The native fat-tailed Awassi and the imported German Mutton Merino (GMM) sheep are well adapted to semi-arid conditions (Degen, 1977; Degen and Shkolnik, 1978). This enables these sheep to graze large areas of the Negev Desert in Israel that is marginal for farming. However, under extensive conditions both these sheep breeds yield low lamb crops producing fewer than 1·0 lamb per ewe per year.

Three types of straw were used, a spring barley (variety Corgi) untreated (UC), ammonia-treated Corgi (AC) and an ammonia-treated winter wheat (variety Longbow) (AW). Each straw was included in a complete diet containing either 350 (L), 450 (M) or 550 (H) g/kg straw. The other principal ingredients were rolled barley, molassed sugar-beet pulp and fish meal. Hereford cross steers approximately 16 months old and weighing 350 kg live weight were given the diets ad libitum in both a main trial lasting 80 days, to assess intakes, live-weight gains and food efficiency, and in a subsidiary trial to measure in vivo apparent digestibility.

The live-weight gains during 80 days for steers given the UC diet at L, M and H inclusion were 117, 102 and 0·70 kg/day respectively. The respective live-weight gains for AC were 1·32, 1·27 and 1 02 kg/day and for AW 1 ·26, 1 ·20 and 0·95 kg/day.

While experimental comparisons were terminated at 80 days when the first steers were slaughtered, all except five with the lowest growth rate reached the target fat class for slaughter before 6 months on the diets. While differences in intake and performance between steers given the straws closely reflected differences in degradation characteristics determined by in sacco measurements, the increase in in vivo apparent digestibility between untreated (0·510) and treated (0·545) was small. It is concluded that a large proportion of high quality or treated straw can be incorporated and utilized in diets for finishing cattle.

Heating oils and fats may lead to cyclization of polyunsaturated fatty acids, especially those showing multiple double bonds like linolenic acid. Cyclohexenyl and cyclopentenyl fatty acids are subsequently present in some edible oils and these were suspected to induce metabolic disorders. When fed during gestation in the rat, cyclic fatty acids were historically reported to induce high mortality of the neonates. Nevertheless, none of these studies have been performed with cyclic fatty acids fed as triacylglycerols, limiting the nutritional value of the conclusions. Therefore, we assessed the toxicity of a diet containing 0.7% of cyclic fatty acids fed as triacylglycerols during gestation and the first days of life in the rat. In this work, we report no deleterious effect of cyclic fatty acids in the mothers and neonates. However, cyclic fatty acids induced a tremendous insulinopenia in the mothers and pups that was associated with the reduction of food intake in the gestating females. Such a finding may be a plausible explanation for the adverse effects of cyclic fatty acids observed previously with higher doses of cyclic fatty acids. Based on present data, on previous ones showing elimination of cyclic fatty acids, and considering their low amounts in the diet, we suggest that cyclic fatty acids formed from cyclization of linolenic acid are not a major concern for human safety.

This paper describes a two-part study evaluating the use of growth hormone (GH) response to infusions of somatostatin (SRIF) and GH-releasing factor (GRF) as an indicator of genetic merit in dairy cattle. The first part of the study involved the development of a standard test procedure. This was achieved in two sub-trials, the first testing three SRIF doses, 0·6, 3·0 and 15 µg/kg per h, given over an infusion length of 3 h. The second involved infusing 3·0 μg/kg per h SRIF for either 20 min, 1 h or 3 h. The GH response was measured in serum during the infusion and for 2 h following cessation, during which time a rebound response in GH occurred. As a consequence of these trials, a total of 40 British Friesian calves from two lines genetically divergent for yield traits were infused with 3·0 μg/kg per h for a period of 1 h and at the end of the infusion given 0·1 μg/kg GRF. Five hours later, GRF was administered without SRIF. The protocol was repeated on 2 days consecutively. Results suggested that calves of high merit had lower SRIF-induced baselines than their low-line contemporaries. There were no differences in the GH concentrations immediately following GRF administration, either with or without SRIF. The results from this trial, together with previously published work, indicated that calves selected for high milk fat plus milk protein production may be more sensitive to SRIF such that GH is regulated by lower concentrations of SRIF. However, the practical use of GH response to SRIF as an indicator of genetic merit for dairy cattle may be limited because of logistical difficulties in implementation.

Weaner Hampshire × Landrace × Large White (Hampshire cross) and Landrace × Landrace × Large White (Landrace cross) pigs were given combinations of three diets differing in crude protein content (high: H, low: Land very low: vl). Hampshire cross pigs at 90 kg, both under ad libitum and restricted feeding had greater rates of gain and eye muscle measurements and shorter carcasses than Landrace cross pigs, but were fatter after ad libitum feeding and more efficient food converters after restricted feeding. The HLL treatment led to improved gain and food conversion compared to the LLH or LLL treatment, whereas the LLH treatment led to larger eye muscle measurements. The LvlH treatment led to greater efficiency and eye-muscle area than treatment Lvlvl at 114 kg. An economic analysis was carried out to assess the relative profitability of slaughtering at a range of live weights. Curves were fitted to the data on food intake and live weight. Values were assumed for major costs, and a seven-day interval was allowed between batches of pigs. The calculations indicated that the H diet led to a slight increase in monetary return per pig per day when it was given in the post-weaning period to pigs fed to a scale. Although the Hampshire cross pigs showed a response to the H diet in the finishing period when slaughtered either at 90 or 114 kg, their calculated return was not increased. Ad libitum feeding led to a greater return for heavy but not, on average, for bacon pigs. Maximum return occurred at slaughter between 70 and 115 kg live weight and was only margin-ally greater for restricted baconers at 90 kg than for ad libitum heavy pigs at 110–115 kg. However, return as a percentage of working plus fixed capital was greater for baconers, but the ratio rose throughout the range of hypothetical slaughter weights in both groups. In-clusion of the cost of borrowing money had a negligible effect on the slaughter weight for maximum return with pigs managed in batches.

The objective of this study was to determine the levels of catecholamines and their relationship to beef quality in Nguni steers fed on Acacia karroo leaves. A total of 30 19-month-old steers were randomly assigned to A. karroo leaves (AK), sunflower cake (SF) and the control with no supplement (CN) diets. The AK and SF diets provided the steers with an additional 150 g of protein per day for 60 days. Catecholamine levels were determined from urine samples collected from each steer before and after slaughter. The Musculus longissimus thoracis et lumborum was sampled for selected meat quality measurements. Nguni steers on the CN diet had higher (P < 0.05) concentrations of post-mortem urinary norepinephrine and dopamine compared with those that received the AK and SF diets. Norepinephrine was negatively linearly related (P < 0.05) to the Warner–Bratzler shear force value of meat aged for 21 days and cooking loss of meat aged for 2 days (CL2) in steers that were given the SF diet. Meat pH and drip loss values were inversely related (P < 0.05) to epinephrine concentration in steers that received the AK diet. Dopamine concentration was negatively linearly related (P < 0.05) to water holding capacity and CL2 for steers on the CN diet. For steers on the CN diet, lightness (L*) values increased (P < 0.05) with increase in dopamine concentration. It was concluded that stress responsiveness and its relationship to certain beef quality attributes could be positively manipulated by supplementation with A. karroo leaves.

An experiment was carried out in which equal amounts of concentrate were given to beef cattle once, twice or three times per day, with a basal hay diet. There were no significant differences between treatments in food and water intake, digestibility coefficients, nitrogen balance data or live-weight gain.

The identification of individuals’ breed of origin has several practical applications in livestock and is useful in different biological contexts such as conservation genetics, breeding and authentication of animal products. In this paper, penalized multinomial regression was applied to identify the minimum number of single nucleotide polymorphisms (SNPs) from high-throughput genotyping data for individual assignment to dairy sheep breeds reared in Sicily. The combined use of penalized multinomial regression and stability selection reduced the number of SNPs required to 48. A final validation step on an independent population was carried out obtaining 100% correctly classified individuals. The results using independent analysis, such as admixture, Fst, principal component analysis and random forest, confirmed the ability of these methods in selecting distinctive markers. The identified SNPs may constitute a starting point for the development of a SNP based identification test as a tool for breed assignment and traceability of animal products.

Crossbred cows were evaluated for reproductive performance and live weight, and for pre-weaning growth and viability of progeny sired by seven unrelated breeds. They were also evaluated on overall productivity expressed as weight of weaned calf per cow mated per year, per 100 kg of cow per year and per 100 kg metabolic weight of cow per year. The cows comprised reciprocals of Africander with Mashona, Nkone, Brahman and Sussex, one-way crosses sired by Sussex out of Mashona, Nkone and Brahman dams, and by Charolais out of Africander, Mashona, Nkone, Brahman and Sussex dams. These represented sanga × sanga, sanga × zebu, Bos taurus × sanga, Bos taurus × zebu and Bos taurus × Bos taurus crossbred types. Bos taurus × zebu crosses were superior to other breed types for all the three productivity indices and for virtually all the individual components of these. There was little difference between the other four breed types in overall productivity of components of these. Differences between reciprocals were observed in sanga × sanga and sanga × zebu, cows with Africander dams being more productive than reciprocals with Mashona, Nkone and Brahman dams. The Bos taurus × Bos taurus cross was inferior in overall productivity primarily due to large cow weight and relatively low growth rate of progeny. Progeny sired by Friesian, Simmental and Brahman had higher weaning weights than those sired by Hereford, Aberdeen Angus, Africander and Tuli. Overall, heterosis was positive for all traits and averaged 0·15 for the three measures of cow productivity. Heterosis was three times higher in the Bos taurus × Bos indicus cross than in the Bos indicus crosses.

Vorderwald cattle are a regional cattle breed from the Black Forest in south western Germany. In recent decades, commercial breeds have been introgressed to upgrade the breed in performance traits. On one hand, native genetic diversity of the breed should be conserved. On the other hand, moderate rates of genetic gain are needed to satisfy breeders to keep the breed. These goals are antagonistic, since the native proportion of the gene pool is negatively correlated to performance traits and the carriers of introgressed alleles are less related to the population. Thus, a standard Optimum Contribution Selection (OCS) approach would lead to reinforced selection on migrant contributions (MC). Our objective was the development of strategies for practical implementation of an OCS approach to manage the MC and native genetic diversity of regional breeds. Additionally, we examined the organisational efforts and the financial impacts on the breeding scheme of Vorderwald cattle. We chose the advanced Optimum Contribution Selection (aOCS) to manage the breed in stochastic simulations based on real pedigree data. In addition to standard OCS approaches, aOCS facilitates the management of the MC and the rate of inbreeding at native alleles. We examined two aOCS strategies. Both strategies maximised genetic gain, while strategy (I) conserved the MC in the breeding population and strategy (II) reduced the MC at a predefined annual rate. These two approaches were combined with one of three flows of replacement of sires (FoR strategies). Additionally, we compared breeding costs to clarify about the financial impact of implementing aOCS in a young sire breeding scheme. According to our results, conserving the MC in the population led to significantly (P < 0.01) higher genetic gain (1.16 ± 0.13 points/year) than reducing the MC (0.88 ± 0.10 points/year). In simulation scenarios that conserved the MC, the final value of MC was 57.6% ± 0.004, while being constraint to 58.2%. However, reducing the MC is only partially feasible based on pedigree data. Additionally, this study proves that the classical rate of inbreeding can be managed by constraining only the rate of inbreeding at native alleles within the aOCS approach. The financial comparison of the different breeding schemes proved the feasibility of implementing aOCS in Vorderwald cattle. Implementing the modelled breeding scheme would reduce costs by 1.1% compared with the actual scheme. Reduced costs were underpinned by additional genetic gain in superior simulation scenarios compared to expected genetic gain in reality (+4.85%).

One hundred and fourteen castrated male cattle of various breeds were measured ultrasonically immediately prior to slaughter and the data were examined for correlations with the proportion of adipose tissue in the carcasses. Two flaw detectors and a simple scanner, the Scanogram, were used to make ultrasonic pulse-echo measurements of tissue thicknesses and areas. These were used to compute volumes of adipose tissue and muscle in a region of the back of each animal and the ratio of the volumes of the two tissues was examined for correlation with carcass fatness. Three individuals interpreted the Scanogram photographs and two made measurements using flaw detectors.

In general, pulse-echo measurements made by different individuals differed in magnitude and predictive value, even when identical scans were measured. Equally there were substantial differences between measurements when the same animals were measured by the same individual using different ultrasonic instruments.

In a parallel experiment, the speed of ultrasound transmission was measured at various locations on the living animal and the data were examined for correlations with carcass fatness. Unlike the pulse-echo technique, the transmission method was not prone to errors of subjective interpretation and did not require skill to interpret. Predictions based on speed measurements at two sites in the hind limb were as well related to carcass fatness as were those made on the basis of the best estimate of tissue volumes in the back. The use of two speed measurements in a multiple regression with the best Scanogram data significantly improved the accuracy of predictions of side fatness made on the basis of speed or pulseecho measurements alone.

Two types of analysis were used to examine the effectiveness of Ultrasonic selection of lean animals from a group of 50 Hereford castrated males of similar age and weight.

Decline in fertility of high-producing dairy cattle has become a global challenge to the dairy industry. Because of low heritability and complexity, it is difficult to find genetic markers for fertility traits in cattle. Here, we report the use of an in vitro fertilization (IVF) system and candidate gene approach to test genetic associations of a single-nucleotide polymorphism (SNP) in bovine placental lactogen (bPL), and its interactions with SNPs in the prolactin receptor (PRLR) and growth hormone receptor genes with fertility traits in an IVF system. The associations suggest a possible involvement of genetic interactions between bPL and PRLR in the fertilization and embryonic development processes, and the potential for application in a marker-assisted selection program.

1. Experiments have been performed to determine the thermal effects, on pigs, of the ingestion of whey at various temperatures while housed at various air temperatures.

2. Measurements of carotid artery and rectal temperatures showed that a general cooling of deep-body tissues occurred after the ingestion of cool whey.

3. Measurements of rectal and skin temperatures, and observations of respiratory rate and shivering activity, indicated that thermo-regulatory responses were induced by the ingestion of cool whey; the nature of the responses was dependent on the air temperature.

4. The results indicate that the temperature of liquid food offered to animals is a significant parameter in their climatic environment.

A series of experiments was conducted to examine the potential of using ammonia released from the hydrolysis of urea for alkali treatment of straw.

In an initial experiment (1) the effect on urea hydrolysis of adding either hydrochloric acid (HC1) or the surfactant alkyl phenyl ethylene oxide to straw of differing dry matter (DM) concentration was examined. The inclusion of HC1 or surfactant failed to improve the proportion of urea hydrolysed at straw DM concentrations of 450, 600 or 750 g/kg.

In experiment 2, straw was prepared and treated with urea, at a level of 20 (U2), 50 (U5), 70 (U7) g/kg straw DM and ammonia 40 (A4) g/kg straw DM to compare with untreated straw (S). Samples of the straws were milled and degradability at 60 h was estimated using the nylon bag technique. DM loss was significantly higher for all treated straws compared with untreated straw (P < 0·001). However, the proportion of added nitrogen retained from all urea treatments was less than 0·33 but U7 and U5 were approximately double that obtained from A4.

In experiment 3, 3-t batches of straw equivalent to treatments U2, U7, A4 and S were treated during September and later offered to steers in digestibility and food intake trials. Straws were ground through a 40-mm screen and offered to steers in digestibility stalls, in a balanced incomplete-block design. There were increases in the digestibility of DM (+0·08 g/kg), organic matter (+0·08 g/kg), and acid-detergent fibre (+0·09) of U7 and A4 straw compared with values for untreated straw (P < 0·01).

In a subsequent food intake trial treatment of long straw, with 20 g urea per kg straw DM (U2) failed to prevent moulding, however digestible organic matter intake (DOMI) of U7 and A4 straws increased by 0·42 and 0·27 kg/day respectively compared with intakes of untreated straw (P < 0·01). The application of 70 g urea per kg straw DM gave results comparable with treatment with 40 g ammonia per kg straw DM in improving digestibility of ground straw and the DOMI and preservation of long straw.

A simulation study, based on a closed sheepmeat breeding nucleus and incorporating marker-assisted selection (MAS), was used to evaluate response when different proportions of animals were marker typed. Two traits were included in the simulation: trait 1, a production trait where phenotypes were available prior to selection, and trait 2, a carcass trait where phenotypic information was not available on breeding animals. Selection on an index which comprised estimated breeding values (EBVs) for both traits was possible by calculating EBVs for trait 2 as the sum of EBVs for a polygenic component, obtained from a genetic regression, and EBVs for a major gene component, obtained by inferring genotypes at a major gene locus from a linked marker locus. Different marker typing strategies were evaluated. These differed in the criteria used to select progeny for typing, and in the proportion of male and female progeny selected. Typing progeny that were likely to be used as a breeding animal, but excluding those whose marker genotype could be predicted with reasonable certainty, was an efficient genotyping strategy. Close to maximum gain at the major gene locus was achieved when only a proportion of animals were marker typed (for example 90% of maximum response was achieved with a little over one-third of the selection candidates marker typed). This indicates the potential for substantial savings in relation to the cost of marker typing in commercial breeding flocks.

A feeding trial is described in which 32 individually-fed Large White pigs were used to investigate the effects of variations in the protein and energy status of the diet on growth, efficiency of food utilisation and carcass characteristics. The salient features of the finding were:

1. Over the weight interval 50–100 lb., it appeared that 1·0% was a more appropriate level of dietary lysine than one of the order of 0·75%; the former figure corresponded to a level of 5·8% of dietary protein.

2. In the ‘finishing phase’ of growth from 100–200 lb. the pig clearly tolerates wider energy : protein ratios than is the case in earlier life, with advantageous results in terms of growth performance but deleterious effects on carcass suitability.

3. An increase in dietary energy status in the ‘finishing phase’ yields growth responses only if protein level is appropriately adjusted.

4. It is suggested that Large White pigs require a level of 0·5–0·6% of dietary lysine in the ‘finishing’ period.

Rabbit lung is often used to study the pathophysiology of some congenital anomalies affecting the lung because its development is very comparable with that of human. Retinoids and the molecular transducers of the retinoic signal play a crucial role in mammalian lung development. In the rabbit, the molecular retinoic pathway has so far been poorly studied. As a first step in elucidating this process, we aimed to identify the retinoic acid receptors (RARs) and retinoid X receptors (RXRs). We cloned a part of the nuclear receptors (RARs and RXRs), and we used reverse transcription - polymerase chain reaction (RT-PCR) and immunohistochemistry assays to demonstrate the presence of RAR (α,β) and RXR (α, β) at all stages of rabbit lung development. Our results initiate further analysis into the molecular and genetic functions of retinoids during normal and pathological rabbit lung development including the surgical model of congenital diaphragmatic hernia.

Ninety-six multiparous sows were allocated at random on the 1st day of mating at the post-weaning oestrus to three dietary treatments of: 1·84 kg control diet (C); 0·92 kg control diet plus 0·92 kg pelleted hay (R); or 1·84 kg pelleted hay per day (M) for the following 10-day period to determine if restriction of nutrient intake affected reproductive performance. Subsequent to the 10-day period of nutrient intake restriction, all sows were fed 1·84 kg control diet once daily. The treatments had no effect on pregnancy rate, number of piglets born, number born alive, number weaned, or on piglet weight at birth or at weaning. Sows on the M treatment from oestrus to day 10 lost more weight (8·6 kg) during the 10-day period of nutrient restriction than the sows on the R (3·4 kg) or. the C (0·7 kg) treatments. However, weight gain from oestrus to day 110 of gestation was similar for all three treatments (16·5, 17·8 and 17·1 kg, respectively). Thus, restriction of nutrient intake early in pregnancy is not a critical factor affecting litter size and weight at birth or weaning in the multiparous sow.

The ability of the protein nutrition scheme proposed by the Agricultural Research Council (ARC, 1980, 1984) to predict responses to protein supply was examined in two experiments. In experiment 1, groups of nine British Friesian steers implanted with oestradiol-17β and nine non-implanted steers were fed from 133 to 300 kg live weight on each of four all-concentrate diets (metabolizable energy (ME) = 12 MJ/kg dry matter (DM)) containing ratios of soya-bean meal and formaldehyde-treated soya-bean meal such that undegradable protein (UDP) concentration was 19, 25, 32 or 42 g/kg DM. Rumen degradable protein (RDP) concentration was relatively constant (111 to 116 g/kg DM). Implantation did not affect DM intake (DMI, g/kg M0·75). Both live-weight gain (LWG) and food conversion efficiency (FCE) (LWG/DMI) were greater (P < 0·05) for the implanted cattle (LWG = 1·41 (s.e. 0·04) kg/day; FCE = 0·24 (s.e. 0·02)) than for the non-implanted cattle (LWG = 1·23 (s.e. 0·05) kg/day; FCE = 0·22 (s.e. 0·02)). There were no dietary effects on either DMI or FCE. In the non-implanted steers, UDP did not affect LWG but, for the implanted steers, there were positive, linear responses in LWG to both UDP concentration (P = 0·048) and UDP intake (P = 0·026). In experiment 2, groups of eight implanted steers were fed from 132 to 300 kg live weight on each of six diets (ME = 12 MJ/kg DM, soya-bean meal and formaldehyde-treated soya-bean meal as chief protein sources) supplying 17, 26, 34, 39, 54 and 82 g UDP per kg DM and concentrations of RDP up to 1·5 times ARC recommendations. There was no effect of UDP on either DMI or FCE but positive, linear responses in LWG to both UDP concentration (P = 0·019) and UDP intake (P = 0·010). In both experiments, mean DMI exceeded that predicted by ARC (1980) (P < 0·05). LWG predicted by the ME system and the ARC protein scheme was not significantly different from observed LWG for non-implanted steers, but was an underestimate of observed LWG for implanted steers (P = 0·002 in experiment 1, P < 0·001 in experiment 2). Observed responses in LWG to UDP concentration were also poorly predicted (regressions of observed on predicted LWG: experiment 1, r2 = 0·12, residual s.d. = 0·126; experiment 2, r2 = 0·004, residual s.d. = 0·119). It was concluded that oestradiol-17p has significant effects on responses in LWG to UDP, which are not predicted by the current ARC (1980, 1984) protein nutrition scheme.

1. 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-C14 acids and of palmitic acid per kg of milk yielded were greater than the intakes. The output of C18 acids 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-C14 acids and of palmitic acid and a decreased secretion of C18 acids 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.