This study aimed to identify genetic evaluation models (GEM) to accurately select cattle for milk production when only limited data are available. It is based on a data set from the Pakistani Sahiwal progeny testing programme which includes records from five government herds, each consisting of 100 to 350 animals, with lactation records dating back to 1968. Different types of GEM were compared, namely: (1) multivariate v. repeatability model when using the first three lactations, (2) an animal v. a sire model, (3) different fixed effects models to account for effects such as herd, year and season; and (4) fitting a model with genetic parameters fixed v. estimating the genetic parameters as part of the model fitting process. Two methods were used for the comparison of models. The first method used simulated data based on the Pakistani progeny testing system and compared estimated breeding values with true breeding values. The second method used cross-validation to determine the best model in subsets of actual Australian herd-recorded data. Subsets were chosen to reflect the Pakistani data in terms of herd size and number of herds. Based on the simulation and the cross-validation method, the multivariate animal model using fixed genetic parameters was generally the superior GEM, but problems arise in determining suitable values for fixing the parameters. Using mean square error of prediction, the best fixed effects structure could not be conclusively determined. The simulation method indicated the simplest fixed effects structure to be superior whereas in contrast, the cross-validation method on actual data concluded that the most complex one was the best. In conclusion it is difficult to propose a universally best GEM that can be used in any data set of this size. However, some general recommendations are that it is more appropriate to estimate the genetic parameters when evaluating for selection purposes, the animal model was superior to the sire model and that in the Pakistani situation the repeatability model is more suitable than a multivariate.

1. An experiment is described in which 194 pairs of piglets on 10 commercial farms were reared out of doors with access to soil, either on free range or in field pens. One piglet from each pair received 200 mg. of iron as a parenterally administered iron dextrin complex. The soil type and the iron content of the soil were determined on each farm.

2. During the first 8 weeks of life, the treated piglets showed a small but significant positive growth response of 1–2 lb. (3·0%). The response was greater (2·1 lb.) in piglets reared in field pens, but was non-significant in those reared on free range.

3. Differences in blood haemoglobin levels, mortality and the incidence of runt piglets were not significant.

4. Total body iron increased during the first 3 weeks of life by a mean of 339 mg., of which approximately 295 mg. appeared to be derived from the soil.

The results of a previous experiment suggested that a scale of feeding at about 60% of full-feed level from weaning onwards could result in a high incidence of infertility in gilts, but numbers were insufficient to confirm this. The present trial was carried out, therefore, with 18 Large White gilts per treatment fed to scales rising from either 1·4 lb. meal per day at 36 lb. live-weight to 5·0 lb. at 200 lb. live-weight, or from 1·9 lb. to 6·5 lb. over the same weight range. Average growth rate of the low-plane gilts was 76·5% of that of the medium-plane group but none of the low-plane gilts failed to conceive.

A study was carried out on data collected between 1970 and 1979 on the crossbreeding of cattle in Vom using British Friesian, Brown Swiss and Jersey bulls. Only crossbreeding involving Friesian bulls was successful. There were progressive increases in lactation yield, yield per day of lactation length, lactation length, daily fat yield, birth weight and calving interval in the grades with increases in the Friesian contribution. The daily fat concentration however decreased with the increase in Friesian proportion. Most of the genotypes namely, pure White Fulani, 0·5 Friesian: 0·5 White Fulani; 0·75 Friesian: 0·25 White Fulani, 0·875 Friesian: 0·125 White Fulani and pure Friesian calved regularly each year. Phenotype correlations between lactation length and yield for most of the genotypes were high, positive and significant.

To reduce competition with human-edible feed resources, it is of interest to incorporate by-products from the food industry in animal feeds. The current research investigated the effect of including increasing amounts of tofu by-product (TF) in practical pig diets on animal performance, nitrogen balance and ammonia emissions from manure. Two experiments were conducted including a control diet without TF, containing 160 g/kg dietary non-starch polysaccharides (NSPs) and three diets including 122, 246 and 360 g TF/kg DM (TF122, TF246 and TF360, respectively) to reach 220, 280 and 360 g/kg NSP. All diets had the same level of CP and protein digestible in the small intestine which particularly was realized by replacing rice bran with TF. Animal performance was assessed in a first experiment with 40 growing barrows with initial BW of 26.6 ± 1.80 kg (M ± SD) being allocated to the 4 treatments, during 2 growth phases (i.e. until 50 kg BW and from 50 to 80 kg BW). In the growth phase until 50 kg, feed intake and average daily gain (ADG) were linearly reduced by dietary TF inclusion, while this negative impact disappeared during the second growth phase (50 to 80 kg BW). Tofu by-product inclusion even positively affected the feed conversion ratio during this second growth phase (3.4 to 2.7 kg feed/kg ADG for 0 to 360 g/kg dietary TF). Over the entire growth period, performance and feed intake were negatively affected at the highest dietary TF level. Experiment 2 was conducted to assess digestibility, nitrogen balance and ammonia emission from manure. For this purpose, 16 pigs with BW of 62.8 ± 3.6 kg (M ± SD) were assigned to either 1 of the 4 treatments. There was no difference in total tract apparent digestibility of dietary organic matter or CP, while NDF digestibility increased with increasing TF level, suggesting increasing importance of the hindgut fermentation when digesting diets with increasing TF levels. Nevertheless, this was not reflected in increasing levels of faecal volatile fatty acids or purines, nor in reduced manure pH. As a result, ammonia emission from slurry was not reduced through dietary TF inclusion, despite the linear decrease in urinary nitrogen. In conclusion, TF can be included in pigs’ diets up to an inclusion rate of 25% without risk of impaired animal performance; however, this dietary strategy fails to mitigate ammonia emission from slurry.

The effects of diets containing variable percentages of roughage and moisture on depot fats were studied. Treatments were 25 and 45% roughage in the complete fattening diet, and 10, 50 and 75% moisture content of the diets. Depot fats collected post-slaughter from kidney, pelvic, ruminal, cod and trim fats in the carcass (mostly subcutaneous and some intermuscular) were weighed and analysed for their fatty acid composition.

Increasing the quantity of roughage in the diet (from 25 to 45%) significantly decreased ruminal fat deposition. Moistening the feed significantly increased the deposition of kidney, pelvic and cod fat, and significantly reduced the deposition of fat trim in the carcass. The content of unsaturated triglyceride fatty acids was significantly greater in calves fed on the 25% roughage diet. Calves fed on the soaked diets had significantly higher contents of unsaturated fatty acids than the controls.

The content of unsaturated acids was greater in cod fat and carcass trim than in kidney, pelvic or ruminal fat.

Hydrogenation in vitro of fatty acids by ruminal micro-organisms decreased with increasing level of moisture in the diet.

It is suggested that the increased unsaturated fatty acid content of the depot fats of animals fed on soaked diets might be due to a reduction in the hydrogenation of dietary lipid by rumen micro-organisms.

Nutritional stressors may cause negative effects on animal health and growth and lead to significant economic impact. Adipose tissue is an endocrine organ producing, mediators and hormones, called adipokines. They play a dynamic role in body homeostasis and in the regulation of energy expenditure, interacting with feeding behavior, hormones and growth factors. This in vitro study aimed to investigate how nutritional conditions and growth hormone (GH) can influence nitric oxide (NO) production and the expression and secretion of three important adipokines, that is leptin, interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α), by swine adipocytes. In our experimental model, mesenchymal stem cells from omental adipose tissue were induced to adipogenic differentiation. After differentiation, adipocytes were incubated for 24 h (T0) with DMEM/Ham’s F12 (group A) or DMEM/Ham’s F12 salts (group B), a DMEM/Ham’s F12 formulation deprived of nutritional components. Primary adipocyte cells were also co-cultured for 4 h (T+4) or 12 h (T+12) with or without anterior pituitary slices. To stimulate GH secretion by pituitary cells, growth hormone releasing hormone at 10−8 M was added at the start of the incubation times (4 or 12 h). At T0, T+4 and T+12, NO production, leptin, IL-6 and TNF-α expression and secretion were measured. NO increased (P<0.05) up to twofold in restricted culture conditions. Deprived medium and coincubation with anterior pituitary positively influenced leptin secretion and expression. TNF-α was expressed and secreted only in deprived culture condition groups (B, B1 and B2). Nutrients availability and pituitary co-culture did not affect IL-6 expression and secretion. Our study shows an endocrine function for porcine adipocytes. In our model, adipocytes readily responded to nutritional inputs by secretion of molecules affecting energy balance. This secretion capacity was modulated by GH. Improving our knowledge of the role of adipocyte in the endocrine system, may lead to a more complete understanding of regulating energy balance in swine.

Sixty Landrace × Large White gilts were allocated at random to one of three treatments. Treatment A gilts were fed 16 mg allyl-trenbolone once a day for 18 days. Treatment B gilts were fed 20 mg allyl-trenbolone per day for 18 days. Treatment C gilts were controls. The gilts were allocated to treatment at 111·3 ± 1·91 kg live weight, moved to a pen with individual feeders and put into groups of four gilts to a pen with a sexually mature boar in the adjacent pen. Treatment A and B gilts were tested for heat with a boar for 20 min each day beginning on the day after the last allyl-trenbolone feed. Treatment C gilts were tested with a boar in the same way after allocation. The time from the last allyl-trenbolone feed to oestrus for treatments A and B was 7·05 ± 0·44 and 8·4 ± 0·49 days. The time from the beginning of heat detection to oestrus for group C gilts was 22·4 ± 4·5 days. At oestrus, all gilts were mated twice on successive days with a fertile boar. The mean litter size at farrowing for treatment A was 9·1 ± 0·62; B, 11·2 ± 0·75 and C, 9·3 ± 0·65 piglets born alive (P < 0·05). It is concluded that giving 20 mg of allyl-trenbolone for 18 days to groups of peripubertal gilts is a very effective means of controlling oestrus and ovulation.

The effects of 18 buffalo sires, used in 2 years of a progeny-testing programme, on the subsequent lactation performances of their mates, were investigated from a study of 685 lactation records. The traits studied were: milk production, lactation length, length of post partum anoestrus, number of services per conception and length of service period (calving to conception). Parity of calving and sire had a significant effect on 305-day milk yield and lactation length of the mates. Between the 2 years, the sires did not differ for any of the traits of their mates. Although the breeding value of the sires, high or low, did not differ significantly, the sires with high breeding value tended to depress the milk production in the subsequent lactation of their mates and vice versa (r= −0·05). The birth weight of the calves significantly affected milk production. It was concluded that all methods of sire evaluation are likely to be biased by the effect of sires.

The effects of freeze-branding young beef animals using two coolants were investigated and an attempt was made to avoid hide damage.

1. Branding with irons cooled in liquid nitrogen gave good markings but resulted in severe hide damage.

2. CO2-branding caused much less hide damage but gave fewer legible brands.

3. Legible brands with both coolants always resulted in some marking of the hide.

4. Branding on the jaw provided a satisfactory means of identification without loss of hide value.

Artificial insemination of ewes has become commercially available in Britain on a small scale over the last few years. It allows the farmer to benefit from MLC recorded rams which have been selected for growth rate and more recently for carcass quality. However, proximity to an A.I. centre is an important consideration as A.I. of ewes requires the use of fresh semen. Frozen semen has not vet achieved the quality and reliability necessary on a commercial scale. Insemination is carried out at a fixed time after the removal of Intra-vaginal pessaries and an injection of Pregnant Mare Serum Gonadotrophin (PMSG). Synchronisation of oestrus using sponges and PMSG adds to the cost of using a commercial A.I. service. If A.I. is not used then one ram per ten ewes is necessary for a synchronised mating which either requires a ram sharing group or considerable financial investment if rams of equivalent quality to those used in A.I. centres are to be purchased.

Smith (1986) identified the theoretical potential of multiple ovulation and embryo transfer (MOET) to increase the rate of genetic improvement within nucleus sheep breeding flocks by upto 100%. The likely genetic benefits of MOET arise from the potential to overcome limits to female reproduction thus allowing increased selection intensity and reduced generation intervals among females. The present study was conducted to evaluate the potential for MOET from 18 month-old maiden ewes (gimmers) in comparison with aged donor ewes.

In October 1991, a group of twenty 18-month old ewes and twenty aged ewes (3.5 year-old) were synchronised into oestrus using intravaginal pessaries containing 45 mg Cronolone (Chronogest, Intervet Laboratories Ltd.) inserted for 12 days. Superovulation was achieved using 20 i.u. of ovine follicle stimulating hormone (Ovagen, Immuno-Chemical Products N.Z. Ltd) given in eight equal doses at 12-hourly intervals starting 58 hours before progestagen pessary withdrawal.

The use of molecular genetic information in the evaluation of livestock has become more common. This study looks at the efficacy of using such information to improve the genetic evaluation of a rare breed of dual-purpose cattle. Data were available in the form of pedigree information on the Gloucester cattle breed in the United Kingdom and recorded milk and beef performance on a small number of animals. In addition, molecular genetic information in the form of multi-marker, multiple regression results converted to a 1 to 10 score (Igenity scores) and 123 single nucleotide polymorphism (SNP) genotypes for 199 non-recorded animals were available. Appropriate mixed-animal models were explored for the recorded traits and these were used to calculate estimated breeding values (EBV), and their accuracies, for 6527 animals in the breed’s pedigree file. Various ways to improve the accuracy of these EBV were explored. This involved using multivariate BLUP analyses, genomic estimated breeding values (GEBV) and combining Igenity scores with recorded traits in a series of bivariate genetic analyses. Using the milk recording traits as an example, the accuracy of a number of traits could be improved using multivariate analyses by up to 14%, depending on the combination of traits used. The level of increase in accuracy largely corresponded to the absolute difference between the genetic and residual correlations between two traits, but this was not always symmetrical. The use of GEBV did not increase the accuracy of milk trait EBV owing to the low proportion of variance explained by the 101 SNPs used. Using Igenity scores in bivariate analyses with the recorded data was more successful in increasing EBV accuracy. The largest increases were found in genotyped animals with no recorded performance (e.g. a 58% increase in fat weight in milk); however, the size of the increase depended on the level of the genetic correlation between the recorded trait and the Igenity score for that trait. Lower levels of improvements in accuracy were seen in animals that were recoded but not genotyped, and ancestors which were neither genotyped nor recorded. This study demonstrated that it was possible to improve the accuracy of EBV estimation by including Igenity score information in genetic analyses but it also concluded that increasing the level of performance recording in the breed would be beneficial.

In a multibreed experiment 306 females from 25 British breeds of cattle were given a standard pelleted diet ad libitum. Correlations of food conversion efficiency (FCE) with body weight, weight gain, and food intake were studied over 12-week and longer periods from 12 to 72 weeks of age. Inter-age correlations of FCE with itself and the other traits were also studied over age intervals separated by 12, 24, 36 and 48 weeks. The between-breed correlations were genetic while the within-breed correlations were phenotypic.

Between breeds, FCE measured over the full age range from 12 to 72 weeks appeared to be very highly correlated with FCE measured over the 12-week period between 24 and 36 weeks of age. Correlations of 12 to 72 week FCE with traits not requiring measurement of food intake were much lower, being at most 0·77 for weight gain, 0·73 for weight gain per unit body weight and 0·57 for body weight. The pattern of correlations implied that over constant age ranges the larger faster-growing breeds with high intakes tended to be more efficient; however, these correlations were generated primarily at early ages between 12 and 36 weeks and FCE at later ages could not be predicted from other traits measured at earlier ages. Nevertheless, between-breed selection to improve FCE by indirect selection on body weight and weight gain could be effective but there would appear to be no advantage in waiting beyond 1 year of age.

Within breeds, correlations of 12 to 72 week FCE with FCE measured over 12-week periods increased with age from 0·24 to 0·61. Correlations of FCE with weight gain in the same 12-week periods were quite high (0·49 to 0·89) and those with weight gain per unit weight were invaribly higher (0·68 to 0·90). However, as a predictor of FCE in any subsequent period, weight gain per unit body weight was poor and weight gain of no value whatsoever. There was no strong association of FCE with body weight.

The effects on herbage intake of changes of herbage mass associated with different stocking rates were studied in Greyface (Border Leicester × Scottish Blackface) ewes in the autumn. Intake was measured in 5-day periods in late September (PI), late October (P2) and late November (P3) on two established, perennial ryegrass/white clover swards (SI and S2). Both swards had previously been variably stocked to produce areas with a range in herbage masses, some of which were grazed continuously (G) at stocking rates declining from 18 to 6 ewes per ha.

Intake was also measured in P2 and P3 on other areas of the swards which were ungrazed for 6 weeks in September and October (C) and then stocked at 18 ewes per ha. Intakes of dry matter, organic matter and digestible organic matter were 16 g, 10 g and 7·5 g/kg live weight, respectively. Organic matter digestibility was 075 in PI and P2 but declined in P3.

Differences in herbage intake and digestibility arose largely because of differences between the swards in herbage mass, sward height and sward density. Ewes in condition scores > 3·00 in early September had lower intakes at all times than did thinner ewes. Changes in sward management associated with different strategies of use had little long-term effect on herbage intake. Keywords: digestibility, herbage, sheep, stocking rate.