The scientific and technological expansion of British agriculture between the mid 1930s and mid 1980s can be attributed primarily to the provision of favourable and stable prices and only secondly to government support of research and development. These conditions have changed. Most government-funded research in agriculture is now directed to the new biological sciences, molecular biology and transgenics. It is uncertain whether those at the frontiers of biotechnology are aware of the limits and constraints placed on animal production. Equally, it is uncertain whether the commercial supply services to agriculture will be prepared to meet the costs of transferring this new technology into production. These real problems facing agriculture are amenable to rational solutions. Of greater concern are food scares whipped up by pressure groups and government responses taken in the absence of, or in defiance of, scientific evidence.

Two examples are considered, one trivial, the other deadly serious. The first involves the recommendation that pregnant women ‘should not eat liver’ based on an unpublished report of a single case of birth defects. The second example chosen for discussion is the alleged causal relationship between the intake of saturated fatty acids (SFA) and coronary heart disease. The inadequacy of the simple distinction between saturated and unsaturated fats is briefly reviewed in the light of new knowledge relating to specific SFA, monounsaturates and the distinction between polyunsaturates of the linoleic and linolenic series. Evidence from large epidemiological studies is marshalled to demonstrate that there is no good case to support the conclusion of the Committee on Medical Aspects of Food Policy (COMA, 1984) that the nation's diet should be changed to reduce the proportion of saturated fats. The Department of Health is invited to recall COMA to reconsider their recommendations in the light of new evidence.

A herd of high-yielding Friesian dairy cows was observed outdoors and in a modern cubicle house. Indoors there was a much higher level of gross agonistic behaviour than at pasture (9·5 v. 1·1 per h). Furthermore, the use of continuous filming showed a high level of avoidance amongst the cows which impeded the movement of the more submissive cows. All cows spent proportionately 0·34 to 0·56 of their time indoors watching one another and 0·45 to 0·66 of their time in ‘social tension’. There was less synchrony of behaviour indoors than at pasture and despite the presence of one Calan Broadbent stall for each cow there was a high rate of displacement from the stalls involving cows of all degrees of dominance. The results are discussed in relation to housing design and husbandry practice.

The relation between survival to complete lactations 2, 3 and 4 and both linear type and production traits of pedigree Holstein-Friesian dairy cattle in the United Kingdom was analysed. There were records on 23 071 pedigree animals which were themselves type classified as heifers. The linear and quadratic phenotypic regressions of survival on most type traits were significant, even with yield fitted as a covariate. Phenotypic regressions of survival on milk, fat and protein yield were significantly positive, but that on protein content significantly negative. Phenotypic correlations with survival were under 0·1 for the linear traits, 0·16 for a subjective total type score, and 0·14 for milk yield. Genetic correlations between survival and type traits, estimated by multivariate restricted maximum likelihood, were as high as 0·4 for several traits of the udder and teats and for total score, and higher than for milk yield or composition. Regressions of survival on estimated sire transmitting abilities gave rather lower estimates of genetic correlations, except for total score. The results indicate that in these pedigree and classifying herds the total score is a culling criterion in its own right.

The relation between linear type traits and survival to complete lactations 2, 3 and 4 of pedigree and non-pedigree Holstein-Friesian dairy cattle in the United Kingdom was analysed. Regressions of survival on sire transmitting abilities for type, i.e. estimates of genetic regression, were obtained for different data sets, either pedigree or non-pedigree offspring of sires whose progeny had linear type assessments made by either the Holstein Friesian Society or the Milk Marketing Board, thereby spanning different segments of the cattle population. Results were not completely consistent either over lactations or over data sets. In general, however, there was a significant positive association between survival and angularity, fore udder attachment and udder depth scores, and a negative association with chest width, rump width, and teat length. Regressions on yield were positive, while those on fat and protein content were usually negative. Survival in the herd can be predicted, although not with high accuracy, using type traits.

Four Israeli-Friesian cows, two at peak and two at mid lactation, were fitted with duodenal cannulas. They were given proline or water infusions for 8-day periods to evaluate the effect of duodenal infusion of proline on arginine uptake by the mammary gland and on milk yield and composition of dairy cows. Milk fat content and 40 g/kg fat-corrected milk yield increased for all cows due to proline infusion. Milk protein concentration during either early or mid lactation and milk protein yield during early lactation, were not affected by proline infusion. Milk protein yield during mid lactation was increased due to proline infusion. Arginine uptake by the udder dropped by one-half during proline infusion. Results suggest that post-ruminal administration of supplemental proline reduced requirements for arginine by the udder and improved efficiency of dietary energy utilization.

During two experimental periods, eight non-lactating, rumen fistulated Simmental cows were given 2 kg/day of a cereal based concentrate and fescue hay ad libitum. The hay differed in neutral-detergent fibre concentration (LNDF: low; HNDF: high) and physical form (L: long; C: coarsely chopped). The rumen degradability of the dietary ingredients and of an extracted soya-bean meal was studied using the polyester-bag method.

The estimated effective rumen degradability <DG) of dry matter (DM) was significantly higher for LNDF than for HNDF hay (0·490 v. 0·401; P < 0·01). The DM DG of the extracted soya-bean meal and the dietary concentrate were higher when incubated with LNDF than with HNDF diets (0·630 v. 0·581, P < 0·05, and 0·541 v. 0·514, respectively).

Chopping the hay significantly increased the daily DM intake for HNDF diets (from 9·9 to 11·6 kg; P < 0·05), while no statistical differences were found between the other diets (10·2 and 9·6 kg, respectively for L-LNDF and C-LNDF diets). Cows given HNDF hay drank less water (42·4 v. 51·7 I/day) and total water consumption, expressed per unit of DM intake, was lower for the HNDF diets (4·1 v. 5·3 I/kg DM; P < 0·01).

Dietary treatments did not affect the estimated rumen turn-over rate of hay (0·027 per h on average, k1), hay post-rumen turn-over rate (0·069 per h on average, k2) or the estimated rumen liquid turn-over rate (0·100 per h on average, kj. The calculated outflow from the rumen was lower for the HNDF diets (159·4 v. 198·7 I/day). The daily amount of estimated saliva secreted did not differ between treatments, although saliva expressed per kg DM intake was significantly lower for the HNDF diets (10·8 v. 14·8 I/kg DM; P < 0·05).

The HNDF diets gave a lower post-feeding rumen pH (6·29 v. 6·58; P < 0·01), a higher concentration of n-butyrate (9·58 v. 8·32 mmol/l; P < 0·05) and a lower concentration of ammonia nitrogen (NH3-N) (80·5 v. 128·5 mg/l; P < 0·05). Of the C4 and C5 iso-acids, the rumen liquid from cows given HNDF diets had significantly lower concentrations of isobutyrate, isovalerate and n-valerate (P < 0·01). Hay physical form did not affect rumen pH, NH3-N and volatile fatty acid concentrations.

Two experiments were carried out with growing-fattening bulls, offered a fattening diet based on concentrate and supplemented with soya oil or steam-flaked linseed. Soya oil (200 g/kg) was mixed with middlings (800 g/kg). Linseed (500 g/kg) and whole barley (500 g/kg) were steam flaked. The fat incorporation resulted in an increase of the ether extract content from 26·5 g/kg dry matter to about 45 g/kg. The incorporation of soya oil increased the average daily gain (P > 0·05). The saturated: unsaturated fatty acid ratio was reduced in perirenal fat due to an increase of oleic acid and a reduction of stearic acid. The inclusion of steam-treated linseed resulted in a lower slaughter weight (P < 0·05) and a shorter fattening period (P > 0·05). The fatty acid composition of perirenal fat was affected significantly: the concentrations of oleic, linoleic and linolenic acid were increased and the concentrations of myristic, palmitic and stearic acids were reduced. This resulted in a reduced saturated: unsaturated fatty acid ratio.

In a third experiment, samples of the two fat concentrates were incubated in nylon bags in the rumen. The ether extract disappearance was high with both concentrates. Furthermore, the fatty acid composition was altered to a large extent for soya oil while large proportions of unsaturated fatty acids were still present with steam-flaked linseed.

A 2 × 2 × 2 factorial experiment was conducted with 128 growing-finishing steer calves to examine the effects of feeding whole v. rolled barley in diets containing either a constant proportion of concentrate (0·67) or proportionately 0·33 concentrate for 56 days followed by 0·90 concentrate for 83 days, with the concentrate being given at either 08.00 or 15.30 h. Steers given hay at 08.00 h and concentrate at 15.50 h grew proportionately 0·05 faster (P < 0-05) and had better dry matter (DM): gain ratios (P < 0·05) during the first 56 days than those given concentrate at 08.00 h and hay at 09.00 h. By the end of the trial steers fed at 15.50 h had similar daily gains to steers fed at 08.00 h but required proportionately 0·02 less DM: gain (P <0·05). No significant difference in gain was detected between steers given whole (1·30 kg/day) or rolled (1·38 kg/day) barley, but those given whole barley ate proportionately 0-08 more DM daily and had a proportionately 0-15 poorer DM: gain ratio (P < 0-05). The digestibility of diets containing whole grain was reduced (P < 0-05). Thirty-six steers given whole barley bloated compared with nine given rolled barley (P < 0·05). No significant differences were found either in DM intake or in final proportion of concentrate in the diet between steers given the diet containing proportionately 0·67 concentrate throughout the feeding period and those given the variable concentrate diets. There was a trend for DM: gain ratios to be poorer for steers given the constant proportion of concentrate (6·89 v. 6·65).

The effect of insulated (IN) and uninsulated (UN) buildings on food intake, performance and body temperature of sheep was studied over 4 years. The lowest average monthly temperature was -13·1°C. In the UN the temperature was on average 6-6°C higher than outside but the temperature in the IN remained fairly constant and was close to 10°C. Summarized for all 4 years the roughage intake was proportionately 0·02 higher in the UN than in IN (P > 0·05). There was no effect of treatment on weight gain, but the weight of the fleece was higher in IN than in UN (1·74 kg v. 1·66 kg per sheep). The mean age at first oestrus was 222 days. There was no difference in the length of pregnancy and lambing percentage was 185% in both treatments. The average birth weight was higher for lambs born in UN than IN (5·10 v. 4·95 kg), but the weight at weaning was the same. On only one occasion was the rectal temperature lower for ewes in UN than IN before shearing (38·7°C v. 39·2°C). After shearing no effect of treatment was found except for the 1st year, but in year 2 there was an interaction between plane of nutrition and housing. Results clearly indicated that uninsulated buildings are well suited for sheep.

The production responses of crossbred lambs [Poll Dorset (♂ × (Border Leicester ♂ × Merino ♀)] immunized against somatostatin (sornatotropin release inhibiting factor; SRIF) and whose mothers were also given anti-somatostatin vaccination was investigated in this study. There were no significant differences between immunized and control lambs in term of live-weight gain, food intake, food conversion efficiency, digestibility, eating pattern, wool growth and carcass composition. The concentration of growth hormone in plasma of immune lambs was not significantly elevated, even though the lambs had a generally increasing anti-SRIF antibody titre during the experiment. The findings suggest that although the lambs were successfully immunized against SRIF, homeorhetic mechanisms maintained growth hormone and productivity traits within normal levels.

Commercial carcass grading measurements and sample joint dissection were evaluated as predictors of carcass lean concentration using a data set of 1320 pig carcasses from four breeding companies. Entire males, castrated males and gilts from White-type and Meat-type populations were reared on ad libitum or restricted feeding regimens and slaughtered to achieve a carcass weight of either 52·5 kg or 72·5 kg. A model was fitted which examined the accuracy and stability of regression equations for different populations, sexes and feeding regimens, and different values of P2 and carcass weight. The regression slope of lean concentration on P2 differed by sex and population. Lean concentration decreased faster with increases in P2 among gilts than among entire or castrated males. At the same level of P2 and carcass weight, pigs fed ad libitum contained 5 g/kg less lean in the carcass than pigs fed at a restricted level. Biases among populations, sexes and feeding regimens were also found when carcass lean concentration was predicted from additional measurements: muscle depth at P2, fat thickness and muscle depth at 3/4 last ribs, and eye-muscle area. The regression slope of lean concentration on sample joints showed little evidence of variation among populations (except for the hand joint), sexes or feeding regimens. There were important differences in the intercept for different populations. The ham was the most accurate (residual s.d. = 11 g/kg) and least biased joint.

By a combination of complete and incomplete dissections a considerable increase of precision or reduction of expense may be obtained in the construction of a prediction formula for the proportion of lean meat of a carcass from objective carcass measurements. This approach, referred to as double-regression, is demonstrated on data involving dissection of pig carcasses in The Netherlands. Advantages of double-regression relative to ordinary regression with respect to precision and experimental cost are discussed. Expressions for optimal sample sizes at fixed total cost are derived.

Effects of creep food presentation on feeding behaviour and intake were studied with eight litters of eight to 10 Yorkshire × Landrace piglets in the 3rd and 4th weeks after birth, before weaning at 4 weeks of age. In each week, four treatments were applied, each for 24 h: a single two-space feeder unchanged from the previous day; a clean feeder with fresh food supplied at 09.00 h; a clean feeder with fresh food supplied at three times during the day; and three feeders (six feeding spaces) providing increased access to food throughout the day. There were no significant differences between the first three treatments in time spent at the feeder (recorded by video over 24 h) or food intake of piglets. However, the fourth treatment increased average intake in week 3 to 2·1 times the average of the other treatments, and in week four to 1·4 times. In week 3, most piglets spent more time at the feeder when access was increased, while in week 4 the effect was restricted to piglets which ate very little. This suggested that imitative learning was important in the initiation of feeding. Analysis of both litter means and within-Utter variation showed that piglets which ate more solid food before weaning gained more weight in the 2 weeks after weaning. However, this correlation was confounded by correlations of both measures with birth weight and other variables. Causal links between creep feeding and post-weaning weight gain remain to be demonstrated.

In most regions of the world, condemnations of porcine livers are almost always due to parasitic Ascaris suum infections. Thus, accurate data for all abattoirs in a region will reflect the prevalence of this disease in the pig population of that region. In Northern Ireland, a computerized information database retrieval system for abattoir data has been available since 1986. The information recorded by the system details the specific cause and location of all condemnations in cattle, sheep and pigs for all abattoirs in Northern Ireland since 1969. In this paper, results of analysis of a subset of these data (1969 to 1989) for pigs is presented and a univariate time series model identified for the recorded prevalence of condemnations due to cirrhotic lesions in pig livers. The results of the analysis demonstrate a very highly significant upward trend in the occurrence of Ascaris suum infections. The residual terms for the model were correlated with the corresponding time series of all the key meteorological variables. The association between the level of lesions and the mean level of air temperature over the early summer period is highlighted. The overall proportion of variation accounted for in the time series of the annual level of cirrhotic condemnations was 96%.

Pigs were fed either ad libitum or given 300 g/day of the same food (digestible energy 15·4M)/kg; crude protein 208 g/kg fresh food) from 6 to 12 kg live weight (LW). Four pigs were killed at 6 kg LWand eight (equal numbers from the two sexes) from each treatment at 12 kg LW. Eight pigs (three males and five females; AL) were continued on ad libitum feeding to 24 kg LW when they were killed. Ten (four males and six females; R) of the pigs which had been restricted to 12 kg LW, were fed ad libitum to 24 kg LW, when they were killed. The entire empty bodies of the pigs killed were chemically analysed and the weights of organs determined. The empty body was considered as three fractions: the entire skin, including the subcutaneous fat (SK); the internal organs and the empty gastrointestinal tract (INT) and the remainder (CARC). The distributions of the chemical components between these three fractions were determined.

The R pigs took 19 days longer and 2·6 kg more food to go from 6 to 12 kg LW. At 12 kg LWthey had less gut fill, lighter organs concerned with food processing and less lipid, more protein and heavier CARC weights than the AL pigs. The R pigs took 5·5 days less and 2·4 kg less food to go from 12 to 24 kg than the AL pigs. At 24 kg LW they had more gut fill, similar weights of the organs concerned with food processing, and slightly less lipid and protein. Over the 12 to 24 kg weight interval the R pigs gained lipid and protein at faster rates than the AL pigs. None of the increase in protein growth rate was in the CARC fraction.

It is concluded that pigs given a low intake of food adjust their organ weights to be sufficient to process the allowance. On being given ad libitum food they rapidly increase the weights of their organs to process the increased rate of intake, and increase their gut fill. These effects are seen as a short lived, greatly increased rate of LW gain. During rehabilitation lipid stores return to their normal level but carcass protein does not show an increased rate of growth.

The effects of dietary sucrose, glucose and starch were compared to determine whether sucrose as an energy source affected energy or protein metabolism of growing pigs given food either frequently or once daily. Three experiments were conducted using three diets (0·8 g lysine per MJ digestible energy (DE)) containing sucrose, starch or glucose, respectively. In the first experiment, the DE contents of the diets were determined. In the second, the diets were given either once daily (08.00 h) or frequently (3-h intervals) to growing pigs (20 to 45 kg live weight) and growth responses, blood characteristics and energy, protein and fat retention measured. In the third experiment, the three diets were given to seven pigs (50 kg live weight), either once daily or frequently to monitor further the effects on plasma triglycerides, glucose, urea and insulin levels.

Growth rate, on a carcass basis, was slightly lower in pigs given glucose relative to starch (P < 0·05) but there was no effect of carbohydrate source on the retention of energy, protein or fat. Plasma triglyceride levels were lower in pigs given starch (P < 0·05) whilst plasma glucose and insulin concentrations were higher immediately after feeding in pigs given food once daily (7 < 0·05, P < 0·01). All three carbohydrate sources were used less efficiently by the pigs for energy, protein and fat deposition with once daily compared with frequent feeding (V < 0·01). Overall, these results indicate that sucrose as an energy source does not effect energy or protein metabolism by the growing pig. It appears that the metabolism of fructose within sucrose had no effect on metabolism.

Despite much discussion on the use of simple profit equations to estimate economic weights, no study appears to have tested the accuracy of this method. This paper carries out such a test from the viewpoint of the individual farmer by comparing economic weights calculated in the normal way with results gained from a more empirically acceptable, non-linear equation. Although the study concludes that simple profit equations are likely to be sufficiently accurate in most circumstances, further consideration needs to be given to a series of time periods and the industry and economy at large.

A method was suggested that attempts to distinguish between the underlying lactation curve, the effect of season of production, and the effect of time after conception. The composite function was shown to give a better fit than an incomplete gamma function. The estimated parameters of the underlying lactation curve were unaffected by season of calving whereas the parameters of the gamma function were not. Pregnancy started to affect yield 160 days after conception by -0·1 kg/day. The difference between the best season of production (May) and the worst (November) was around 5 kg.

Simulation results of closed MOET schemes have evidenced several problems issuing from selection in small populations using family information and diverse modifications of the original schemes have been proposed. Mate selection, based on linear programming techniques, includes most of the desirable properties of other methods and offers additional advantages. Some applications of this technique to improve the results of dairy cattle MOET schemes with hierarchical and factorial mating systems have been analysed in this note by computer simulation. Other applications of the method are also discussed.

The attainment of puberty in September-born early-maturing ewe lambs was studied at Zaragoza (latitude 41° 40' N). Thirty twin Salz females were allocated to two groups receiving two nutrition levels after 3 months of age: high (500 g/day lucerne hay and 500 g/day concentrate) (H) and low (500 g/ day lucerne hay) (L). Oestrus was detected daily by aproned rams. Corpora lutea were counted after oestrus and plasma progesterone levels monitored each week.

In the first breeding season (January to February) the percentage of females showing sexual activity (silent emulation or oestrus and ovulation) was higher in the H compared with the L group (67 and 20%; P < 0/05). Nonpubertal oestrus before the main breeding season was detected in 67% of animals. In the main breeding season and for H and L groups respectively, percentage of females showing silent ovulation before puberty was 67 and 33% and mean age at puberty extended to 319 (s.e. 4-8) and 314 (s.e. 3·7) days. Ovulation rate at puberty was 1·73 (s.e. 0·13) and 1·33 (s.e. 0·15) respectively (P < 0·05).