Heat production, energy and nitrogen balances of artificially reared piglets from specific pathogen free sows, housed in a respiratory chamber, were measured over five successive periods of 7 days each from 4 to 39 days of age. The experiment was carried out at an environmental temperature decreasing from 33 to 27°C. The mean weight increased from 1·5 (at day 4) to 11·9 kg (at day 39). Daily rate of gain increased from about 100 g in periods 1 and 2 to 502 g per piglet in the fifth period.

Daily protein deposition, as measured via nitrogen balance, increased from 17 to 96 g; fat deposition increased from about 0 to 100 g. Body composition at the start and end was determined by a comparative slaughter technique. Protein and fat content had a high correlation coefficient with body weight (R2 = 0·69 and 0·89, respectively). At birth these values were much lower, 0·24 and 0·01 for protein and fat, respectively.

Nitrogen balance compared with slaughter technique led to an overestimation for protein deposition of proportionately 0·07. Fat gain measured from slaughter was proportionately 0·08 lower than that calculated from energy balance.

Ratio of gain estimated from protein and fat gain with the balance technique relative to that measured ranged between 0·93 to 1·15 in various periods.

The effects of culling, natural wastage and different correction and exclusion procedures on estimates of lactation parameters have been examined in test station records of 1042 Danish Red cows. A total culling rate of 20% was applied to the initial material, of which 11% represented obligatory culling for disease, injury and infertility and 9% ‘paper’ culling for performance at four different stages of lactation.

Exclusion and correction of short records generally resulted in overestimates of the sample mean and underestimates of the selection differential produced by culling. In all instances, the variance of the sample prior to culling, and the loss of variance attributable to culling, was underestimated in samples containing short or corrected records.

It was concluded that field data cannot provide material suitable for objective studies of selection and that a reappraisal of the effects of age, lactation, season, etc., in the controlled conditions of test stations may well be justified. An absence of culling in test stations contributes to the large estimates of variance and heritability characteristic of station material.

Milk protein genes are among the most intensively expressed and they are active only in epithelial mammary cells of lactating animals. They code for proteins which represent 30% of the proteins consumed by humans in developed countries. Mammary gland development occurs essentially during each pregnancy. This offers experimenters attractive models to study the expression mechanisms of genes controlled by known hormones and factors (prolactin, glucocorticoids, progesterone, insulin-like growth factor-1 and others) as well as extracellular matrix. In the mid-1970s, it became possible to identify and quantify mRNAs from higher living organisms using translation in reticulocyte lysate. A few years later, the use of radioactive cDNAs as probes made it possible for the quantification of mRNA in various physiological situations using hybridisation in the liquid phase. Gene cloning offered additional tools to measure milk protein mRNAs and also to identify transcription factors. Gene transfer in cultured mammary cells and in animals contributed greatly to these studies. It is now well established that most if not all genes of higher eukaryotes are under the control of multiple distal regulatory elements and that local modifications of the chromatin structure play an essential role in the mechanisms of differentiation from embryos to adults. The technique, known as ChIP (chromatin immunoprecipitation), is being implemented to identify the factors that modify chromatin structure at the milk protein gene level during embryo development, mammogenesis and lactogenesis, including the action of hormones and extracellular matrix. Transgenesis is not just a tool to study gene regulation and function, it is also currently used for various biotechnological applications including the preparation of pharmaceutical proteins in milk. This implies the design of efficient vectors capable of directing the secretion of recombinant proteins in milk at a high concentration. Milk protein gene promoters and long genomic-DNA fragments containing essentially all the regulatory elements of milk protein genes are used to optimise recombinant protein production in milk.

Sales of semi-skimmed milk in the USA and in many European countries are increasing, while those of whole milk are decreasing. Although consumption of whole milk in the U.K. is much higher than in other EC countries, sales have been declining in recent years. The amount of semi-skimmed milk sold in the U.K. is very small and in many parts of the country can only be obtained with difficulty. The object of this paper Is to compare changes in demands for liquid milk in the U.K. with those of other countries in an attempt to understand the relationship between the market for semi-skimmed milk and for whole milk.

1. 768 lambs on fourteen farms in the north-east of Scotland were divided into a control group and groups receiving two 5 mg., three 5 mg., two 7·5 mg., and one 15 mg. pellet of hexoestrol.

2. On every farm the mean rate of live-weight gain of the treated lambs was greater than that of the controls.

3. There appeared to be very little difference between implantations of two 5 mg., three 5 mg. and two 7·5 mg. pellets of hexoestrol but on four farms where a direct comparison was made one 15 mg. pellet was slightly inferior to three 5 mg. pellets.

Fifty-six Landrace ♂ x Yorkshire ♀ gilts were divided at 140 days of age into four groups in a 2 x 2 factorial design whereby they were exposed continually (BE) or not exposed (NE) to a mature boar and were or were not blood sampled twice weekly for progesterone determinations.

There was no effect of BE on the age at the first or second ovulation. Since detection of oestrus was only 70·80% accurate, BE apparently delayed the onset of first and second oestrus by 16 days (p = 0·06). Blood sampling advanced first oestrus by 15 days (F = 0·07) and second oestrus by 32 days (P = 0·001).

The results suggest that gilts are unlikely to be responsive to boar exposure at 140 days of age, that observations of oestrus alone may be a misleading end-point of the effect of boar exposure and that the use of blood sampling for the measurement of progesterone as an index of ovarian activity may attenuate the response to stimuli intended to advance puberty in the gilt.

The female progeny of Angus, Boran and Red Poll bulls mated to Ankole, Boran and Zebu cows were compared. Heifers by Angus and Red Poll sires out of Boran and Zebu cows could be mated at an average age of 23 months with excellent calving percentages, whereas Boran-sired heifers and heifers from Ankole cows were not ready for service at this age. Lactation stress caused heifers suckling calves to lose 4% of body weight over a 7½ month suckling period, while heifers not suckling calves gained 14% in body weight. Heifers by Red Poll sires did not provide more milk for their calves, as measured by early growth rate, than heifers by Angus or Boran sires. The effect of hybrid vigour on mothering ability of F1 dams was at least as great as it was on the early growth of the F1 crossbreds themselves.

Three changeover experiments, each with 16 milking cows, were conducted to evaluate the effects of stage of growth of lucerne, level of feeding of lucerne or ryegrass and level of inclusion of barley. The artificially dried and processed forages were in the form of cobs and given to cows in addition to a basal ration of hay. Late-cut lucerne (organic matter digestibility, OMD, 55%) promoted significantly lower milk yields than early-cut lucerne (68% OMD). When offered ad libitum in two meals each day both forages were eaten in quantities of about 13 kg dry matter. Ryegrass cobs (79% OMD) produced more milk than lucerne cobs (59% OMD) but gave similar milk yields per unit of digestible organic matter. Production rations supplying similar amounts of digestible organic matter and composed of different proportions of lucerne cobs and rolled barley gave similar milk yields. It is concluded that the relative milk-producing value of processed forages depends on their content of digestible organic matter. However, their bulk may limit their value and the inclusion of cereal with the dried forage may be worth while.

A total of 276 crossbred pigs were used in three trials to determine if feeding spray-dried animal plasma (SDAP) in simple phase 1 piglet diets with differing soya-bean meal (SBM) levels can influence performance or immunoglobulin G (IgG) levels specific to the antigenic soya proteins, glycinin and β-conglycinin. Pigs were blocked according to initial body weight and equalized across treatments according to gender and ancestry. Blocks of pigs were then randomly assigned to one of three treatments in a completely randomized block design. The dietary treatments were as follows: (1) 10% +: 100 g/kg SBM with 75 g/kg SDAP; (2) 20% +: 200 g/kg SBM with 75 g/ kg SDAP; (3) 20%-: 200 g/kg SBM without SDAP. Pigs were given treatment diets for 14 days, followed by a common diet for the duration of the trials (35 days). Average daily gain (ADG) and gain to food (G: F) ratios were not affected by dietary treatments. Average daily food intake (ADFI), however, was greater for pigs given 10% + as compared with 20% + and 20%- (P < 0.05) during days 0 to 14 post weaning. Addition of SDAP increased ADFI (P < 0.01) and tended to increase ADFI when added to diets containing 200 g/kg of soya-bean meal (P = 0.06). No differences were detected in soya-specific IgG levels during any collection period. These data suggest that SDAP addition to simple phase 1 piglet diets increased ADFI during the first 2 weeks, but did not alter ADG or food efficiency. There was no indication that SDAP addition altered IgG titres against the soya-bean proteins, glycinin and β-conglycinin.

Curing data were obtained from the carcasses of 54 boars (B), 58 gilts (G) and 46 castrates (C) reared from birth to slaughter at 89 kg live weight. Middle bacon rashers were compared for colour and incidence of fat splitting. The uptake of curing salts was similar for each sex group but carcasses of B retained proportionately 0012 less of the cure compared with G and C which did not differ significantly. Bacon yields from B, G and C at a final live weight of 88·6 kg were 40·6, 42·4 and 42·2 kg respectively. Sex did not influence the degree of splitting of the backfat layers in bacon rashers and had little effect on the colour of their lean tissue, but B compared with G and C tended to have a higher incidence of separation of the inner fat layer from the m. longissimus in the bacon rasher.

Immunisation against ovarian steroids has been shown to improve the reproductive performance of ewes. Using this principle the drug Fecundin was developed by Glaxo Animal Health Ltd. and is marketed by Coopers Animal Health Ltd. who supplied the drug for this study. The response to Fecundin was evaluated in ewes lambing in the spring under a wide range of commercial conditions in an ADAS co-ordinated trial.

ADAS Sheep Specialists and Advisers co-operated in locating and collecting the data from suitable commercial flocks and 2 EHF's with a minimum of 150 but more usually 200 ewes and where accurate lambing records could be obtained. Potentially naturally prolific types of ewes eg. Mules and Finn crosses were excluded. Approximately eight weeks before the rams were introduced all the ewes were condition scored and randomised to treatment or control. Treated ewes were injected with Fecundin and again 21-28 days later. At lambing the number of lambs born alive and dead and barren ewes were recorded in all flocks. Lambing dates, lamb birthweights and lamb survival were available in a limited number of flocks.

This study examined the comminution of fresh herbage, subsequent nutrient release, and the characteristics of swallowed boli from three physically and chemically contrasting forages during ingestive mastication by dairy cows. The extent and pattern of nutrient release will determine their availability to rumen microflora, and potentially influence their efficiency of use. The forages evaluated were perennial ryegrass (ryegrass, Lolium perenne L., cv Alto AR37), lucerne (Medicago sativa L., cv Torlesse) and chicory (Cichorium intybus L., cv Choice). Experimental design was a 3×3 cross-over with three forages and three consecutive 1-day measurement periods, conducted twice. Six non-lactating, pregnant, multiparous Holstein-Friesian×Jersey cows (Bos taurus) were used, with the first cross-over applied to three mature (10.1±0.61 years old; BW 631±64 kg) cows, and the second to three young (4.8±0.02 years; BW 505±19 kg) cows. Fresh cut forage was offered to the cows following partial rumen evacuation. Swallowed boli were collected directly at the cardia at the commencement, middle and end of the first feeding bout of the first meal of the day. Forage species did not affect the fresh weight of ingested boli (mean 169 g, P=0.605) but the proportion of saliva in boli varied between forage. Boli of chicory contained the greatest amount of herbage material and least amount of saliva, whereas ryegrass boli were the opposite. Boli fresh weight tended to increase as time in the meal progressed, but the age of the cow was not shown to affect any boli characteristics or nutrient release. Particle size reduction was affected by forage, with 31%, 38% and 35% of chicory, lucerne and ryegrass herbage reduced to <2 mm. There was little evidence of relationship between comminution and any physical or chemical characteristic of the forage, except in ryegrass where extent of comminution was moderately correlated with herbage strength. Proportional release of herbage soluble carbohydrate exceeded that of N during mastication. Differences in loss of N were moderately correlated with the amount of N in the herbage (R2=0.53) but herbage comminution was not strongly correlated with release of either N or carbohydrate. These findings illustrate the complex animal×forage interactions that occur during mastication, and that it is not possible to infer nutrient loss from herbage based on herbage characteristics as the driver for this differ between species.

Lambs were fed diets in which peat replaced equivalent alfalfa hay. Gains were depressed by proportionately 0·14, 0·32 and 0·56 due to 100, 200 and 300 g peat per kg, respectively, during a 63-day feeding period. Lambs fed peat required more dry matter per unit gain. Necropsy examination of heart, kidney, liver, spleen, lung, and pancreas revealed no gross abnormalities from feeding of peat. Rib eye area was reduced at 200 and 300 g dietary peat per kg. There were no differences in taste of cooked loin sections due to peat. These studies support the safety of feeding peat for use as a dietary carrier at 20 to 30 glkg diet or as a dietary diluent at higher levels.

1. For four consecutive years, each one of four herds of 13 cows and calves grazed land stocked and fertilized at one of the following combinations of rates (ha/cow, kg N/ha): 0·61, 82; 0·51, 82; 0·51,203 and 0·40, 203.

2. The Devon and Devon × British Friesian cows present in each herd reared calves by Devon bulls. Calving occurred indoors over the period February to April, the cows having been housed in early December.

3. Live-weight gains of calves to weaning in mid-October did not differ between herds in any year. Live-weight increase of cows over the grazing season was similar and substantial in all herds. On average pure-bred calves were 25 kg lighter at weaning than the cross-bred calves.

4. The main difference between treatments was in quantity of grass conserved and it was only in the herd kept at 0·51 ha/cow, 203 kg N/ha that enough was made to supply all the energy needs of the herd for a 150-day winter.

5. Gross margins/ha were greatest at the higher rate of nitrogen application but no further improvement was evident at the maximum stocking rate. The importance of maximizing output/animal is discussed.

Holstein-Friesian male calves, aged 160 to 450 days, and of live weight 180 to 530 kg, were used to determine the effects of dietary nitrogen level and dietary nitrogen source on performance. Experiment 1, tested dietary nitrogen level, and involved two trials with three dietary-nitrogen levels and equal dietary metabolizable energy (ME) 11·7 MJ/kg dry matter (DM). The crude protein (CP) level was reduced in the course of the trials by 40 g/kg, the experimental average CP in the diets being 146, 126 and 106 g/kg for the high (HP), medium (MP) and the low protein (LP) diets, respectively. The urea space (US) for estimation of body protein deposition and the rumen volume for calculation of empty body weight were measured in trial A of experiment 1. Experiment 2 involved four diets of equal ME concentrations; (11-7 MJ/kg DM), in three of which the CP contents were equal but from different sources: (a) 110 g/kg, all of it true protein (TP), negative control; (b) 130 g/kg, all of it TP; (с) 130 g/kg CP, 20 g/kg of it is poultry litter (PL) protein; (d) 130 g/kg CP, 40 g/kg of it is PL protein. Significantly lower US and ratio of US to live weight were found in the calves on the LP diet, from the age of 265 days than in the calves on the other diets. The ratio of US to live weight significantly decreased with increasing age in all protein level treatments. Until the age of 300 days the rumen volume was significantly higher on the LP diet than on the other diets. Calves on the HP diet had the highest daily gain and carcass gain. The recommendation to reduce the dietary protein as age increased to lower than 120 g/kg caused a reduction in the energy retained from the diet but protein deposition was not impaired. Protein deposition was impaired when the CP was reduced by 20 g/kg below the level recommended by the National Research Council. The inclusion of poultry litter in the diet, with ME concentration being maintained, did not reduce the rate of live-weight gain, and improved food conversion efficiency.

Carcass composition was measured on 133 Blackface ram lambs from a flock divergently selected for predicted carcass lean proportion. Prediction equations for different carcass components were developed using combinations of live weight and ultrasonic backfat and muscle depth. Both carcass lean and carcass fat proportion were best predicted using only live weight and fat depth, and a genetic transformation of the equation predicting carcass lean proportion was highly correlated (genetic correlation = 0·97) with the index on which the sheep were selected. Weights of carcass tissues were more accurately predicted than proportions. Lean weight was best predicted using live weight and muscle depth, and the weights of different fat components were best estimated using live weight, muscle depth and fat depth.

The equations predicting carcass lean proportion, carcass fat proportion, lean mass and fat mass had heritabilities of 0·29, 0·27 0·20 and 0·23, respectively. Heritabilities for carcass lean and carcass fat proportions, and the subcutaneous and intermuscular fat components were 0·43, 0·48, 0·24 and 0·49, respectively. Genetic correlations of the equation predicting carcass lean proportion with lean and fat proportions were 0·52 (s.e. 0·21) and –0·45 (s.e. 0·22), respectively. The same correlations for the equation predicting carcass fat proportion were –0·47 (s.e. 0·22) and 0·57 (s.e. 0·21). The equations predicting carcass lean and fat proportions were strongly correlated with subcutaneous fat proportion but weakly genetically correlated with intermuscular fat proportion.

Trials have previously shown that during the first 48 hours of life, new born piglets are reluctant to use forward-creep areas. In the neo-natal period, in order to prevent piglets lying in the danger-zone, luxury creep heating has been proposed. This comprises temporary heating at the rear and sides of the sow. On commercial farms, various luxury creep-heating systems are used. In an attempt to increase the precision and safety aspects of luxury creep-heating, a purpose-built device has been developed on a commercial farm. Trials were therefore undertaken, in co-operation with Eastern Electricity, to compare this system to a conventional forward-creep system.

A total of 124 litters supplied only with a 150 watt heater in the creep box (Control) was compared to 124 litters provided with the luxury regime. The supply line for the luxury device is shown diagramatically in Figure 1. It comprised a timber-mounted mains electricity power-line, temporarily suspended prior to farrowing above and behind groups of 4 sows. The line provided three 13 amp sockets for each litter and supplied a 300 watt dull-emitter located behind the sow and two 175 watt, dull emitters suspended in the side creep areas.

Previous studies have shown that reciprocal recurrent selection (RRS) would be ineffective in the early cycles of selection if over-dominant loci were at equilibrium gene frequencies in both selected populations. It is shown in the present study that response to RRS may be reduced by this unstable equilibrium even when gene frequencies are as much as 30 % removed from the theoretical equilibrium frequency. Reducing one population to a bottleneck of two individuals for one generation or more before initiating RRS (RRSB) was very effective in overcoming the unstable equilibrium. RRS with recurrent inbreeding, then outcrossing in both populations each cycle of selection (RRSC) was not effective in overcoming the unstable equilibrium, but yielded greater response per cycle after selection response began. The effectiveness of RRSC was inversely proportional to the heritability of the trait. Use of these modifications to increase the effectiveness of RRS in poultry breeding is discussed.

Crude protein concentration in diets based on high-moisture maize grain was increased using rumen degradable protein (RDP) or rumen undegradable protein (UDP). Treatment diets (numbers in parentheses indicate approximate RDP and UDP concentrations, g/kg dry matter (DM)) were: low-RDP (59, 80), high-RDP (79, 92), low-UDP (66, 67), high-UDP (69, 107, with maize gluten meal as chief UDP source) and high-UDP (71, 91, with fish, meat and maize gluten meals as UDP sources). Rumen pH and concentrations of volatile fatty acids, measured hourly for 12 h after feeding in four rumen fistulated Holstein steers, were unaffected by treatment (P > 0·05). Rumen ammonia-N concentration was greater for high-RDP (193 mg/1) than low-RDP (68 mg/1; P < 0·001). Within 12 h of feeding, ammonia-N concentration declined from 169 to 58 mg/1 for low-RDP and remained stable for high-RDP.

In a 56-day feeding trial using Holstein heifers (live weight 128 kg) and the first four treatments, RDP concentration had no effect on DM intake (P > 0·05). Lower DM intake (P < 0·01) for high-UDP (4·40 kg/day) than low-UDP (5·13 kg/day) was attributed to low palatability of maize gluten meal. Live-weight gain and food conversion efficiency were unaffected by treatment.

In a 56-day feeding trial using Holstein bulls (live weight 110 kg) and all treatments, RDP concentration had no effect on animal performance (P > 0·05). Food conversion efficiency increased (P < 0·001) when UDP concentration was increased only if UDP was supplied by a mix of fish, meat and maize gluten meals.

When RDP supply was not limiting to DM intake, protein source (amino acid composition) was better than protein degradability as an index of the feeding value of dietary protein.