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The utilization of Pennisetum purpureum (Napier grass var Bana) based diets and the lactation performance of dairy cows in coastal lowland Kenya was studied in a series of five experiments. In experiments 1 and 2, the effects of 300g/day additional crude protein from locally available fishmeal, copra cake and Leucaena were compared using Jersey cows fed ad libitum Napier grass. Experiment 1 carried out in early lactation, showed that supplements (fishmeal or copra cake) could increase dry matter DM intake, reduce live-weight loss and increase (P< 0.05) milk output (7.8 v 6.4kg/day) with no differences between the supplements. Experiment 2 was carried out in mid lactation. Cows fed supplements (a mixture of copra cake/maize bran or Leucaena) consumed more (P< 0.01) DM with no effect on Napier grass intake and produced more (P< 0.05) milk no difference between supplements. No significant changes in live weight were observed. Ayrshire/Brown Swiss x Sahiwal cattle were used in experiments 3 to 5. In experiment 3, the effects of Napier grassharvesting height (1.0 v 1.5m) and level of Leucaena (0,4 and 8kgFW) were evaluated in early lactation. Feeding Napier grass harvested at 1.0m compared with 1.5m increased (P&60 0.01) Napier grass intake (9.3 v 6.8kg/day), reduced live-weight losses (0.16 v 0.49kg/day) and increased milk yield (8.6 v 6.9kg/day). Feeding Leucaena (0, 4 and 8kgFW; DM280g/kg) significantly (P< 0.01) increased total DM intake (7.8, 9.3 and 10.4kg/day), reduced live-weight loss (0.53, 0.23 and 0.17kg/day) and increased milk yield (7.3, 7.7 and 8.3kg/day).

There is evidence from a number of species that body condition or fatness plays a role in the regulation of energy balance, through a direct effect on voluntary food intake (VFI). However, since differences in body condition are frequently confounded with differences in previous nutrition, this study investigated the role of both factors in the control of VFI in sheep. In ewes grazing autumn pastures, there was a negative effect of body condition on VFI, but no independent effect of the previous level of nutrition. However, there was an interaction between the effects of body condition and herbage availability on intake, since VFIs of fat ewes differed with sward height while VFIs of thin ewes did not. The effect of early nutrition on VFI in growing lambs was studied in an experiment where ewes were given either a restricted or adequate level of nutrition in late pregnancy and early lactation. Mean live weight and gut development at weaning were reduced in lambs whose nutrition was restricted during both pregnancy and lactation, but subsequent VFI was not affected. Feeding behaviour was investigated in fat and thin sheep eating a pelleted diet. Thin ewes had higher intakes and spent more time feeding that fat ewes, but the number of meals and rate of ingestion during meals was the same. Both fat and thin ewes increased meal frequency and ingestion rate when food access time was reduced. Differences in VFI were found to persist longer than differences in body condition. Basal plasma insulin concentrations and those measured following an exogenous insulin challenge were both higher in sheep that had remained fat, than in sheep that had previously been thin. This is consistent with the hypothesis that insulin may provide a long-term negative feedback signal to the brain in fat animals, resulting in lower VFIs.

The aims of the present study were to evaluate the suitability of Colombian rice polishings (RP) as a feed supplement for ruminants and to study its effect on rumen fermentation. The quality of RP appeared to be uniform and independent of the period of the year when the RP were collected. The low content of particles greater than 2 mm2 separated on sieving, combined with the low ash content suggested that the RP used in the current studies contained little broken rice or rice hulls. The proximate analysis of RP suggested a by-product which represented a good source of carbohydrates (starch), protein and phosphorus, but contained a high fat concentration (254, 143, 12.7 and 180 g/kg DM respectively). Of the total fatty acids in the oil 0.77 were unsaturated. Full-fat RP were fermented in the in vitro Menke system less efficiently than other substrates containing medium quality hay, starch or cellulose, but were apparently more degradable when measured in sacco. However, for each diet at 4, 8, 24, and 48h incubation there was a significant correlation (r2=0.97) between the amount of DM degraded in sacco and the gas production measured in vitro (P<0.01)'. The evaluation of RP in the in vitro Rusitec system indicated that any adverse effects of high lipid concentration of RP, such as the potential for an inhibition in bacterial growth, appeared to be outweighed by a nonsignificant stimulation in microbial activity resulting from the inclusion of this rapidly degradable substrate in the diet. An in vivo study with adult sheep suggested that at the level tested RP, as an alternative to urea molasses did not increase the efficiency of rumen fermentation and were not as effective a supplement with urea as molasses for a low quality forage diet. Measurements of in vitro fermentation of sieved fractions suggested that the rate of degradation in the rumen fluid decreased as particle size increased in excess of 2 mm2, in vitro batch culture results suggested that RP crude protein is highly and rapidly degraded in the rumen. In the current study RP were a rapidly degradable substrate in the rumen, represented a source of RDP and the high ammonia concentration recorded may indicate an intraruminal n recycling possibly due to an enhanced Protozoal population.

In experiment 1, groups of wild (W) and farmed (F) weaned calves were maintained at either high (H) or low housing (L) density. W calves had lower antibody titres and lower lymphocyte responses to antigen than F calves (P<0.05). At the start of the study, W and H calves exhibited a greater plasma cortisol response to ACTH than F and L calves, respectively (P<0.05), but thereafter there were no significant differences. Wild calves were less active than F calves (P<0.01) and WH calves were the most aggressive (P<0.1). In experiment 2, individual wild yearlings were grouped with farmed yearlings. Groups were remixed every week, for 4 weeks. The incidence of agnostic behaviour was greater in mixed deer than in the control deer, maintained in the same groups throughout the study (P<0.001). At the end of the study, mixed yearlings had greater plasma cortisol responses to ACTH than control deer (P<0.05). Lymphocyte response to antigen was lower in mixed than controls (P<0.05), but there were no differences in antibody response. In experiment 3, groups of weaned calves were subjected to either aversive (AV) or non-aversive (NAV) handling treatments. Lymphocyte responses to antigen tended to be lower in AV than NAV calves (P<0.05). After three weeks, AV had greater plasma cortisol responses to ACTH than NAV calves (P<0.05), but treatment had no measurable effect on fearfulness. In experiment 4, weaned calves were housed either individually (ISO) or in groups (GP). ISO were less active (P<0.001) than GP calves. Antibody and lymphocyte responses to antigen were greater (P<0.05) in ISO than GP calves. Overall, stressors associated with group-housing consistently lowered lymphocyte response to antigen, but antibody responses were less consistent. Differences in immune responses corresponded to changes in behaviour, but not productivity or cortisol response. It is concluded that social stress had a greater impact on immune function than social isolation and aversive handling.

CHAPTER 2 Five experiments were conducted to investigate the dietary factors within the rumen environment which could contribute to the rate of degradation of straw. Three sources of digestible cellulose and/or hemicellulose (unmolassed sugar beet pulp, citrus pulp and dried grass) and two sources of natural proteins (fish meal and soya bean meal) were investigated for their ability to increase degradation of straw In. sacco in sheep, as supplements to untreated straw. The untreated straw used in these experiments was adequately supplemented with rumen degradable nitrogen, sulphur, vitamins and minerals. Unmolassed sugar beet pulp and dried grass when given at a level of 150 g.kg DM-1, increased both the rate and extent of DM degradation of straw In sacco. Citrus pulp and soya bean meal had no effect on straw degradation while fish meal increased the extent of straw DM degradation. The rumen NH3 levels and pH in both the control and supplemented animals were above the range that would be expected to cause an inhibition in fibre digestion. It was concluded that digestible cellulose/hemicellulose and fish meal improved the conditions in the rumen for fibre degradation in animals given straw diets. CHAPTER 3 The supplementary effects of unmolassed sugar beet pulp and fish meal on intake, digestibility and growth performances of sheep, given either untreated or ammonia treated straw, were investigated using twenty four sheep. The experimental design was a 2 x 2 x 2 factorial layout. Unmolassed sugar beet pulp and fish meal increased untreated straw digestibility by 10% and intake by 16-22%. The supplements had no effect on the digestibility or intake of basal ammonia treated straw. Ammonia treatment alone however increased the intake and digestibility of untreated straw by 76% and 16%, respectively. The growth achieved in this experiment was highly correlated to the intake of total digestible DM. CHAPTER 4 Two experiments were conducted to study the supplementary effects of unmolassed sugar beet pulp and fish meal on intake, digestibility and growth performance of cattle given either untreated or ammonia treated straw. Twenty four Hereford x Friesian steers and thirty two Friesian cross steers and bulls were used for the two experiments respectively. The first experiment was conducted for ten weeks, while the second experiment was continued for twenty weeks. Both the experiments were of 2 x 2 x 2 factorial design. Unmolassed sugar beet pulp and fish meal when given in a combination increased the intake and digestibility of untreated straw. Similar to the results of the sheep experiment (Chapter 3) these supplements did not change the intake or digestibility of ammonia treated straw. Ammonia treatment however increased the intake by 22 and 2 and digestibility by 26 and 14% in these two experiments. The growth observed in the first experiment was higher than expected, but in both experiments growth was related to total digestible DM intake. CHAPTER 5. Methods to predict the rate and extent of roughage degradation in different rumen environments were investigated. The activities of two particle-bound microbial enzymes were measured, glutmate dehydrogenase (GDH) and carboxymethyl cellulase (CMCase). A method was developed and standardized to measure particle-bound microbial enzymes after incubating straw contained in nylon bags in the rumens of sheep given different diets. Using this method particle-bound enzyme activities were correlated with dry matter degradation in the rumen. Particle-bound NAD-linked GDH activity showed no relationship to dry matter degradation while particle-bound CMCase activity showed a very high correlation with the rate and extent of straw degradation. It was concluded that measuring particle-bound CMCase activity at 8 or 16 hr incubation periods could be useful in predicting the rate and extent of DM degradation of straw. CHAPTER 6 The results were discussed in relation to the view that the 'rate limiting: steps' that control digestion and intake of low quality roughages such as rate of fibre degradation, rate of particle size reduction, and the rate of passage of undigested material from the rumen depend upon: (a) proportion of the fibre-degrading organisms in the total microbial population (b) factors related to the roughage such as 'fragility' (c) animal species (i.e. sheep or cattle). Practical implications of the findings for animal production were evaluated on a nutritional and economical basis and it was concluded that the judicious supplementation of untreated straw with a source of digestible cellulosic/hemicellulosic material and a slowly degrading natural protein could replace ammonia treatment of straw, but has to be reassessed in different parts of the world depending on the availability and cost of the supplements.

The main objectives of the work described in this thesis were to determine the technical feasibility of utilising date palm leaves as a potential source of roughage, and to study the effects of providing brackish water as a source of drinking water for dairy cows. Additionally, to investigate the effect of feeding a high concentrate diet on the performance of Friesian cows. Four experiments were performed during the course of three years (November 1988 - June 1991). Three experiments were carried out in Kuwait and one in the North of Scotland. Experiment 1 was designed to compare the effects of feeding locally produced date palm leaves (DPL) with imported barley straw (S) as roughages to milking cows given a high concentrate diet. Fifty-six cows were used from the fifth week of lactation for 12 weeks. Experiment 2 studied the performance of thirty eight non-lactating pregnant cows for about 15 weeks, with the same objective as experiment 1. Each of these experiments included a small trial for more detailed studies. In experiment 3 eight milking cows in the sixth week of lactation were studied for over six months to compare the effects of drinking brackish water (BW) with fresh water (FW) on the performance of the cows fed on a high concentrate diet in addition to DPL and freshly cut alfalfa. Experiment 4 was conducted in the North of Scotland to investigate the effects of feeding a high concentrate diet, similar to that of Kuwait, on the productivity and the ruminal fermentation of high yielding cows. The general conclusions drawn from these four experiments are: 1. Despite the low qulaity of DPL, it might be a suitable alternative to straw as a source of roughage for dairy cows in Kuwait. 2. Brackish water is a palatable and harmless source of drinking water, and its mineral content may be beneficial in contributing to the dairy cows dietary requirements. 3. Feeding a high level of concentrate in diets based on grass silage increases milk yield and favours body gain at the expense of milk fat content. 4. There is a need for better utilization and processing of local agricultural by-products in Kuwait for the feeding of ruminants. 5. Further research is required to investigate the performance of dairy cows under different environments, especially hot-arid conditions.

Prior to giving birth, sows are normally confined in crates. One of the current aims in pig production is to develop an alternative farrowing system in which the sows are unconfined and grouped together. The aim of the new system is to improve the welfare of the sow and litter whilst maintaining high levels of productivity. Four studies were conducted to document the nest building and social behaviour of sows so that the system can be designed to suit their needs. The fifth study compared the productivity of unconfined individual and grouped sows with confined sows. Study 1. Six sows were housed in a pen which contained a sand floor and straw dispenser. Nine and a half hours before farrowing the sows displayed rooting, pawing and straw carrying and removed 23 kg straw to build a nest with hollow, straw lining and nest rim. Six sows were presented with similar nests. Nest building behaviour was affected by feeding behaviour. Study 2. Sixteen sows were presented with a hollow (H), a mattress (M), a nest box (B) which represented the 3 nest features and a control (C). Farrowing site preference was (H) 6, (M) 6, (B) 4 and (C) 0. In trial 2, (C) was replaced by a straw area (S), all 16 sows farrowed in (S) when it contained 4.5-18 kg straw. At 2.25 kg preference was (H) 1, (M) 3, (B) 1, (S) 3. Nest building behaviour was not affected by the amount of straw in (S).Study 3. Four previously confined and 3 unconfined sows were housed in a pen which included a straw (S), a central food (F) and a control (C) area. Entry into (S) and (C) was contingent on 10 panel presses. Food was delivered into (F) every 2 hours. The sows pressed the panel for (S) more than (C). Nest builidng behaviour was affected by feeding behaviour. Confined sows tended to show more behaviour associated with the straw. In trial 2, 5 sows were housed in pen which included a straw (S), a central (C) and a food (F) area. Cost of entry into (S) and (F) was gradually increased. Food was delivered into (F) every 45 mins. The fall in work rates for straw and food were similar as the cost was increased. The work rate for straw was increased 24 hours before farrowing. Study 4. Twenty-two sows were paired with an unfamiliar conspecific in pens which contained 2 strawed lying areas. As farrowing approached, the sows spent less time lying together and the aggressive behaviour of 12 dominant prepartal sows increased significantly. The level of aggression was significantly reduced in 11 dominant prepartal sows paired with unfamiliar conspecifics in modified pens and between 9 pairs of pre-partal sows which were familiar with each other. Sows were observed to lie together at farrowing and to farrow in more than one lying area. Study 5. Appetite and piglet mortality was compared for 43 sows in straw pens, 51 sows housed with pen-mates in straw pens and 50 sows in farrowing crates. Appetite was not reduced during the periparturient period or affected by pen type. There was no difference in the number of piglets which died during the first 24 hours after farrowing in the 3 pen types. Sows in farrowing crates tended to have more stillborn piglets.