School of Agriculture, Food and Ecosystem Sciences - Theses
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ItemBody composition of swamp buffalo (Bubalus bubalis) : a study of developmental growth and of sex differences( 1978)A review has been made of developmental growth and of genetic effects on the body composition of some farm animals. Relationships between chest girth and body weight were studied using sets of data collected in Indonesia from 365 male and 404 female swamp buffalo, each classified to age as having 0, 2-6 and 8 permanent incisors. Linear regressions by which body weight may be predicted from chest girth are presented for each sex-age class. A body composition study, also carried out in Indonesia, was conducted using 12 buffalo bulls and 13 buffalo cows, comprising FBK (Fasted Body Weight; no feed or water for 14 h before slaughter) from 190 to 498 kg or EBW (Empty Body Weight; F minus weight of digests and bladder content) from 158 to 379 kg. Data on HCW (Hot Carcass Weight), HSW (Hot Side Weight), weights of offal components, SMW (Side Muscle Weight) , SBW (Side Bone Weight) , SFW (Side Fat Weight) , SCIW (Side Connective Tissue Weight), weights of SMG (Standard Muscle Groups) and weights of gut tissue components were recorded. The weights of head and tail muscles were also recorded to obtain BMW (Body Muscle Weight) , BBW (Body Bone Weight) , BFW (Body Fat Weight) and BCIW (Body Connective Tissue Weight). The body composition data were analysed by using the variables in the equation: y = axb in logarithmic form (log y = log a + b log x). Comparisons between sexes are being made by using one-sway analyses of co-variance. In the thesis, b values are referred to as growth coefficients or relative growth ratios, and a values as intercepts. (1) Body composition: The apparent and true dressing percentages were not affected by sex and did not change significantly throughout the ranges of FBW and EBW . Both apparent and true dressing percentages are much lower in buffalo than in cattle. At the same FBW or EBN, bulls had less FBW, heavier BBW and BCTW than cows. Bulls had a higher BMW than cows at the same EBW, but both had similar BMW at the same FBW. Sex affected the growth coefficient of head (bulls) cows) and omental fat (cows > bulls) relative to FBW, but it did not affect the growth coefficients of other offal components. Similar results were obtained when offal components were regressed on EBW, apart from the growth coefficient for hide(bulls > cows). At the same EBW, bulls had less blood, heavier head, hide and feet, lighter urogenital tract and alimentary tract than cows. At the same live-weight, the blood, head, feet, hide and alimentary tract appeared to be heavier in buffalo than in cattle. (2) Carcass composition: Sex affected the growth coefficient of SMW relative to HSW (bulls > caws), whereas those for other carcass components were similar between sexes. At the same HSW, bulls had higher SMW and SCIW and lighter SFW than cows (different intercepts), but both had similar SBW. Age (as distinct from erupted incisors) did not affect carcass composition of cows. Within sex comparisons at the same HSW shaved that the buffalo had more muscle than British beef cattle breeds and a similar amount to Bos indicus, Shorthorn cross and Friesian cattle, less fat than cattle, more bone than British beef cattle breeds but similar amount to Friesian cattle and less than Bos indicus cattle.
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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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