Sires from British breeds are less likely to cause calving difficulties than sires from Continental breeds. Consequently, heifers have usually been mated to Aberdeen-Angus, Beef Shorthorn or Hereford sires although Continental sires produce bigger, faster growing calves which mature at heavier weights. However, information is available on calving difficulties for sires used in AI and this enables easy calving Continental sires to be selected.

A group of 70 Hereford x British Friesian heifers were allocated at random to be mated, using AI, to a progeny tested high performance easy calving Aberdeen-Angus or to an easy calving sire of the Blonde d'Aquitaine, Limousin and Simmental breeds.

Only one sire from each breed was involved. The heifers were mated to commence calving in mid August 1985. A combined PRID/PG (PRID, CEVA; prostaglandin ICI Estrumate) technique was used to synchronise oestrus in the heifers and they were served by AI at 72 and 96 hours after the PG injection.

The paper outlines the major problems in scientifically assessing the nature and quality of the man-animal interface and the difficulties in isolating its effects on animal production. Research epistemologies in this area are thwart with difficulties as it is virtually impossible to isolate individual factors. For example, while it is possible to devise ‘pleasant’ and ‘unpleasant’ handling treatments; as defined by level and nature of the physical interaction of the human body with that of the animal; it is not possible to separate physical handling from aspects such as voice tones, gestures, smell, sound of foot movements, or other ‘vibes’ transmitted in the experiment. Thus, any changes in ‘production’ may arise from a number of inter-woven components. It is also of relevance that the quality of the man-animal interface is a perceived construct and that the animal may perceive both applied ‘pleasant’ and ‘unpleasant’ stimuli as undesirable. Limitations of research paradigms are raised, for example, in experimental situations the environment may well be ‘richer', and with more humans present, than in commercial situations. The nature of the interface may thus be somewhat different.

Current ration formulation schemes for calculating the feeding requirements of dairy cattle are primarily based upon empirical relationships between nutrient availability and milk production. Although these schemes can provide reasonable estimates of nutrient requirements, they are inadequate at predicting the responses in milk yield and composition to changes in nutrient availability. Clearly, a more integrated approach is required where the predictions are based on the metabolic fate of the absorbed nutrients. An ability to achieve this requires knowledge of the precursors used for milk protein synthesis and how nutrient intake influences their partition to the mammary gland for utilisation in milk protein biosynthesis.

Some reports have suggested differential tissue deposition of dietary trace minerals such as Zinc (Zn) when supplied to farm animals either chelated to amino acids or as inorganic salts. To test this hypothesis, an experiment was conducted to determine the ultimate tissue distribution of Zinc in rats fed either a radioactively-labeled 65Zn-chelate or 65ZnSO4. The 65Zn-chelate was prepared by heating a solution of 65ZnSO4 and an equimolar mixture of glycine and methionine for 5 minutes at 90°C. The resulting chelate was then separated from unincorporated 65ZnSO4 by gel filtration chromatography. Ten 25-d old male wistar rats (mean weight 34.5 g) were randomized by weight into two groups (n = 5/group), fasted for 18 hours and given 0.4 ml (8 μg Zn, 1 μCi65Zn) of one or other labelled solution by gavage. Four hours later, animals were returned to their normal diet for the duration of the experiment. The 65Zn activity of the animals was determined two hours after administration and daily thereafter for 7 days.

Lactic acid is the predominant organic acid found in well preserved silages, accounting for up to 150 g/kg dry matter. However, lactic acid has been shown to have a depressive effect on the voluntary intake of hay and silage by cattle (Thomas et al, 1980; Montgomery et al, 1963). The objective of the present study was to investigate how the response of cattle to short term intra-ruminal infusions of lactic acid might be mediated, using fistulated steers adapted to diets of chopped hay or silage by measuring the patterns of feed consumption during the day, together with changes In the concentration of metabolites within the rumen.

Crowding of pigs can adversely affect both performance and welfare of the individual animal, but high costs of buildings encourage increasing stocking rates in commercial practice. Current welfare codes (MAFF, 1983) recommend minimum lying space allowances for pigs but do not specify the total area which should be given. Conflicting experimental and commercial recommendations exist for the optimum space allowances for growing pigs in housing with fully slatted floors, when separation of lying and dunging areas is less important for hygiene and thermoregulation. This experiment was carried out to examine the effects of different space allowances in such housing on pig performance and carcass quality.

Skatole and indole, compounds formed in the large intestine by microbial breakdown of tryptophan, are associated with carcass taint (Hansson et al., 1980). The present work involved the development of a method for detecting the absolute values of the analytes in fat and faeces. The effect on faecal excretion of skatole was also examined following infusion of skatole directly into the caecum. Finally as substrate effects the type and extent of fermentation in the large intestine, different diets were fed and the corresponding faecal and fat skatole levels were determined.

Skatole analysis involved homogenising adipose tissue with methanol and removal of fat by cooling and filtering. Solid phase extraction columns concentrated the analytes to produce samples which gave good resolution by gas liquid chromatography (Porter, Hawe and Walker, 1989). Due to higher levels of skatole in faeces, no concentrating phase was required before detection.

Experiments designed to test animal responses to sward manipulation suggest that ewe performance and lamb growth are positively related to herbage mass and thus sward height (1,2,3,). From this component research, it is suggested that to maximise herbage production and animal performance during the main grazing season, sward heights should be maintained within the range of 4 to 6 cm; herbage mass should not exceed 1600 kg DM/ha (4,2). This trial was set up to test the efficacy and sensitivity of this approach in a set-stocked, grass lamb finishing system.

The objective of the experiment reported here was to provide the UK farmer with sufficient information to allow economic utilisation of space in flat-deck accommodation without a reduction in performance of the weaned pig.

Two experiments at separate sites were used to compare different methods of achieving the same stocking density. At site 1 pen size was altered by means of a moveable partition while at site 2 it was the number of pigs per pen which was altered.

The deep body temperature of the newly born piglet (39°C) in many circumstances drops immediately after birth. A drop in body temperature of 2°C or more is considered to constitute chilling. When pigs are chilled they become lethargic and are more prone to overlying and starvation (Stephens, 1971). Because chilled piglets are less successful in competing for a suckling position and in obtaining colostrum they are more prone to disease such as scouring (Kelley, 1982). Lynch (1983) found in a farrowing house temperature of 24°C, 23 and 3 per cent of piglets had a body temperature of 37°C or less at 1 and 24 hours of age respectively. When farrowing house temperature was at 17°C, the proportion of chilled pigs (body temperature below 37°C) was 72,59 and 6 per cent at 1, 24 and 48 hours of age respectively. Thus, the incidence of chilling after birth can be extremely high and the consequences are likely to be serious. An experiment was carried out to investigate approaches for minimising the drop in piglet body temperature after birth and to examine the effects on piglet survival and growth.

Partial storage feeding (grazing during the daytime and housing overnight) is becoming an established management system after turnout in the spring. Ad libitum grass silage is the most common overnight feed. However, some farmers do not have adequate silage available and a straw mix is a possible alternative feed. There is little information available concerning the optimum energy content of straw mixes (or other forages) used for partial storage feeding. In this experiment 3 straw mixes were fed with different energy contents.

In a continuous design experiment lasting 8 weeks (18 April to 12 June 1985) 60 autumn calving Friesian dairy cows and heifers were set stocked together during the daytime at 10 cows/ha. They were housed overnight and straw mixes, with low (L), medium (M) or high (H) metabolisable energy (ME) contents, were fed ad libitum each to 20 cows. In addition an average of 2.3 kg concentrates were offered daily. The grazing area was a perennial ryegrass ley which received 224 kg N, 13 kg P2O5 and 13 kg K2O/ha. The mean composition of the straw mixes, herbage and concentrate are given in Tables 1 and 2.

The inheritance of the time taken to react to halothane anaesthesia was examined as a possible quantitative measure of penetrance, which might allow the advantage of the halothane gene in lean content to be separated from its disadvantage of stress susceptibility. Restricted maximum-likelihood analyses were conducted on a total of 2207 pigs from 118 sire families in British Landrace and Pietrain-Hampshire lines selected for a high frequency of positive halothane reaction over 6 years. Reaction time averaged 94 s with a CV of 0·53, and was significantly influenced by line, season and live weight, but not sex. Estimated heritabilities averaged 0·07 (s.e. 0·06) and 0·16 (s.e. 0·12) in the two lines respectively, giving a pooled estimate of 0·09 (s.e. 0·05). Due to the high CV, family selection with a heritability of around 0-1 could be expected to give a rapid genetic change in reaction time. It is therefore concluded that selection for slower reaction to halothane could provide a means for reducing the incidence of stress susceptibility while retaining the advantage of the gene in lean content. However, further evidence is required on the correlation of reaction time with stress susceptibility and lean content.

An extended milking interval of 24 h (24-h milking interval (24h-MI)) constitutes the acute phase of cow adaptation to once-daily milking (ODM). A recent trial including 724 24h-MI challenges demonstrated that milk yield responses to this acute phase of ODM are highly variable (from+22% to −52% of milk yield when switching to the 24h-MI, mean=−25.3%) and that factors such as stage of lactation parity and milk yield level influenced cows’ responses but did not account for all individual variability. Additional traits related to physiological, immune and behavioural adaptation were measured on a subset (96 observations) of this data set. This study aimed to determine (1) the relationship of these traits with cows’ milk yield responses, (2) their ability – combined with previously identified traits – to help predict milk yield responses to 24h-MI (adaptive profiles). The 24h-MI challenge consisted of three successive periods: one control week of twice-daily milking (cTDM), one single day of 24h-MI and then 13 days of TDM (pTDM). Milk yield responses to the 24h-MI (corrected for effects of stage of lactation, parity, milk yield level and milk yield) were related to physiological traits measured during cTDM (milk flow rate, presence or absence of interleukin-8) and to their changes during the 24h-MI (absolute increase in milk flow rate and relative udder distension). Analysis of associations between milk yield responses, stage of lactation, parity, milk yield level, proteolysis, udder expansion and immune traits found three adaptive cow profile clusters. Cows in cluster 1 had a less compliant udder than cows in cluster 2, and they lost more milk during the 24h-MI than cluster-2 and cluster-3 cows. After resuming twice daily-milking (TDM), cluster-2 cows fully recovered the milk they had lost during the 24h-MI. On the opposite, cluster-3 cows did not recover the milk they lost, likely due to udder inflammation during cTDM, as suggested by elevated concentrations of interleukin-8 in their milk. These results combining new traits with stage of lactation, parity and milk yield level constitute a first step towards predicting individual cow responses to a 24h-MI.

Heterosis for growth rate in pigs is usually expressed, and reviews of European and North American studies have been given by Sellier (1976) and Johnson (1981). Kennedy and Moxley (1980) observed heterosis of 0·044 to 0·067 for weight at 154 days and attributed some of the crossbred advantage to heterosis for resistance to atrophic rhinitis. Similarly, McGuirk, Bourke and Manwaring (1978) attributed some of the heterosis for growth rate in sheep to heterosis for resistance to pneumonia. Although little attention has been paid to interactions between heterosis and health environment, Barlow (1981) concluded from an extensive review of studies involving farm and laboratory animals that heterosis is environment dependent and is enhanced by increased stress. Sellier (1976) commented that it would be useful to examine the degree of heterosis with ‘specific pathogen free’ pigs raised in a healthy environment, and this study examined heterosis for days to 90 kg in Yorkshire × Landrace pigs under three different environments with respect to health conditions.

In order to evaluate heat stress and circadian rhythm 46 nulliparous rabbit does with a BW of 3.67 ± 0.05 kg (s.e.) were used. They were clipped once or not and rectal temperature, feed and water intake were recorded for 24 h. From this group, 43 rabbit does were mated 7 days after rectal measurements, and randomly assigned to one out of two breeding systems (including in both systems rabbit does that had been clipped or not). In the control one (C) rabbit does were mated 14 days after parturition and litter weaned at 35 days of age, and in the extensive one (E) they were mated 21 after parturition and weaned at 42 days of age. Rabbit doe and litter performance were recorded for 6 months (first three cycles). Two hundred twenty-eight weaned rabbits were divided into two cage sizes: 0.5 and 0.25 m2 with eight and four rabbits per cage, respectively, to study growing performance. Farm and rectal temperatures were minimal and feed and water intake maximal during the night (P < 0.001). Unclipped rabbit does showed higher rectal temperature (P = 0.045) and lower feed intake (P = 0.019) respect to clipped does, which are symptoms of heat stress. Neither breeding system nor cycle number influenced fertility, total number of kits born, born alive or dead per litter (91.6%, 6.98, 5.80 and 1.19 on average, respectively). Kit mortality during lactation tended to increase in E compared with C group (48.5% v. 63.4%; P = 0.070), reducing the number of kits at weaning per litter by 33% (P = 0.038). It also increased in the second and third cycles compared with the first (P ⩽ 0.054). It resulted that feed efficiency (g weaned kits/g feed intake does + litter) tended to decrease in E respect C group (P = 0.093), whereas it was impaired successively from the first to the third cycle by 48% (P = 0.014). Growing rabbits from the E group were heavier at weaning (by 38%; P < 0.001), showed a higher feed intake (+7.4%) and lower feed efficiency (−8.4%) throughout the fattening period (P ⩽ 0.056) respect to C group. However, age at slaughter was not different respect to C group (77.3 days on average). Cage size had minor influence in growing performance. In conclusion, rabbit doe and litter productivity impaired when lactation is extended from 35 to 42 days and along successive reproductive cycles.

Previous studies have shown that the interaction between limiting vitamin A (VA) and an alcohol dehydrogenase 1 C (ADH1C) variant in beef cattle results in increased intramuscular fat in the longissimus thoracis muscle in one genotype when fed low dietary VA. Although quality grade is important for increased profitability and improving taste characteristics of beef products, limiting VA too drastically can impair animal welfare. The objectives of this study were to determine if this marker-assisted management strategy would be effective, and whether any impairment in immune function would occur in a feedlot setting. Mixed breed beef steers (n=2000) were sorted into 40 feedlot pens so that all combinations of ADH1C genotype (TT or CT), VA level (50% or 100% of recommended) and hormonal implant status (implanted (IMP) or non-implanted (NI)) were equally represented within the population. The VA×ADH1C interaction was not observed. An implant status × ADH1C interaction was observed with average daily gain (ADG; P=0.03). Steers that were IMP and CT had higher ADG than IMP TT (CT=1.69 and TT=1.62 kg/day), whereas both genotypes in the NI steers were lower (CT=1.29 and TT=1.32 kg/day). Implant status was shown to affect dry matter intake (DMI; IMP=8.55 and NI=7.87 kg; P<0.01), total days-on-feed (IMP=164.4 and NI 210.5 days; P<0.01), USDA yield grade (YIELD; IMP=2.40 and NI=2.77; P<0.01), marbling score (MARB; IMP=392 and NI=455; P<0.01), longissimus thoracis area (LTA; IMP=85.0 and NI=80.7 cm2; P=0.01) and backfat thickness (FAT; IMP=8.0 and NI 10.0 mm; P<0.01). Overall, IMP animals finished on fewer total days-on-feed with higher ADG, DMI, larger LTA, and lower YIELD, MARB and FAT. To investigate immune function parameters, crossbred steers (n=18) were selected from a prior feeding trial so that all combinations of ADH1C (TT, CT and CC) and VA (25% or 75%) were equally represented. Blood cell count analysis and peripheral blood mononuclear cell proliferation and stimulation assays were conducted. None of these immune parameters were affected by VA level. Treatment and mortality records were examined in the 2000 steer population, where no correlations with ADH1C, implant status or VA level were observed. Due to no VA × ADH1C interaction, this nutrigenetic marker-assisted management strategy is not effective at this time in commercial beef cattle feedlots, however, supplementing VA at a level as low as 25% of recommended in finishing rations would likely not result in signs of immune dysfunction.

Days elapsed from the mid point of the anoestrous period to first (DF) and last (DL) oestrus of the breeding season and duration of this breeding season (DD) within a flock of 60 adult Lincoln ewes are reported in this note. All traits showed considerable variation and the phenotypic correlation between DF and DD was −0·57 (P < 0·01) while that between DL and DD was 0·87 (P < 0·01). However, DF was not correlated with DL (P = 0·10).

The value of E, defined as the weight of carcass produced per 100 units of digestible organic matter (DOM) consumed, was used to assess the biological efficiency of meat production in housed sheep. The effect on E of weaning lambs at 4, 6, 8, 10, 12, 14 and 16 weeks post partum was studied for a number of different breed crosses. The age at which lambs were weaned was found to have little effect on the growth rate of lambs and no significant effect on the biological efficiency with which sheep produce meat.