School of Agriculture, Food and Ecosystem Sciences - Theses
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ItemThe ability of sheep and goats to utilize crop by-products( 1977)Two digestibility trials and one feeding experiment were implemented. In the first digestibility trial sheep were fed rations of hay to which was added (w/w} 10%, 20% and 30% of rice bran, soybean meal and cassava respectively. The results showed that changes in digestibility were not directly proportional to the amount of the ingredient added, thus the individual analysis or digestibility of a single food does not necessarily indicate its feeding value in mixed diet. In the second trial the digestive efficiency of sheep and goats was compared when fed low, medium and high quality diets as represented by oat straw, meadow hay and sheep fattening pellets. For all practical purposes the sheep and goats were similar in their ability to digest all diets but there was some evidence to show that the goats made better use of crude protein in the oat straw and crude fibre in the pelleted diet. In the feeding experiment the same by-products that were used in the first digestibility trial were variously combined to investigate the best mixture for fattening sheep. The best liveweight gains were obtained from diets D2 and D3. D2 contained 33% hay, 30% rice bran, 25% cassava and 12% soybean meal.' D3 comprised 40% hay, 15% rice bran, 30% cassava and 15% soybean meal.
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ItemEffects of growth patterns on body composition and compensatory growth in sheep( 1977)The literature related to compensatory growth in ruminants, with particular reference to sheep, has been reviewed. An experiment was conducted which examined the effects of planned BW losses on growth rate, body composition, wool growth and nitrogen and energy utilisation of sheep when ad libitum feeding was resumed. Sheep were fed a pelleted ration throughout the experiment, and BW loss induced by reducing feed intake. Following developmental growth from 30 to 37.8 kg, Groups B and C lost 21% BW at 122 and 63 gd-1, respectively to reach 30.2 kg BW. Following developmental growth from 30 to 46.7 kg (Groups D and E), Group D lost 34% BW at 125 gd-1 to reach 30.8.kg BW, while Group E lost 23% BW at 157 gd-1 to reach 35.0 kg. Group A was a control group fed ad libitum throughout the experiment. When ad libitum feeding was resumed compensatory growth occurred in treatment groups for up to 10 kg recovery of BW. Group D showed the most persistent increases in growth rate compared with that of control sheep, however, above 50 kg BW there were no significant differences between groups in growth rate. Weight loss did not produce a reversal of the compositional changes which occurred with increasing BW during developmental growth, in the whole body, carcass or offal. However, differences in composition between groups at the end of weight loss were not significant. During compensatory growth there were few differences between groups in the relative growth rates of protein, fat, ash or water in the whole body, carcass or offal. There were some differences between groups in weights of components at specific BW, carcass weight (CW) and offal weight WW), most notably fat and ash. However, these differences appeared to be transitory, and reflected the composition of that portion of the animal at the start of realimentation, rather than an effect of weight loss which was maintained during compensatory growth. The body, carcass and offal composition of sheep appeared to be resilient to periods of nutritional stress, and tended to return to the "normal" composition expected at that weight. The effects of up to 18 weeks severe undernutrition, resulting in rapid BW loss, were able to be overcome during compensatory growth when feed was offered ad libitum. Compared with developmental growth, nitrogen retention increased during compensatory growth. However, the efficiency of ME utilization was not different during these two periods of growth, although DE requirements for maintenance were lower during compensatory growth, compared with developmental growth. Dry matter intakes (DMI) of treatment groups required up to 13 weeks to return to the DMI of sheep during developmental growth, once ad libitum feeding was resumed. Over their respective growth paths Groups A, B, C, D and E required the same amount of feed to reach 50 kg BW. Wool growth rate (WGR) responded more slowly than BW to changes in level of nutrition, both during weight loss and during compensatory growth. There was a lag phase of at least 30 days. WGR during compensatory growth was reduced and required up to 14 weeks to return to developmental WGR after ad libitum feeding was resumed. Total body water (TBW), estimated from tritiated water (TOH) space in sheep undergoing compensatory growth, was overestimated by at least 20%. TOH space was measured without imposing a period of prior starvation on the sheep, and this may have contributed to the large overestimate. Multiple regression equations including TOH space, BW and a maturity factor (M), were able to explain up to 95% of the variation in chemical composition of the body, but residual standard errors were still high.
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ItemThe behaviour of sheep in narrow lane-ways( 1977)This thesis presents a study into the behaviour of sheep with particular emphasis on sheep movement and behaviour in narrow lane-ways. It is divided into five sections. The first section consists of a review of the behavioural implications associated with domestication. This review topic gives the reader a brief synopsis of previous work and conjecture on the behavioural and physiological responses of sheep. Although this review is only indirectly related to the experimental work it does emphasise the importance and relevance of behavioural studies to the agricultural industry. The second section describes an experiment aimed at investigating some of the factors which affect movement of sheep through races and to provide information required for the design of future work. The movement of flocks of sheep through races (narrow lane-ways) was observed and the effect of (1) forced or voluntary movement (2) whether the sides were open, partially covered or totally covered and (3) flock size, were examined. Differences in the movement of individual sheep were also investigated. Flock size (10 or 20) had very little effect on the movement of sheep in races. When sheep were forced through the race they ran faster, were more bunched and held their heads higher than when moving voluntarily. The race type effect on sheep movement was greatest when sheep were moving voluntarily. This suggests that forcing sheep masked the race type effect. A relatively consistent order of sheep through the race suggests that sheep maintain similar positions when running through races. This effect was reduced when the sheep were forced. Sheep moved faster through open or partially covered races than through totally covered races. They were also more bunched and held their heads higher as the race was increasingly covered. The remaining sections discuss experiments concerned with the evaluation of the current folklore or principles of sheep handling and behaviour. The third section discusses the movement of sheep around corners. The movement of flocks of 20 sheep through races (narrow laneways) incorporating an angle was observed, and the effect of (1) width of race, (2) whether the sides were open or covered and (3) the angle of corner, were examined. Sheep ran faster through races 1.5 m. wide than through races 0.5 m. wide, because they could move as a group rather than being constrained to move in single file. In both narrow and wide races sheep ran faster and were more spread out when the sides were covered, than when the sides were open. Corners acted as an impediment to sheep flow because the spacing between sheep decreased before the corner and increased after it. In wide races the time taken to run through the race increased as the angle of the corner increased. However, in narrow races the corner appeared to have an overall acclerating effect, despite the increased spacing between sheep. The findings in section three have been accepted for publication by the Journal of Applied Animal Ethology. The fourth section discusses the movement of sheep up or down inclines. The movement of flocks of 15 sheep through narrow ramps and of 14 sheep through wide ramps was observed and the effect of (1) movement up or down the ramp (2) whether the floor type was slats, a solid surface or steps and (3) the angle of incline, were examined. In both narrow and wide ramps sheep ran faster and were more bunched when moving up the ramp, than when moving down the ramp. Steep slopes acted as an impediment to sheep flow, slowing the rate of movement of the flock and increasing the spacing between sheep at the end of the ramp. Floor type had no effect on sheep movement in the narrow ramp. In the wide ramp, the solid floor increased the sheep's rate of movement going up the ramp, but decreased it when sheep were descending the ramp. The fifth section discusses the movement of sheep through or into differing light intensities. The movement of flocks of 14 sheep through narrow and wide races (narrow laneways) was observed. A partition across the race allowed the light intensity to be varied independently on each side and the effects of four levels of light intensity i.e. 1.4, 88, 350, and 1,400 lux (dark, low, medium and bright respectively) were examined. The effect of different light intensity on the movement of sheep was not great. There was little evidence to suggest that contrast was important. The results suggest that sheep move more readily through or into brightly lit areas, but that this response is clearly dependent upon the first sheep's behaviour. From the results of these trials, revised "principles" of sheep behaviour have been obtained which have important implications for the design of yards, sheds and races.
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ItemThe pathophysiology of Trichostrongylus colubriformis in sheep surgically modified to incorporate a Thiry-Vella loop( 1977)The results of the current experiment indicate the apparent absence of systemic stimuli in the disease mechanisms of T. colubriformis infection. While infection of Thiry-Vella loops in 2 sheep was associated with severe atrophy and a marked increase in secretory activity of such loops, the remaining intestine in continuity with the alimentary tract (functional intestine) appeared normal. Similarly, per os infection, which produced varying degrees of disorders of functional intestine, was not accompanied by any changes in the secretory function or mucosal morphology (other than those resulting from the isolation procedure) of Thiry-Vella loops. In one severely affected sheep (per os infection), the secretory function of the Thiry-Vella loop was diminished. However, it would appear that the reduction was associated with a water stress rather than being a direct effect of parasitism. The absence of anorexia in loop infected sheep despite the severe lesion might indicate the unimportance of gut pain as a mediator of anorexia in parasitisms. However, this aspect requires further work since the by-pass procedure and the environment in by-passed intestine may diminish the manifestation of gut pain.