In a study involving 240 pigs, starter and grower diets containing copper at a high level (180 mg/kg) or olaquindox (110 mg/kg and 50 mg/kg in starter and grower diets respectively) or both were compared with a control diet containing 15 mg Cu per kg. The pigs were weaned at 21 days and given the starter diets until they reached a mean live weight of 10·2 kg, followed by grower diets for 28 days.

In both the starter and grower periods, the effects of the high Cu supplement were not significant. In the starter period, olaquindox significantly improved daily gain (by 25 g) and food conversion efficiency proportionately by 0·07 (P < 0·01). In the grower period, olaquindox did not significantly affect performance.

1. Short cold exposures (2 hr at 18° or 8°C) were used to delay or block panting during subsequent heat stress in shorn Merino and Scottish Blackface sheep. The effect of previous acclimatization to cold upon the block to thermal panting was studied.

2. After acclimatization the block was reduced, but less in Merinos than in Blackfaces. In Blackfaces, the reduction effect was inconsistent after short periods of acclimatization, but became significant after prolonged (3 weeks) acclimatization.

3. Acclimatization produced elevations in heart rate and body temperature implying increased heat production. Variation in block reduction between breeds and between individuals was related to these presumed changes in heat production. Sheep with highly elevated metabolic rates showed complete block prevention. 4. After cold exposure ceased, elevated heat production disappeared within 8 days and the block returned.

5. It was concluded that elevated heat production resulting from acclimatization caused block prevention partly because increased heat storage cancelled the heat debt otherwise incurred during blocking treatment and partly because the increased requirement for heat dissipation overruled the respiratory centre block.

Water consumption has been considered to be a function of dry-matter (DM) intake (Leitch and Thomson, 1944; Winchester and Morris, 1956). Thus, water requirement for ruminants has been presented as kg per unit of DM intake (Agricultural Research Council (ARC), 1965; Japanese Agricultural and Fishery Technology Council, 1974). Little work, however, has been done on the effect of the DM concentration of a diet on water consumption in cattle.

A large variety of processes - physical, chemical and/or biotechnological - is currently applied to cereals (Table 1).

Among physical treatments, grinding is the most comnon ; it does not modify the chemical characteristics of the grains but improves the accessibility of the enzymes of the gut to their substrates by disrupting endosperm and aleuron cell walls. Thus, milling exposes the interior parts of the grain to the digestive enzymes. Some physical processing of barley grain, such as rolling, is necessary to give optimum digestion of the nutrients by cattle (ORSKOV, 1976). This treatment, applied to barley, appears to be beneficial for young species (KREFT and BOYLES, 1989). Pigs eat whole or very coarsely milled grain reluctantly (MAXWELL et al., 1970) and utilize whole barley poorly (LAWRENCE, 1970). For this reason, barley grain is commonly milled before feeding. Grinding of maize using a roller mill does not modify average daily gain, feed intake, feed conversion and fattening time of pigs. However, sensory evaluation tests, meat from control pigs fed untreated maize is preferred to meat from pigs given rolled maize (ITOH et al., 1986). However, finely ground barley causes a strong increase in the frequency of oesophagogastric lesions whereas diets countaining coarsely ground barley or crushed oats caused few lesions. Balance trials on lamb indicate that whole maize have more digestible, metabolizable and net energy than ground maize (BONSEMBIANTEE et al., 1988).

There are two schools of thought concerning the most appropriate environment in which to select breeding animals. One says ‘ Always select animals under environmental conditions similar to those where they are to be used ‘. The other says ‘ Select breeding animals in the optimum environment so that they have the best chance of revealing their genetic capabilities ‘. Experiments on growth of laboratory mice and experience with European cattle in the tropics have shown the advisability of the first course in these cases. In regard to hill sheep and dairy cattle in Britain, on the other hand, practice favours the second course, but there is little experimental evidence to support it.

In an integrated group housing system for sows, animals of all stages of production are kept in one group, except around farrowing, and remain there throughout their productive life. Lactating sows have access to the suckling section of the house via an electronic gate. Jostling of piglets from different litters is avoided by keeping the litters in their own suckling pen until weaning. The system allows lactating sows to freely evade their piglets, and move between the suckling section and the communal area. They can maintain their social position and cool off in the relative cool communal area. Earlier observations (Houwers et al., 1992) showed sows decreased sucklings and increased their absence from the farrowing pen towards weaning. It was not clear whether the overall performance of the piglets was depressed by absence of sows before weaning. The relevance for practical farming partly depends on the production results that can be achieved.

A general parabola constrained to pass through points (0,0) and (1,1) yields a linear one parameter (q) function which can be used to relate the fraction of maturity of organs or masses of tissue to the fraction of maturity of the whole animal. This is an empirical approach. It is often preferable to derive a function from a theory of the phenomenon under study. A theory of feeding and growth of animals is used to derive a non-linear one parameter (k) function which can be used to study the same data to which the linear q-function is applicable. The parameter, k is directly proportional to the fraction of total nutrients consumed by the animal which is allocated to the organ as the animal ages. If the fraction of nutrient allocated remains constant, the parameter k is constant and has the same properties as the parameter q. However there is nothing in the theory which constrains k to be constant, therefore, the q-function is of more general use than the q-function in the study of the relationship of the fraction of maturity of organs to that of the whole animal. Two cases are presented to illustrate this generality.

The effects of altering the glucogenic potential of the diet of wether lambs (initial body weight 56·4 kg) offered an energy allowance of 0·25 that required for maintenance on body-weight loss, nitrogen retention and blood and rumen fluid parameters were examined. Whole barley was offered alone or substituted on an isoenergetic basis with 40 or 120 g of a blend of glucose precursors (polyhydric alcohols, propylene glycol, sodium propionate) absorbed on to palm kernel meal (acetona meal), to 36 lambs (no. = 12 per treatment) for 8 weeks. Substituting barley with 40 g acetona meal had a small but non-significant effect in decreasing body-weight loss and plasma aspartate amino transferase activity and in increasing plasma insulin concentration. Increasing the glucogenic potential of the diet by substituting barley with 120 g acetona meal decreased body-weight loss in the early phase of the study, decreased plasma concentrations of non-esterified fatty acids and increased the proportion of propionate in volatile fatty acids in rumen fluid, plasma aspartate amino transferase and gamma-glutamyl transferase activities and plasma insulin concentrations. Increasing the glucogenic potential of the diet did not affect nitrogen retention or plasma glucose concentration. It is concluded that increasing the glucogenic potential of the diet of lambs resulted in an increase in metabolic efficiency at the onset of negative energy balance which was mediated through a change in plasma insulin concentration. The absence of a significant difference in body-weight loss between the diets in the latter part of the study reflects the lack of sustained ketosis.

Malt distillers grains (MDG) and brewers grains (BG) are the fibrous residues remaining after the extraction of sugars from malted barley during the process of malt whisky and beer production, respectively. MDG and BG are popular supplements in beef finishing diets with up to 15kg/head/day being fed on Scottish farms (Lilwall, Smith and Wood, 1983). However, in some areas, close to distilleries and breweries, and particularly during the summer months, MDG and BG can be bought cheaply and ensiled, and could be fed to appetite as the sole or major part of the diet. This investigation explores this possibility.

Some unusual limitations of MDG and BG as a complete diet are that they are virtually devoid of soluble minerals such as Na and K and are low in some trace elements and vitamins. They also contain high levels of unsaturated fats which depress fibre digestion and voluntary dry matter intake (Miller et al., 1970). This effect can be partly overcome by supplementation with calcium carbonate (El Hag et al., 1972) probably by the formation of insoluble calcium soaps of fatty acids in the rumen. Based on these considerations a mineral/vitamin mix was designed specifically to supplement these materials.

Silage fermentation is progressively restricted as the extent of pre-wilting increases (O'Kiely et_al., 1988). The magnitude of the improvement in silage nutritive value in response to a lactic acid bacteria inoculant could be related to the extent of the fermentation in the untreated silage. The objective of this experiment was to determine if the response in silage nutritive value to a Lactobacillus plantarum inoculant was similar at different levels of dry matter (DM) concentration.

In four experiments, 189 gilts either received PMSG antiserum around the time of a PMSG- (experiments 1, 2 and 3) or PMSG/hCG-induced (experiment 4) oestrus or served as controls. Ovulation rates were not affected by treatment. There was no treatment effect on pregnancy rate (experiments 2, 3 and 4). In experiment 2, numbers of embryos in PMSG-treated control gilts were quite low and were higher (P < 0·05) in those gilts subsequently receiving anti-PMSG treatment. In experiment 3, the mean number of embryos in control gilts were higher than in experiment 2 and there was no effect of immunoneutralization of PMSG. No treatment effect was evident in PMSG/hCG treated gilts (experiment 4). These data indicate that the immunoneutralization of PMSG is unlikely to improve the reproductive performance of gilts following a gonadotropin-induced oestrus except in gilts that otherwise would have poor performance.

Sows kept outdoors are traditionally fed a compound diet, in the form of a-large biscuit, which is spread on the ground over a wide area to try to minimise bullying. They can be kept in several separate groups, divided by electric fencing, each group containing sows at a similar stage of pregnancy. The use of a computer controlled feeder would allow the sows to be kept as one dynamic group and allow food intake to be controlled on an individual or group basis. Also, normal pelleted food can be used in such a machine. Bulky feeds are playing an increasing role in the diet of outdoor sows, and it was decided to investigate the use of an electronically controlled feeder to supply a compound feed to balance grazed fodder beet.

This study was carried out on Bauscat (B), New Zealand (N), Californian (C), N × C (NC) and B × NC (BNC) rabbits. Overall reproductive performance for does with premature parturition (pre-term) of the five breeds was determined and compared with that of does delivering at the normal time (full-term). Full-term does showed a reproductive performance superior to that of pre-term does in all five breeds with larger litter size at weaning, more pups weaned per doe and a lower proportion of stillbirths. Pre-term B, N and BNC does had a larger number of pups weaned than pre-term C and NC does (P < 0·01). There was a high incidence of pup mortality in premature litters, and the main causes of this high mortality were respiratory distress syndrome, crushing of the skull and starvation and chilling.

The mean serum oestradiol 17-β concentrations and degrees of cervical mucous ferning in pre-term B does were higher than in full-term does (P < 0·01) but the mean serum progesterone concentrations in pre-term B does were lower than in full-term does during the gestation period (P < 0·01). Treatment with either dexamethasone or progestin reduced pup mortality in pre-term does and the birth-to-remating interval was shorter in pre-term does treated with dexamethasone (P < 0·01) but longer when treated with progestin (P < 0·01).

This study was performed to assess the relationship between serum growth hormone (GH) and insulin-like growth factor 1 (IGF-1) levels, slaughter weight, and myogenic satellite cell growth kinetics of Targhee rams. Serum was collected from 19 rams at 15-min intervals over a period of 4h. Radioimmunoassays of serum samples for GH revealed considerable variation (within individual rams) over the sampling period, with mean values ranging from 0·63 to 4·88 μg/l (mean overall 2·3 (s.e. 0·33) μg/l; no. = 19). There was no significant correlation between GH levels and slaughter weight (r = −0·11; P > 0·05) at 155 (s.e. 1·08) days. Serum IGF-1 levels of (individual) rams were invariant over the sampling period, with individual means ranging from 62 to 233 μg/l (mean overall of 117 (s.e. 45·6) ugll; no. = 19). IGF-1 was not strongly correlated with slaughter weight (r = +0·35; P > 0·05). Satellite cells were isolated from the left m. semimembranosus of all rams at slaughter and grown in culture to evaluate proliferation amount and differentiation extent. The correlations between serum GH levels and satellite cell proliferation and differentiation in vitro were r = −0·53 (P < 0·05) and r = −0·52 (P < 0·05), respectively. Serum IGF-1 showed no significant correlations to proliferation (r = +0·07; P > 0·05) or to differentiation (r = −0·07; P > 0·05) of the satellite cells. These data suggest that serum GH levels in Targhee rams may not reflect muscle growth potential if correlated to body weight of 155 days. Furthermore, as IGF-1 was not correlated significantly with slaughter weight or to variables of satellite cell proliferation and differentiation, another mode of satellite cell regulation (possibly paracrine controllers) is more likely at play to coordinate the satellite cell involvement in muscle growth in Targhee rams at 155 days.

The relationships between some wool characteristics and blood group genotypes (AaAa, AbAb, AaAC, AAb, AC and AbAc) were studied in Ossimi and Rahmani Egyptian fat-tailed breeds of sheep.

Interrupted medullation and coarse wool percentages and grade of wool were significantly related to blood group genotypes (P < 0·01). Fibre length and diameter and continuous medullation percentage were significantly related to genotype (P < 0·05). Staple length, number of crimps per cm, percentages of kemp, clean wool, impurities, moisture regain and fine wool were not significantly related to blood group genotype (P > 0·05).

Feed barriers and mangers form an integral part of a cattle housing system. Their role is to prevent the animals’ wasting feed by scattering it or by walking and defecating over it. Feed barriers generally effect a better distribution of feed and should allow individuals adequate and ready access. Often they have a dual role and act as the side of a pen. These functions are often achieved with some regard to several managerial objectives; simplicity of feed distribution, labour economy, the regulation of excessive animal activity, minimal feed wastage and promotion of animal comfort.

Time spent at the feed barrier depends on the feedstuff, the rate of eating by the animal, space allocation, and the accessibility of the feed. Depending on the feed barrier design the animal may need to exert some force to reach the food. Injuries arise in those situations where large forces are exerted against the barrier and/or accommodating postures (ie kneeling or other) are adopted to reach the food. In extreme cases intake may be restricted. Thus, to assure maximum intake and minimise injuries the feed must be within the easy reach of the animal. Two trials with Friesian heifers compared the performance of 4 types of feed barrier.

The assessment of herbage intake using the n-alkane technique requires estimates of the n-alkane concentrations in the diet. The objective of the present study was a) to assess the magnitude of sampling variation in n-alkane concentrations among herbage samples taken from individual oesophageal fistulated wethers, b) compare n-alkane concentrations determined from oesophageal extrusa, hand plucked, and mechanically clipped herbage samples and c) assess the effect of errors in the estimates of herbage n-alkane concentrations on the accuracy of intake estimates.