk production and performance of crossbred lactating cows.(December)

Mai Van Sanh

Abstract

Six experiments were conducted to evaluate the response of lactating cows to different feeding levels and ration formulation on milk production and performance. Altogether 124 crossbred cows (Holstein Friesian and Vietnamese Local Yellow) were included in the studies with a pre-experimental period of the first 8 weeks after calving and the start of the studies from the 9th week of lactation. In the first 5 experiments, cows were divided into groups using a randomized block design according to the milk yield of the previous eight weeks. In the last experiment, cows were blocked according to the milk yield of the previous eight weeks and divided into 4 homogenous groups with a Latin square design.

The daily milk yield and body weight changes were significantly different between high (+10%), medium and low (-10%) feeding levels (P<0.05). A strong tendency to prolonged interval to first postpartum oestrus was observed on the low feeding level (P=0.09). No difference in feed conversion was observed between levels of feeding (Paper I). Feeding level and feeding strategy affected milk yield, body weight and fertility of crossbred lactating cows.

Experiments with different types of forages, forage/concentrate ratios and forage feeding principles were presented in Papers II and III. The daily milk yield increased following the increased concentrate ratios in the diets (40% vs. 50% vs. 60%, and 30% vs. 50% vs. 70%, respectively). The yield differences were significant between the highest and lowest treatments at constant forage/concentrate ratios, and between all treatments with ad libitum forage feeding. Increased concentrate ratios resulted in increased body weight gain and increased milk protein concentration, while milk fat decreased. No significant effect on postpartum oestrus was observed. The ad libitum forage feeding increased DM feed intake and milk yield compared to constant forage feeding.

Fresh elephant grass was partially replaced by 25%, 50% and 75% of urea treated rice straw (Paper IV). The daily ME intake was lower on 25% grass. There was a significant difference (P<0.05) in daily milk yield between the 100% and 75% vs. 25% grass. No differences in milk composition, body weight change and feed conversion were observed.

Keywords: crossbred F1 lactating cows, feeding level, forage/concentrate ratios, urea treated rice straw, milk yield, milk composition, body weight change, postpartum oestrus, feed conversion.

Author's address: Mai Van Sanh, National Institute of Animal Husbandry, Thuy Phuong, Tu Liem, Hanoi, Vietnam.

ISSN 1401-6249, ISBN 91-576-5819-6

Ngo Van Man, 2001

Better use of local forages for dairy cattle in Vietnam: Improving grasses, rice straw and protein rich forages. (December)

Ngo Van Man

Abstract saknas

Bui Xuan Men, 2001

Feeding and management systems for smallholder duck production in the Mekong Delta of Vietnam. (November)

Bui Xuan Men

Abstract

The studies presented in this thesis were carried out at the experimental farm of Cantho University and on smallholdings to investigate the efficiency of ducklings in controlling insect pests and weeds in rice cultivation, and to evaluate locally available feeds and feeding systems suitable for small farmers in the Mekong Delta of Vietnam.

Local and crossbred ducklings were used to control insect pests and weeds in the growing rice fields without using the insecticides and herbicides normally applied in rice cultivation. The ducklings integrated with rice cultivation replaced insecticides and herbicides and eliminated insect pests and weeds in the growing rice fields, resulting in increased total income of the farmers and substantial environmental benefits, especially with respect to pesticides. Cultivated fresh duckweed replaced commercial protein supplements in diets of local and Cherry Valley ducks and their crossbreds, and for both growing and breeding ducks. Fresh duckweed grown on ponds enriched with nutrients from organic matters could completely replace protein supplements in diets based on broken rice without reducing growth performance of local and crossbred ducks, and reproductive performance of local breeder ducks. Complete replacement of a protein supplement by fresh duckweed decreased feed costs provided that the duckweed was grown on farm and not purchased. Commercial diets with different levels of crude protein were offered pairwise to growing Cherry Valley broiler ducklings ad libitum. The ducklings preferred high protein over low protein feeds, resulting in excessive protein intakes, and higher protein conversion ratios, and it was concluded that choice feeding is not an economically viable system for growing meat ducks.

Key words: growing ducks, breeder ducks, pesticide, scavenging, duckweed, rice yields, dietary protein, choice feeding.

Author's address: Bui Xuan Men, Department of Animal Nutrition and Management, SLU, P.O. Box 7024, SE-750 07, Uppsala, Sweden.

Department of Animal Science, Faculty of Agriculture, Cantho University, Cantho City, Vietnam. E-mail: bxmen@ctu.edu.vn

ISSN 1401-6249 ISBN 91 –576-5809-9

Garaleviciene, D. 2001

Mycotoxins and moulded feed. Effects on laying hen and contamination of Lithuanian feeds. (October)

Garaleviciene, D.

Abstract

World-spread mycotoxins ochratoxin A (OA), zearalenone (ZEN) and trichothecenes deoxynivalenol (DON), nivalenol (NIV), T-2 toxin and HT-2 toxin are frequently found in cereals and feeds. In temperate areas, ochratoxin A is produced mainly by Penicillium fungi, which affect storaged grain, while trichothecenes and zearalenone are metabolites of Fusarium fungi that infect cereals in the field. Due to their high toxicity to humans and livestock, the studies on the effect of mycotoxins on animal health and production are important. Poultry farming is one of prevalent fields in Lithuanian agriculture. The effects of these mycotoxins and moulded feeds on poultry and preventive measures, also the toxin contamination of Lithuanian cereals were studied in this thesis.

In three of studies, the effects of diets, containing (I) pure NIV, (II) moulded grain and low amounts of OA, DON, NIV, ZEN and (III) mixed feed, containing small amounts of OA, DON and two mineral adsorbents were studied on poultry. Body weight, feed intake, productivity, egg quality and health status, based on the analyses of blood plasma parameters and post mortem examinations, were recorded. The in vivo distribution and excretion of pure NIV was also studied. The present results showed that pure NIV was without effect on poultry production and health and no its metabolites were found in eggs and tissues. Moulded grain with low toxin amounts containing diets had the adverse effects on feed intake, productivity and egg quality. Blood analyses distinguished that moulded feeds and mineral adsorbents added to the diets caused large variations in plasma enzymes and concentrations of other biochemical blood parameters indicating mainly liver and kidneys damages and non-inertness of adsorbents used. The pathological studies showed that pure NIV affects the reproduction organs in female birds while neither moulded feeds nor mineral adsorbents cause visible morphological effects.

In one of studies, Lithuanian grain and mixed feeds were analysed on their contamination with selected mycotoxins. Trichothecenes were detected in 8-68% of cereals and in 8-98% of mixed feed samples. ZEN and OA were found in 58-92% of mixed feeds for poultry and pigs, respectively. The concentrations found were lower those reported as Lithuanian advisory or tolerance limits.

Key words: alkaline phosphatase, cholesterol, de-epoxy-nivalenol, gamma glutamyl transferase, laying hen, Mycofix Plus, Mykoguard, plasma protein, uric acid, trichothecenes

ISSN 1401-6249, ISBN 91-576-5848-X.

Author's address: Dalia Garaleviciene, Department of Chemistry, Lithuanian Veterinary Academy, Tilzes 18, LT 3022 Kaunas, Lithuania.

Sallander, M. 2001

Diet and activity in Swedish dogs. (October)

Sallander, M.

Abstract

In this thesis the demographics, diet and activity in a defined population of 460 insured Swedish dogs between 1 and 3 years was presented. The data was collected by using a mail and telephone questionnaire. The repeatability (the questionnaire repeated to the same dog owners) and validity (questionnaire compared to 7-day weighed registration of dietary intake and recording of activity) of the questionnaire were examined, and shown to be good to excellent for most of the parameters measured. Also, the most commonly used commercial dog feeds were analysed, and the results were compared to the declared values and to the recommended nutrient profiles.

The insured dogs were shown to be representative for all Swedish dogs of the same age. A typical Swedish dog consumed 75% of the energy intake from commercial feeds, and a smaller part as table foods, but with large variations between individuals. Most of the dogs were fed total diets supplying adequate amounts of the nutrients compared to the recommended nutrient profiles. Total diets that did cause deviations from recommended levels were most commonly those consisting of only table foods (too low levels of vitamins and minerals) or commercial feeds supplied with extra vitamin and mineral supplements (too high levels of vitamins and minerals). The total energy intakes were comparable to previously published studies on maintenance energy requirements of adult dogs, but varied due to sex, breed and weight.

Three quarters of the dogs performed some type of activity for one hour or more per day, but although substantial variations were recorded, there was no significant difference in energy intake that could be related to the amount of activity recorded. There was a tendency (P=0.07) that the general temperament of the dog had an influence on the energy intake.

The analysed protein and fat content in commercial feeds was on average highly correlated with the declared values and with the recommended nutrient profiles. However, especially the calcium but also other minerals of commercial dog feeds often deviated from declared values, and did not always meet the AAFCO (2000) nutrient profiles. More expensive feeds had the same magnitude of deviation from declared energy and nutrient values as did feeds of a lower cost.

This validated questionnaire could be used to collect data on dietary intake and activity in future epidemiological studies in order to quantify the influence of these factors of the effects on health and disease in defined populations of dogs.

Key words: Dogs, canine, population, insured, demographics, telephone, questionnaire, survey, weighed record, Sweden, validity, repeatability, diet, feed, food, energy, protein, fat, carbohydrate, vitamin, mineral, activity, exercise, training, health, epidemiology.

Distribution: Swedish University of Agricultural Sciences, Department of Animal Nutrition and Management, SE-750 07 UPPSALA, Sweden

ISSN 1401-6249 ISBN 91-576-5840-4

Nguyen Nhut Xuan Dung. 2001.

Evaluation of green plants and by-products from the Mekong delta with emphasis on fibre utilisation by pigs. (September)

Nguyen Nhut Xuan Dung

Abstract

Four studies were conducted to evaluate the composition and nutritive values of green plants and by-products used as livestock feeds in the Mekong delta, Vietnam. In Paper I, 458 green plant samples were analysed in the laboratory. The mean crude protein (CP) and neutral detergent fibre (NDF) contents of green plants was 171 and 526 g kg-1 DM. Mean in vitro organic matter (OM) digestibility was 0.72 and was correlated with chemical analysis (R2=0.74).

The protein content of 116 green plants and 22 concentrates (Paper II) were fractionated into non-protein nitrogen (NPN), buffer soluble (B1), neutral detergent soluble (B2), acid detergent soluble (B3) and unavailable protein (C). NPN was high in immature, high-yielding plants and in tubers, B2 was dominant among the fractions, and B3 and C were high in fibrous and mature plants and high fibre by-products.

In Paper III, the NDF in vitro degradation kinetics was determined using caecum-colon and rectal inocula from pigs fed three different diets. The NDF degradation was similar between inocula but diet affected rate but not potential degradation.

In vivo and in vitro digestibility and digesta liquid and solids mean retention times (MRT) were measured in growing pigs fed high-fibre diets composed of green plants and by-products. In the 1st experiment, all diets, except the banana sheath diet, which was lower, had similar values for digestibility and MRT. Digesta MRT also was similar for the solids and liquid fractions in the pigs. In the 2nd experiment, digestibility of coarse rice bran and whole ground rice was significantly lower than other fibrous diets based on high of lignin and silica content. The correlation between NDF in vitro digestibility at 36 h and in vivo was high (R2=0.92).

Key words: green plants, by-products, protein fractions, in vitro, in vivo, digestibility, digesta retention, growing pigs.

Distribution: Swedish University of Agricultural Sciences, Department of Animal Nutrition and Management, P.O.Box 7024, SE-750 07, UPPSALA, Sweden

ISSN 1401-6249 ISBN 91 –576-5830-7

Palmgren Karlsson, C. 2001

Nutrient utilization in horses – Effect of oat replacement on ration digestibility and metabolic parameters (May)

Palmgren Karlsson, C.

Abstract

High performance increases the energy demands in the horse. The most common way to increase the energy density of the diet is to include higher levels of cereal grains. However, excessive amounts of starch can overload the capacity of starch digestion in the small intestine, and cause disturbances in the hindgut. Consequently, the use of alternative feedstuffs free from starch are of great interest. Fats and oils have a high energy content, and have been shown to be well utilized by the horse. Feedstuffs containing readily fermentable fibre, e.g. sugar beet pulp (SBP), could be another alternative to cereals.

The thesis summerizes and discusses results of three separate studies regarding nutrient digestibility and utilization of common horse rations based on hay and oats, fed to horses at maintenance energy level, and to high performing animals. Finally, methodological aspects for assessing nutrient digestibility were investigated.

When compounding rations for horses it is assumed that there are no associative effects of the individual feedstuffs included, and that increasing the inclusion level of a concentrate in a ration will increase the digestibility of organic matter (dOM) and energy(dE) linearily. The results presented in this thesis show that at high dietary proportions of oats (60% of dry matter intake) negative associative effects on the nutrient digestibility may occur as a result of impaired digestibility of fibrous components. Partial replacement of oats with SBP and/or maize oil had only limited effects on total tract nutrient digestibility.

Further, there is a negative relationship between the dietary content of fibrous components and dOM and dE, respectively, and it was concluded that the dietary content of ADF and crude fibre will give the best estimate of dOM and dE.

Partial replacement of oats with SBP results in lower levels of plasma and muscle lactate and higher levels of muscle glycogen following exercise, indicating an influence of dietary carbohydrate composition on nutrient utilization at the organ level. The inclusion of fermentable fibre in the diet for exercising horses offers an interesting alternative to current strategies in diet formulation.

Key words:, hay, oats, sugar beet pulp, maize oil, fibre, apparent digestibility, associative effects, nutrient utilization, glucose, insulin, lactate, muscle glycogen, muscle lactate, quantitative collection, marker ratio technique, acid insoluble ash, chromic oxide, lignin.

Author's address: Carina Palmgren Karlsson, Department of Animal Nutrition and Management, SLU, Box 7024, SE-750 07 UPPSALA, Sweden.

ISSN 1401-6249, ISBN 91-576-5800-5.

Madej, M, 2001

The Porcine Gastrointestinal Epithelium. Metabolism of Glutamine for Energy Production. (April)

Madej, M

Abstract

The primary aim with this thesis was to study developmental effects on the activity of selected key enzymes involved in the metabolism of glutamine in the porcine gastrointestinal epithelium. Further, methods for isolation and culturing of porcine gastrointestinal epithelial cells were evaluated.

In general, the activities of individual enzymes were higher in the epithelium of the small intestine than in the stomach and colon, independent of age. The contribution of glutamine for energy production decreased with age and the enzymatic capacity of the tricarboxylic acid (TCA) cycle to utilise acetyl-Coenzyme A (acetyl-CoA) increased with age, parallel with changes in diet composition. However, the entry of acetyl-CoA into the TCA-cycle was limited by the citrate synthase activity in the small intestinal epithelium of suckling piglets and during suckling-weaning transition. The gastrointestinal epithelium shows a high capacity to metabolise a-ketoglutarate, independent of age. The glutamate dehydrogenase activity decreased in the small intestinal epithelium during the 1st week after weaning. The capacity of the TCA-cycle for transformation of a-ketoglutarate exceeded the capacity for its formation from substrates that enter the TCA-cycle as acetyl-CoA during suckling-weaning transition. It was suggested that a-ketoglutarate in the gastrointestinal epithelium of new-born and suckling piglets, might be provided from glutamate by an alternative pathway, not involving alanine aminotransferase. Further, the gradually increasing activity of aspartate aminotransferase, indicated that the capacity to metabolise amino acids and to provide the TCA-cycle with oxaloacetate could be maintained in the epithelium of the small intestine during suckling-weaning transition.

The presence of nivalenol in the diet reduced the activity of a-ketoglutarate dehydrogenase in the epithelium of the small intestine and colon of growing pigs, and tended to increase the activity of alanine aminotransferase in the small intestinal epithelium.

An effective disaggregation of the gastrointestinal tissue was obtained with incubation at 37oC in a medium saturated with 5% CO2 and 95% O2, containing DTT (dithiothreitol) in the initial step, and EDTA (ethylenediaminetetraacetic acid) and/or hyaluronidase in following steps. An increase of cell numbers isolated by the enzymatic method occurred within two days of culturing. Survival of cultured porcine intestinal epithelial cells was possible for as long as 20 days.

Key words: gastrointestinal epithelium, piglets, suckling-weaning transition, glutamine oxidation, energy metabolism, enzymes, nivalenol, cell isolation methods, cell culture.

Author's address: Malgorzata Madej, Department of Animal Nutrition and Management, SLU, Box 7024, SE-750 07 UPPSALA, Sweden.

ISSN 1401-6249, ISBN 91-576-5783-1.

Lindström, T. 2000

Feeding behaviour in dairy cows. Motivational aspects. (December)

Lindström, T.

Abstract

In this thesis I summarise and discuss the results of studies regarding motivational aspects on feeding behaviour in dairy cows. Questions addressed concern how feeding duration and rumen fill in cattle influence some behavioural variables reflecting frustrated feeding motivation, such as stereotypies and behaviours related to feed-searching, and also how rumen fill and feeding duration relate to oxytocin and cortisol. We have also investigated if operant conditioning is a useful method to measure and quantify the motivational strength to obtain roughages with different characteristics and sensory qualities. The aim was to test the hypothesis that oral manipulation of feed is a behavioural need in cattle, irrespective of rumen load.

Low rumen content and long eating time had the effect that the cows spent a rather short time with behaviours related to feed-searching and showed low levels of stereotypies. The cows with long eating time had a larger oxytocin release during the afternoons compared with the cows with short eating time. The cows with high rumen content and short eating time spent relatively more time with behaviours related to feed-searching and with stereotypies. The cortisol concentration in the morning sampling period was higher in the treatment with short eating time compared with the cows with long eating time.

The studies with operant conditioning showed large individual differences between cows in their motivation to work for feed in general. The results also showed that cows have individual preference for one specific side.

It can be concluded that oral manipulation of feed is a behavioural need in cattle irrespective of rumen load. A short duration of feeding behaviours combined with a low rumen load seriously impairs the welfare of cattle. The results imply that there are physiological mechanisms, possibly in the form of oxytocin, involved in the motivation of feeding. I also conclude that operant conditioning could be a fruitful method to measure and quantify feed preference of dairy cows. However, the results only reflect the preference of the individual animal, and a complete mapping according to side preference must be done of each individual included in the experiment.

The practical implication of these studies is to provide all cows with sufficiently long eating time, preferably by constant access to roughage.

Keywords: Feeding, behaviour, stereotypies, motivation, dairy cows, oxytocin, cortisol, operant conditioning.

Distribution: Swedish University of Agricultural Sciences, Department of Animal Nutrition and Management, P.O Box 7024, SE-750 07 Uppsala, Sweden

ISSN 1401-6249, ISBN 91-576-5761-0.

Le Duc Ngoan, 2000

Evaluation of shrimp by-products for pigs in Central Vietnam. (December)

Le Duc Ngoan

Abstract

The aim of this thesis was to evaluate by-product yield of different shrimp species, and to determine chemical and amino acid composition, ensiling techniques and nutritive value, including ileal and total tract digestibility of shrimp by-product, and effects of inclusion of ensiled shrimp by-product in diets on the performance of growing crossbred (Large White x Mong Cai) pigs.

The results show that edible shrimp flesh and shrimp by-product yield of the three major shrimp species investigated averaged 56.7 and 43.3%, respectively, of total wet weight. Significant differences in by-product yield were found between shrimp species, and in dry matter, crude protein and ash content between shrimp flesh and shrimp by-product. Shrimp by-product was characterised not only by high crude protein, chitin and calcium content, but also by low methionine concentration in crude protein.

Shrimp by-product can be preserved for at least 2 months by ensiling with molasses at a ratio of 3:1 or cassava root meal at a ratio of 1:1.

The inclusion of shrimp by-products, particularly the ensiled material, in growing pig diets decreased total tract digestibility of organic matter and crude protein, and lowered N-retention and daily feed intake. However, replacing 50% of the crude protein of fishmeal in diets by ensiled shrimp by-product did not affect pig performance. Completely replacing the crude protein of fishmeal did reduce performance, although it did not alter carcass characteristics of fattening pigs.

It can be concluded that from nutritional and economic aspects shrimp by-product could be included at levels of up to 7% (DM basis) in cassava root meal and rice bran-based diets for growing crossbred (Large White x Mong Cai) pigs under Vietnamese conditions.

Key words: Pigs, shrimp by-product, ileal digestibility, amino acid, molasses, cassava root meal, silage.

Distribution: Swedish University of Agricultural Sciences, Department of Animal Nutrition and Management, P.O Box 7024, SE-750 07 Uppsala, Sweden

Author's address: Le Duc Ngoan, University of Agriculture and Forestry, 24, Phung Hung, Hue City, Vietnam

ISSN 1401-6249, ISBN 91-576-5757-2

Bui Huy Nhu Phuc, 2000

Tropical forages for growing pigs. Digestion and nutritive value. (December)

Bui Huy Nhu Phuc

Abstract

The tropical zones contain the biggest genetic diversity of plant species, and particularly of vascular plants. Tropical forages are of interest in providing protein rich green biomass that is not directly used in human nutrition. Nine potentially useful biomass products were investigated: trichantera leaves (Tric), leucaena leaves (LL), indicago leaves (Ind), groundnut foliage (GF), mung bean vines (Mb), cassava leaves (CL), and sweet potato vines (SPV). Two aquatic plants, water spinach (WS) and duckweed (DW), were also studied in this context as alternative protein sources for monogastrics. The general aims of the studies were to estimate the nutritional value of these nine biomass products and the effects of preservation method in balance experiments with rats and pigs with different levels of inclusion. The effect of drying and ensiling technique of CL on HCN levels was also studied.

The results of chemical analyses indicated that there were marked differences in chemical

composition among the plant species. The content of organic matter (OM) varied from 73.6 to 92.8 % of dry matter (DM). The crude protein (CP) content of the biomass products was rather high, varying between 20.9 % and 33.2 %, and the content of NDF varied between 18.5 % and 32.2 % of DM. The total content of essential amino acids (EAA) in g per 16 g N was comparable with that of alfalfa meal. Between plant species differences in digestibility of OM and CP were observed. Also, increasing level of inclusion lowered dOM and dCP at the ileal and total tract level in both rats and pigs. Significant differences were found in N-retention and biological value between diets with the different biomass products. The main factors affecting the nutritive value of the diets tested were their NDF contents and the dCP and AA profile. Also antinutritive component(s) may have influenced the process of digestion and metabolism of some of the biomass products.

Drying CL at 105 oC resulted in a reduction of the lysine content, which indicated the occurrence of Maillard reactions decreasing dCP as well as N retention. Ensiling CL and SPV slightly decreased the CP content as well as the sum of EAA. Sun-drying and ensiling with cane molasses as additive successfully preserved nutrients and could be a means of preserving fresh green feed under tropical conditions. The effects of sun-drying and oven-drying in reducing the HCN content in CL were more potent than ensiling. The most favourable overall results in terms of nutritive value were obtained for DW, WS, Mb, GF, SPV and CL.

Key Words: Tropical Biomass, Biological Value, Rats, Drying, Ensiling, Leaves, Nutrient Digestibility, Pigs,

Distribution: Swedish University of Agricultural Sciences, Department of Animal Nutrition and Management, P.O Box 7024, SE-750 07 Uppsala, Sweden

Author's address: Bui Huy Nhu Phuc, Department of Animal Nutrition, University of Agriculture and Forestry, Thu duc, Ho Chi Minh City, Vietnam

ISSN 1401-6249, ISBN 91-576-5755-6

Nguyen Van Thu, 2000

Urea-molasses based supplements for multipurpose buffaloes. (October)

Nguyen Van Thu

Abstract

This thesis investigates the effect of work and/or urea-molasses based supplementation on performance (Paper I and II), rumen environment, feed digestibility and utilization (Paper III and IV) in buffaloes. In Paper V the use of fecal inocula for in vitro digestibility determination is reported. Pregnant buffaloes fed elephant grass and sugar cane tops ad libitum, supplemented with rice bran and urea-molasses blocks could effectively operate a sugar cane crusher. In the lactating buffaloes a temporary reduction in milk yield and live weight was noted during the 3-week working period and suppressed ovarian activities (Paper I). Pairs of lactating Murrah buffaloes pulling sledges (Paper II) fed grass and rice straw ad libitum or grass only, supplemented with rice bran and urea-molasses cakes exerted a 3,400-3,700 kJ work force. There was a reduction of 0.5kg milk/d during the 3-month working period, but supplementation prevented live weight losses. Urea-molasses cake (UMC) supplementation (Paper III) increased ruminal NH3-N, microbial populations and intake in buffaloes fed rice straw ab libitum or rice straw plus grass. In Paper IV, UMC including soybeans significantly increased rumen fermentation, total tract digestibility, feed intake and live weight gain in buffaloes fed rice straw. Supplementation did not affect in sacco or in vitro digestibility. In Paper V no in vitro digestibility differences were found among cattle and buffaloes using rumen or fecal inocula. Feces could potentially replace rumen fluid as inocula for in vitro digestibility determinations.

It is concluded that: i) buffalo cows can be used for work and, milk but nutrient supplementation is necessary, ii) urea-molasses cake supplementation improves rumen function, feed intake and live weight of buffaloes and iii) feces can potentially be used as inocula for in vitro digestibility determination. iv) UMC for buffaloes requires further evaluation in order to improve the technique and farmer adoption.

Key words: buffaloes, urea-molasses supplements, digestibility, rice straw, fecal inocula.

Distribution: Swedish University of Agricultural Sciences, Department of Animal Nutrition and Management, P.O Box 7024, SE-750 07 Uppsala, Sweden

Author's address: Nguyen Van Thu, Dept. of Animal Husbandry, Faculty of Agriculture, Can Tho University, Can Tho City, Vietnam.

ISSN 1401-6249, ISBN 91-576-5796-3

Andresen, N. 2000

Urea-molasses based supplements for multipurpose buffaloes - Resource Utilisation, Interaction, Performance and Behaviour of Pigs in Cropping Systems . (October)

Andresen, N.

Abstract

This thesis works with the hypothesis that the natural behaviour of pigs can be incorporated in the design of agroecosystems to benefit both crop and animal performance. The work is based on knowledge of ecosystem principles supported by experiments dealing with the behaviour and performance of outdoor pigs on clover/grassland as well as tillage effects due to rooting by pigs on winter wheat performance the following year.

An analysis of resource flows in pig production showed that environmental loading in an ecological pig production system (EPS) was 64% less than in a conventional housing system (CPS). This was mainly due to a larger area base, less dependency on purchased resources and a tighter feed-back relationship between crop and pig production. Labour requirements in EPS were larger than in CPS. On-farm production of feed in EPS reduced purchased inputs for feeds by 48% compared with CPS. Both systems were dependent on purchased inputs from a higher system level, where non-renewable resources were the primary driving sources.

Levels of pig tillage due to rooting, and yields of winter wheat grain in the following year were significantly correlated (r = 0.54). In dry conditions an increased stocking rate was necessary to achieve a pig tillage effect, which gave yields comparable to mechanical tillage. Larger grain yields were achieved on the areas treated by pigs compared with mechanical tillage, when soil moisture content was high. Mean daily weight gain varied between 626 and 811g and the supplemented concentrate conversion ratio (CCR) of metabolizable energy varied between 38 and 48 MJ kg-1 live weight gain in the experiments. CCR was improved with increasing live weight indicating a large maintenance requirement for energy, especially in young pigs, probably due to high levels of activity. Rooting activity increased when soil moisture content increased or supplemental feeding was restricted. Increasing air temperature and reduced access to herbage decreased grazing activity. Daily allocation of new land stimulated foraging activity and deposition of urine and faeces in the newly allotted land.

Keywords: ecological agriculture, outdoor pigs, multifunctional animal husbandry, behaviour, resource use, animal capabilities, integration, soil tillage work, interaction

Distribution: Swedish University of Agricultural Sciences (SLU) Uppsala 2000

Department of Animal Nutrition & Management P.O. Box 7024, 750 07 Uppsala, Sweden ISSN 1401-6249 ISBN 91-576-5764-5

Olofsson, J. 2000

Feed availability and its effects on intake, production and behaviour in dairy cows. (May)

Olofsson, J.

Abstract

The aim of the present investigations was to study the performance of dairy cows at different availability of feed. Three studies mainly concerned feed competition in loose housing systems, while two other studies analysed physiological response to feeding during milking, and performance in an automatic milking system (AMS) with forced cow traffic, respectively. All studies were conducted at the University Cattle Research Centre (Kungsängen) in Uppsala, Sweden. The studies were performed using dairy cows of the Swedish Red and White dairy breed.

Cows in loose housing responded to ad libitum feeding by consuming approximately 20 - 25% more feed than their calculated need; more than 70% overconsumption was seen for individual cows. As a comparison, a change to twice daily feeding of restricted rations, limited to approximately 10% above the requirement of the group, affected some cows by reducing their feed intake below their calculated need, and altered the feeding rhythm. Competition for feeding space could only be recommended if allowing ad libitum rations, since the combination of restricted feeding space and restricted rations resulted in much higher aggression levels during feeding and difficulty for some cows to consume enough feed. Production tended to decline when changing from ad libitum rations to restricted feeding. High yielding cows tended to decrease their production when combining restricted rations and limited feeding space.

Supplementary feeding of concentrates in connection with the onset of milking was advantageous. Feeding concentrates during milking was seen to induce a higher oxytocin release into the blood and to improve milking performance by way of shorter milking times, higher milk flows and greater milk removal from the udder.

Cows in AMS preferred a diurnal rhythm with less attendance to milking and feeding during late nights and early mornings. They also consumed less feed per meal during those hours and showed a higher feed consumption when visiting the feeding area after milking compared to when they had not been milked. Feed consumption was seen to increase with increased intervals between meals. Cows low in social rank did not manage to visit the milking unit and the feeding area as often as socially dominant cows did.

Key words: dairy cattle, animal behaviour, time budget, feed intake, ad libitum feeding, restricted feeding, TMR, total mixed diets, competition, social dominance, milk production, AMS, oxytocin.

Department of Animal Nutrition and Management, Kungsängen Research Centre, SE-753 23 Uppsala.

ISSN 1401-6249 ISBN 91-576-5752-1

Johansson, B. 2000

Effect of milking and feeding routines on milk production, hormone release and behaviour in dairy cattle (February)

Johansson, B.

Abstract

In the present work we studied the effects of the milking routines; manual prestimulation of the udder, feeding in relation to milking, and suckling by the calf on milk production, oxytocin, prolactin, cortisol, some GI hormones and behaviour. A possible role for oxytocin in co-ordination of physiological and behavioural adaptations to lactation in dairy cows was also investigated.

When the routines for manual prestimulation and feeding during milking were compared the only significant difference was a more efficient udder evacuation caused by feeding. When used together positive effects were found on machine-on time and average milk flow.

When cows were fed during milking an higher milk yield and a changed milk composition were seen. The milking-related hormones were also influenced. The release of oxytocin was greater and the milking-induced release of cortisol was reduced compared with milking alone. The behaviour was influenced in such a way that the cows were lying down more and ruminated more while lying down, when measured from onset of milking and compared with milking only.

Positive relationships were found between milking-related oxytocin and prolactin, cortisol, milk yield and the lying down behaviour. The correlations with oxytocin indicate that this peptide may play an integrated role in adapting dairy cows to lactation, both from a physiological and a behavioural point of view.

Suckling induced a higher release of oxytocin than machine milking in the cow or bucket drinking in the calf. In the calf, a positive correlation between oxytocin and insulin was found during suckling suggesting that the suckling stimulus may have activated a more anabolic type of metabolism.

In conclusion, enhanced sensory stimulation by feeding during milking and by suckling in cows and calves seems to be linked to an enhanced oxytocin secretion. Furthermore, the data indicate that a routine of prestimulation coupled with feeding during milking could optimise milk ejection. Further studies are needed to investigate physiological effecs of suckling on the cow and calf.

Key words: Behaviour, calves, CCK, cortisol, dairy cows, feeding, gastrin, insulin, milking, oxytocin, prolactin, somatostatin, suckling

Address:Department of Animal Nutrition and Management, P.O. Box 7024, 750 07 Uppsala

ISSN 1401-6249 ISBN 91-576-5733-5


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