bluuebunny/crossref_metadata_2025_split huggingface dataset:
Estimates of genetic parameters of growth rate in sheep with reference to the method of estimation
Authors: Salah E. , Galal E. 
Published: September 2010

There were 563 lambs in the study. They were single Barki lambs born during the period 1961–62 to 1965–66 in Ras El-Hekma Desert Research Station (U.A.R.). All lambs were weighed at birth and at weaning. From 1963–64 onward lambs were weighed nearly every 15 days.Two methods of estimating growth rate were compared:R1 = weaning weight — birth weight/age at weaningand R2 = the regression coefficient of weight on age. The effect of method of estimation on heritabilities and genetic and phenotypic correlations was examined.Heritability estimates of birth weight, R1 and genetic and phenotypic correlations between them were 0·18 ± 0·10, 0·24 ± 0·11, 0·50 and 0·12 respectively. From the data collected during the period 1963–64 to 1965–66 alone the heritability estimates of birth weight, R1 and R2 and the genetic and phenotypic correlations between birth weight and each of R1 and R2 were 0·15 ± 0·14, 0·39 ± 0·20 and 0·39 ± 0·20; 0·84 and 0·96; 0·28 and 0·27 respectively.For preweaning growth rate the method of dividing the gain in weight until weaning by age at weaning was virtually as good a method as using the regression of body weight on age. The correlation between the two methods was estimated as 0·91.
Heat losses from young pigs at three environmental temperatures, measured in a direct calorimeter
Authors: Holmes C. W. 
Published: September 2010

1. A direct calorimeter is described, capable of partitioning the total heat loss from individual pigs into its evaporative and non-evaporative components; tests revealed that the instrument measured non-evaporative heat loss with a coefficient of variation of 3%, and evaporative heat loss with a coefficient of variation of 5·0% at 10° and 20°C, and 5·6% at 30°C.2. Experiments were carried out to measure the differences between heat losses at 20° and 9°C, or at 20° and 30°C, for pigs weighing approximately 26 kg and 64 kg; each measurement lasted 20 minutes and was made after an equilibration period of 3–4 hr.3. Heat loss was proportional to body weight raised to the power of 0·6, under the present experimental conditions, over the range 26–64 kg at 20°C.4. Total heat loss at 9°C was significantly greater than at 20°C for pigs of both sizes; total heat loss at 30°C was smaller than at 20°C for pigs of both sizes, the decrease being significant for the heavier pigs only. Nonevaporative heat loss increased significantly with decrease in temperature. Evaporative heat loss at 30°C was significantly greater than at 20°C. The increases in total and non-evaporative heat losses at 9°C when compared with 20°C, were significantly greater for the lighter pigs than for the heavier pigs. The small decrease in total heat loss at 30°C, compared with 20°C, may have been due to non-attainment of thermal equilibrium at 30°C.5. Values for whole body thermal conductance were calculated from the measurements of non-evaporative heat loss, and these indicated that a change in tissue conductance took place between 20° and 30°C; the mean values at 9°C were 3·78 and 3·15 kcal/°C.m2.hr for the lighter and heavier pigs respectively.6. Evaporative heat loss at 20°C amounted to 280 and 330 kcal/m2. 24. hr for the lighter and heavier pigs respectively. This component of heat loss amounted to 8% and 13% of the total heat loss at 9° and 20°C respectively for all pigs; the corresponding values at 30°C were 32% and 25% for the lighter and heavier pigs respectively. The increased evaporative loss at 30°C was accompanied by an increase in respiratory rate.7. These results agreed well with the results of previous work with groups of pigs, for heat loss at 20°C. Comparisons with that work indicate that the increase in heat loss at 9°C, when compared with 20°C, was greater for individual pigs than for groups of pigs, of both sizes.
The effect of age and live weight on feed conversion and yield of saleable meat of intact Israeli Friesian male calves
Authors: Levy D. , Holzer Z. , Volcani R. 
Published: September 2010

Twelve groups of five Israeli Friesian intact, individually fed, male calves, were slaughtered at different live weights. Commencing with 350 kg, the groups were slaughtered at intervals of 25 kg up to 625 kg live weight. Body and carcass composition data were obtained for each calf, and a feed conversion ratio was calculated.Regression coefficients of age, feed conversion ratio and carcass data on empty body weight, and also the corresponding correlations, were calculated by the equations: y = b + αx for linear and y = bxα for nonlinear regressions.Age increased at a rate very similar to that of empty body weight (α = 1·042). Increase in the amount of feed required to produce unit live weight was much slower (α = 0·045). With increasing empty body weight, dressing percentage and the percentage of kidney, channel and cod fat in the carcass increased moderately (α = 0·011 and 0·004 respectively), the percentage of the external organs decreased moderately (α = −0·010), and the percentage of bone in the carcass decreased very markedly (α = −0·277). The combined effect of these factors was to cause a marked increase in the percentage of saleable meat (α = 0·107) with increasing empty body weight.Results indicate that it is possible to increase the marketing weight of Israeli Friesian male calves considerably without any detrimental effect on carcass composition or economy of production.
Phenotypic aspects of growth and carcass quality in veal calves
Authors: Hinks C. J. M. , Andersen B. Bech 
Published: September 2010

Five hundred and ten Danish Red male calves slaughtered for the production of veal at live weights of approximately 200 kg were used to estimate carcass composition.Regression coefficients expressing the relationships between live weight and carcass components indicated that weight at 6 months of age consisted mostly of muscle development in the breast and hindquarters.Variation in all of the more important growth and carcass attributes was very small, which suggested that selection responses would be difficult to obtain.There was no apparent correlation between growth rate and the muscle, fat and bone components of the carcass. The best single indicator of the muscle content of the carcass was the muscle content of the pistol cut (r= 0·79), which itself involved complicated dissection procedures. Thelongissimus dorsiarea provided relatively little information, and none of the body measurements, apart from the leg circumference, were strongly related to carcass composition.The predictive value of many combinations of traits was examined. The best of them accounted for 90% of the variation in muscle content, but when the pistol cut was excluded, none of the multiple correlation coefficients exceeded 0·8.
Factors affecting voluntary feed intake in pigs. 3. The effect of a period of feed restriction, nutrient density of the diet and sex on intake, performance and carcass characteristics
Authors: Cole D. J. A. , Duckworth J. E. , Holmes W. , Cuthbertson A. 
Published: September 2010

1. Over the weight range 23–50 kg live weight, pigs were fed either ad libitum or to a restricted scale. From 59 to 91 kg live weight, eight pairs of barrows and eight pairs of gilts were fed on each of two diets varying in nutrient density. The effects of feed restriction, nutrient density of the diet and sex on voluntary feed intake, performance and carcass characteristics were studied.2. Pigs which had been restricted grew more slowly and contained less fat and more lean at 50 kg live weight.3. When restricted pigs were offered feed ad libitum from 59 to 91 kg live weight they ate more and had higher daily intakes of digestible energy than pigs liberally fed in early life.4. There was evidence of compensatory growth in pigs which had received the restricted diet, but there was no significant difference in feed utilization between restricted and ad libitum pigs. It was concluded that the compensatory growth was largely the result of increased appetite.5. Pigs finally fed on a low energy diet, in comparison with those on a high energy diet, ate more feed but less digestible energy indicating that appetite was physically limited. Efficiency of conversion of digestible energy to live weight was similar on both treatments. A higher proportion of acetic acid was produced in the caecum of pigs fed the low energy diet. Pigs receiving the low energy diet had lower killing-out percentages not entirely caused by differences in the weight of the gut and its contents. The carcasses of pigs on the low energy diet were leaner than those on the high energy diet.6. Barrows consumed more digestible energy per day than gilts, required more feed and digestible energy per unit live-weight gain, had lower killing-out percentages, shorter carcasses, larger backfat measurements and smaller eye-muscle areas as estimated by A × B measurements. Barrow carcasses contained less dissected lean and more fat than gilts' carcasses.7. The results are discussed in relation to other work and it is concluded that voluntary feed intake is influenced by the nutrient density of the diet and the level of energy requirement of the pig, which may be affected by previous nutritional history.
The performance of beef cattle given diets of barley supplemented with either vegetable protein or non-protein nitrogen
Authors: Walker T. , Kay M. , Preston T. R. , McDonald I. , MacLeod N. A. , Macdearmid A. 
Published: September 2010

1. Four growth trials were carried out with 297 group-fed steers given diets based on barley, minerals and vitamins, unsupplemented or supplemented
with either soya bean meal or various sources of non-protein nitrogen.2. Steers given unsupplemented barley (11% crude protein in dry matter) had inferior growth rates up to 300 kg live weight but thereafter were equal to those given barley supplemented with urea in the drinking water or soya bean meal.3. There were no significant differences in the growth rates of steers given barley supplemented with soya bean meal and those given barley supplemented with ammonium and mineral salts of formic acid or a mixture of acids (predominantly acetic).4. In two out of three trials, tenth-rib joints from steers given barley supplemented with ammonium salts of mixed acids contained less fat and more protein and water than those from steers given barley supplemented with soya bean meal or proprietary protein supplements.5. A number of possible explanations for the apparent carcass differences is discussed.
Equilibrium weight in relation to food intake and genotype in twin cattle
Authors: Taylor C. S. , Young G. B. 
Published: September 2010

Twenty-two Ayrshire twin female cattle were kept for up to seven years of age on six equally spaced levels of constant food intake, ranging from 35 to 140 lb per week of a complete pelleted diet. Analysis was confined to the period between 5 and 7 years when growth had practically ceased and equilibrium maintenance requirements could be determined.Equilibrium weight maintained was directly proportional to the level of constant food intake.This relationship obtained by controlling food intake was significantly different from the 0·73 power relationship that applies across species. In establishing the present relationship, systematic genetic differences were excluded, and this is probably the main condition required for weight eventually maintained to be proportional to food intake. In contrast, the
well-established proportionality of food intake to metabolic weight is essentially based on a species comparison and is thus due almost entirely to genetic differences.A mathematical model is given which combines (1) the genetic relationship of proportionality of voluntary food intake to mature metabolic weight and (2) the nutritional relationship of proportionality of equilibrium weight maintained to level of constant food intake. The model is then used to partition variation into systematic and random components.The experiment provides some indication of the extent of individual variation in efficiency of maintenance within breeds, the amount which is genetic, and the repeatability of this efficiency from age to age. Some information is also provided on variation in voluntary food intake, mature weight maintained and efficiency of maintenance on ad libitum feeding.Methods of estimating efficiency of maintenance using ‘feed and weigh’ techniques, selection for efficiency of maintenance, the correlated response in mature weight, and selection for relative food capacity are briefly discussed.
The effect of level of feeding on the digestibility of diets for sheep and cattle
Authors: Leaver J. D. , Campling R. C. , Holmes W. 
Published: September 2010

SUMMARY1. In the first experiment, the digestibility of diets containing ratios of 1:1 and 1:4 hay to concentrates was determined at five levels of feeding in castrated male sheep. With diet 1.1, increasing the daily dry matter intake from 600 to 1400 g resulted in a linear decline in organic matter digestibility from 74·4 to 68·6%. The same increase in level of feeding led to a curvilinear decline in the organic matter digestibility of diet 1.4 from 83·0 to 75·9%.2. In a similar way the crude fibre digestibility of the diets declined as food intake increased. Also the increase in level of feeding caused a decrease in the mean retention time of stained hay in the alimentary tract.3. In a second experiment the digestibility of long dried grass offered ad libitum to eight dry and eight lactating cows was measured and compared with the digestibility of similar dried grass offered at maintenance level and ad libitum to eight castrated male sheep.4. On a metabolic live-weight basis (kg W0·73), the lactating cows ate 34% more organic matter than the dry cows and the mean voluntary intake of sheep was only 54% of the intake of dry cows.5. The organic matter digestibility for the dry cows was 1·9 units higher than that of the lactating cows and at ad libitum intake the organic matter digestibility for the sheep was 5·6 and 3·7 units lower than that of the dry and lactating cows respectively. The results are discussed in relation to the validity of extrapolating results obtained with sheep to cattle, and with non·lactating to lactating animals.
Cold Exposure of Southdown and Welsh Mountain Sheep. 2. Effects of breed, plane of nutrition and previous acclimatization to cold upon skin temperature, heart rate, shivering and respiration rate
Authors: Sykes A. R. , Slee J. 
Published: September 2010

SUMMARYShorn Southdown and Welsh Mountain sheep on high or maintenance levels of nutrition were subjected to two acute (−20°C; 4 mph wind) cold exposures in climate chambers. Before and between exposures the sheep were kept in either a cold (+8°C) or a thermoneutral (+30°C) environment.1. At +8°C, all the sheep shivered and showed sustained vasoconstriction and elevated heart rates.2. At + 30°C, heart rates, skin temperatures on the extremities and muscular tone were all consistently higher in sheep which had previously been kept at +8°C.3. During cooling, the onset of vasoconstriction and increase in heart rate were both delayed in sheep previously kept at + 8°C.4. These effects (2, 3) were retained for at least 2 days but less than 12 days after the sheep returned to thermoneutrality. They decayed faster than the increased resistance to body cooling produced simultaneously in the same sheep (Sykes and Slee, 1969), since this was still detectable after 2 weeks.5. Breed differences were mainly small.6. It was concluded that acclimatization induced by chronic cold exposure was associated with a temporary increase in basal metabolic rate.
The effects of pattern of feed distribution during the reproductive cycle on the performance of sows
Authors: Lodge G. A. 
Published: September 2010

SUMMARYThree groups of 10 Large White gilts were allocated on a littermate basis to 3 feeding regimes, for 3 successive pregnancies and lactations, to provide the following daily allowances:
(A) 6 lb feed per day in pregnancy and 2 lb plus 1 lb per pig suckled in lactation; (B) the same total as (A) but given as 4 lb per day in regnancy and 6 lb plus 1 lb per pig suckled in lactation; (C) a lower overall allowance distributed during pregnancy as 5 lb during weeks 1, 2, 15 and 16, 3 to 5 lb during weeks 3, 4, 13 and 14 and 2 lb during weeks 5 to 12, and during lactation increasing by 1 lb per day to appetite or a maximum of 26 lb at the 21st day, and then decreasing by 1 lb every alternate day to a minimum of 5 lb. Creep-feed was provided ad libitum from 3 weeks of age until weaning at 8 weeks of age.
Differences between groups in litter size and weight at birth were not significant but the combined measure of litter weight was significantly lower in C than in A and B (P<0·05); litter size (P<0·05) and litter weight (P<0·01) but not individual pig weight increased with parity. At 3 and 8 weeks of age there were no significant differences between groups in size or weight of litters or in individual pig weights. Pigs of Group C sows consumed significantly more (P< 0·001) creep feed (7 lb per head) than those of Groups A and B.
Sows of Group A gained double the weight of Groups B and C during pregnancy (P<0001) and lost significantly more (P<0·001) during lactation; Groups B and C did not differ significantly in either respect. Efficiencies of feed conversion (EFC) of total food into total weight by sow and litter were poorest in Group A and best in Group C.
Ammonium salts of fatty acids for milk production 2. The effect of feeding a salt solution containing ammonium acetate on the yield and fatty acid composition of Jersey milk fat
Authors: Hutton K. , Prescott J. H. D. , Seeley R. C. , Armstrong D. G. 
Published: September 2010

SUMMARY1. The effect of feeding a salt solution containing ammonium acetate on the yield and fatty acid composition of cows' milk fat has been studied.2. The trials involved eighteen lactating Jersey cows. In the first trial one group of 5 cows was fed the treatment diet throughout an experimental period of 10 weeks and another group of 5 cows acted as controls. In the second trial which extended over four 28-day periods, two groups of 4 cows spent alternate periods on treatment or control diets. The overall results of the two trials were in agreement.3. The outputs of C4-C14acids and of palmitic acid per kg of milk yielded were greater than the intakes. The output of C18acids was less than the intake per kg of milk yielded. These observations were noted on both treatment and control.4. Treatment resulted in an increased secretion of C4-C14acids and of palmitic acid and a decreased secretion of C18acids per kg of milk yielded.5. The results have been discussed in the light of present knowledge concerning the synthesis of fat in the mammary gland.
The effect of level of feed intake in pregnancy and in lactation upon the productivity of sows
Authors: Elsley F. W. H. , Bannerman Mary , Bathurst E. V. J. , Bracewell A. G. , Cunningham J. M. M. , Dodsworth T. L. , Dodds P. A. , Forbes T. J. , Laird R. 
Published: September 2010

SUMMARYEight research and teaching centres have co-operated in an experiment involving 132 sows. Six treatments were used, combining three levels of feeding in pregnancy with two in lactation. Pregnancy treatments were High 3−2 kg meal/day, Medium 2·4 kg/day and Low 1·6 kg/day; in lactation either a high level, 4·1 kg plus 0·2 kg/pig (h) or a medium level, 2·3 kg plus 0·2 kg/pig (m) were given. The sows were maintained on the same nutritional regime for three parities although inevitably some sows were lost before the completion of the trial. Sow live-weight gains in pregnancy were directly related to feed intake; in lactation, losses in sow live weight were dependent on gains made in the previous pregnancy and on the level fed while suckling. After the first parity, in which animals fed the low level in pregnancy tended to produce larger litters (though the difference was not significant), there were no differences in numbers born attributable to treatments.Increases in the feed intake of sows in pregnancy resulted in consistent and significant increases in the weight of the pigs at birth. This increase in birth weight also resulted in an increase in weight at weaning in the second and third parities. Level of feeding in lactation, which had a highly significant effect on sow live weight, had much less influence on weaning weights of pigs. There were no consistent pregnancy × lactation interactions, the effects of treatments in the two phases being additive.An assessment is made of the relative efficiency of the six treatments and the value of the experiment is discussed in relation to other studies concerned with sow nutrition.
Single cereal diets for bacon pigs 1. The effects of diets based on barley, wheat, maize meal, flaked maize or sorghum on performance and carcass characteristics
Authors: Cole D. J. A. , Clent E. G. , Luscombe J. R. 
Published: September 2010

SUMMARYTwo experiments were carried out to compare the performance and carcass quality of pigs given diets based on barley, wheat or maize meal, and another two experiments comparing these cereals, flaked maize and sorghum. In general, differences in the utilization of feed for live-weight gain could be related to differences in the digestible energy content of the cereals used in the diet, although in some experiments pigs behaved atypically on individual diets. Flaked maize was consistently inferior to the other cereals in the efficiency of conversion of its digestible energy, possibly because of its poorer amino acid balance and its low levels of lysine and tryptophan in relation to energy. Differences between experiments in the performance of pigs fed on the various diets are also discussed. Differences between treatments in killing-out percentage and predicted lean percentage were small, and carcasses of pigs from all treatments were acceptable for bacon curing.
Studies on colostral and milk whey proteins in the sow 1. The transition of mammary secretion from colostrum to milk with natural suckling
Authors: Bourne F. J. 
Published: September 2010

SUMMARYA dramatic fall in the colostral whey proteins of nine sows occurred within 24 hr following the birth of the first piglet. The mean levels fell from 19·6 g/100 ml to 4·1 g/100 ml, 50% of this fall occurring within 4 to 6 hr. It is suggested that as early-born piglets will be able to obtain colostrum of a much higher protein concentration this may give them some physiological and immunological advantages over later-born littermates.