Whole milk was given once daily to three groups each of 18 Friesian heifer calves and concentrates and hay were also available. Calves in one group received 2·4 kg milk/day and in a second 3·0 kg milk/day and in both of these groups individual calves were weaned when their daily intake of concentrates reached 400 g. In the third group the calves received 3·0 kg milk/day and were weaned after 28 days. Concentrate and hay intakes were not significantly affected by the treatments. Mean growth rate over 56 days increased with increasing quantity of whole milk offered but the differences between treatments were not significant. The performance of calves given whole milk was compared with the performance achieved in previous experiments where milk substitute was given. It was estimated that 1 kg whole milk gave the same live-weight gain as 170 g milk-substitute powder. From this estimate price/cost relationships were determined to indicate when whole milk or milk substitute should be fed to calves.

To-day we are considering the possibilities of improvement for beef production, and it may be useful at the outset to examine briefly the methods which were successfully employed by some of the great improvers of the past.

In Bakewell's time, 1726–1795, the cattle of the English Midlands were descended from every sort which had come to Britain, except that there had apparently been little mixing with the Scandinavian hornless cattle. Hornless cattle were still confined mainly to coastal areas. The colours and colour patterns varied greatly, and some cattle were the full size of the Dutch, while others were much smaller. Some had short horns ; others had the long wavy horns which had come in with the Roman cattle, so they were generally called Longhorns. It is perhaps worth recalling that the cattle of those days were a sort of non-specialized general purpose, or actually triple purpose. The bigger beasts had been valued for draft, the cows for milk, and the carcasses of both draft-bullocks and cows were ultimately of value for beef. Incidentally, there is little doubt that the Dutch cows were the best milkers. The breeds which became the Shorthorn were dual purpose, but were bred for a long period for beef (from the 1790's to the 1870's).

For any programme of livestock improvement to be successful it is necessary to investigate the mode of inheritance of the various economic characters and their relative importance in the given set of circumstances. Many practical attempts at agricultural improvements have failed to give satisfactory results because the objective has not been well co-ordinated with the overall economic, environmental and even social conditions.

In this paper the possibilities of genetic improvement of a flock of Welsh Mountain sheep will be reviewed in the light of the results of investigations carried on at the College Farm of the University College of North Wales, Bangor, from 1949 to 1955. The investigations were made to determine the relative values and mode of inheritance of several basic measurable characters in the flock of 600 breeding ewes managed under typical hill conditions.

A comparison of the patterns of LH and FSH secretion was undertaken in lines of Finn sheep selected for and against high ovulation rate. Mean ovulation rate was significantly higher in the high line ewes (mean 4·1) compared with both the control (mean 2·5) and low line (mean 2·7) ewes (P <0·01). The pre-ovulatory LH peak occurred significantly earlier in the high line ewes (mean 52·1 h) compared with both the control (mean 65·0 h) and low line (mean 59·0 h) ewes (P < 0·05). While mean LH pulse frequency and overall mean LH concentrations were both significantly higher during the follicular compared with the luteal phase of the cycle (P < 0·05), there were no consistent relationships between patterns of pulsatile LH secretion and ovulation rate among the three selection lines. Plasma FSH concentrations remained significantly higher over the entire follicular phase of the oestrous cycle in the high line ewes compared with both the control and low line ewes (P < 0·05). It is suggested that the ovulation rate achieved by high line ewes may be causally related to their higher follicular phase FSH concentrations.

Severe feather-pecking (SFP) persists as a highly prevalent and detrimental behavioural problem in laying hens (Gallus gallus domesticus) worldwide. The present experiment investigated the association between feather-eating and plumage damage, a consequence of SFP, in groups of free-range, ISA Brown laying hens. Single feathers were placed on the floor of the home pens. Feathers were sourced from seven different birds. A total of 50 birds in six pens with extensive plumage damage were compared with birds in six control pens with little plumage damage at 41 to 43 weeks of age (n=12 pens, 600 hens). Birds in pens with extensive plumage damage ingested more feathers (F=8.1, DF=1, 8, P=0.02), and also showed shorter latencies to peck at (χ2=54.5, DF=1, P<0.001), and ingest feathers (χ2=55.6, DF=1, P<0.001). Birds ingested feathers from a bird in the free-range facility, in which the testing took place, more quickly than from a bird housed in a separate cage facility (χ2 = 39.0, DF=6, P<0.001). A second experiment investigated the predictive relationship between feather-eating and plumage damage. Feathers were presented to 16 pens of 50 pullets prior to the development of plumage damage, at 15 weeks of age, and then to the same hens after plumage damage had become prominent, at 40 weeks of age. Birds had a higher probability of ingesting feathers (F=142.0, DF=1, 231, P<0.001), pecked feathers more times (F=11.24, DF=1, 239, P<0.001), and also pecked (χ2 = 127.3, DF=1, P<0.001) and ingested (χ2=189.3, DF=1, P<0.001) the feathers more quickly at 40 than 15 weeks of age. There was a trend for an interaction, where birds pecked feathers from the rump more times than feathers from the back at 40 weeks of age (F=3.46, DF=1, 237, P=0.06). However, a lack of variability in plumage damage between pens in this experiment precluded investigation of the predictive relationship. The results from the present study confirm the association between feather-eating and plumage damage, and suggest that birds may prefer feathers from particular body areas and from particular hens. Future experiments should focus on elucidating whether feather-eating may act as a predictor of SFP.

The age at which the four pairs of permanent incisors emerged, and the interval between first emergence and the attainment of full size, was recorded from observations taken every 2 weeks on 332 female cattle of a herd comprising the Ayrshire, Friesian and Jersey breeds, and the reciprocal crosses among them.

The 1st pair of incisors emerged at a mean age of 101 weeks of age and later pairs at approximately 30-week intervals, with the s.d. increasing proportionately from 7 to 14 weeks. Full size of the incisors was attained, on average, 4·0, 2·4, 3·0 and 5·6 weeks after the initial observations on incisor pairs 1 to 4 respectively.

Breed (or cross) and season of birth significantly affected the age at emergence of the 1st and 2nd pairs of teeth, and breed also affected the age for the 4th pair. Relative to the Friesian breed, an Ayrshire parent delayed emergence of both 1st and 2nd incisor pairs by approximately 4 weeks, and a Jersey parent delayed emergence of all four pairs. The maternal effect was opposite in sign to the effect of breed substitution; in particular, a Jersey dam caused a reduction in the age at emergence. There was no evidence of heterosis in the crosses. On average, each pair of incisors erupted approximately 4 weeks earlier for cows born between October and December than for those born in the period April to June.

Age at calving, lactation length, milk yield, body weights and the ratio of 18-month body weight to that at 42 months (as an estimate of proportion of maturity) were not significantly correlated with the dental traits. Correlations between age at emergence of adjacent incisor pairs were approximately 0·7, a value higher than that between pairs separated by longer time intervals.

Two experiments, experiment 1 with six steers in a 3 × 3 Latin-square design and experiment 2 with four wether sheep in a cross-over design, were conducted to study the effect of species and ammonia treatment on intake and utilization of the energy of untreated wheat straw. Treatments were: (1) untreated wheat straw offered ad libitum on top of a basal diet (B) consisting of hay (0·25) and grass pellets (0·75) (UWS), (2) ammoniated wheat straw offered ad libitum plus B (AWS) and (3) ammoniated wheat straw offered at a restricted level plus B (AWS-). B was offered as a maintenance diet for both species and AWS- was only studied in steers. Voluntary intake of AWS zvas higher than that of UWS. No significant differences emerged between whole rations UWS and AWS with regard to energy digestion (ED), energy metabolizability (ρ = metabolizable energy (ME) I gross energy (GE)) and losses of digestible energy (DE) in urine and methane (average 187 J/KJ DE), but the efficiency of utilization of ME for growth (kg) was significantly higher for AWS than for UWS. ED and ρ of the straw part of the ration was significantly higher for AWS than for UWS. AWS- and AWS did not differ significantly with regard to ED, ρ and DE losses in methane and urine. Steers had a higher intake per kg0·75 per day than wether sheep. Across species, digestible energy intake (DEI) of the whole ad libitum fed diets was related to live weight (M)0·946 (s.e. of exponent 0·0152). ED and ρ of the straw part of the rations did not differ significantly between species, but steers had a significantly higher ED and ρ of β than wether sheep. Steers excreted a significantly lower proportion of DE in urine and a significantly higher proportion of DE in methane than did wethers. Total energy losses in urine and methane, however, did not differ between species.

Two feeding trails were made and in both all the diets given contained about 11 MJ metabolizable energy (ME) per kg dry matter (DM).

In trial 1, diets containing three concentrations of crude protein (CP) were given to a total of 84 Friesian bulls in each of three stages of growth. They were, in stage 1 (150 to 250 kg live weight) 130, 145 and 160 g CP per kg dietary DM; in stage 2 (250 to 350 kg live weight) 110, 130 and 145 g CP per kg dietary DM; in stage 3 (350 kg to slaughter) 95, 110 and 130 g CP per kg dietary DM. In stages 2 and 3, the source of supplementary nitrogen at each CP concentration was either soya-bean meal or non-protein nitrogen (NPN) giving six combinations of concentration and source of dietary CP. Live-weight gains in stage 1 were 1·52, 1·60 and 1·58 kg/day respectively (P > 0·05). In the stages involving both concentrations and source of nitrogen (soya-bean meal in parentheses), the mean daily live-weight gains were (1·40), 1·38, (1·32), 1·34 (1·34) and 1·31 kg for stage 2 (F > 0·05) and (1·14), 1·14, (1.24), 1·16, (1·06) and 1·08 kg for stage 3 (P < 0·05), for the diets of 130, 145 and 160 g CP per kg diet respectively.

Trial 2 consisted of six stages of growth, the first five of 45 days duration and the sixth of varying length up to a predicted slaughter weight, and seven dietary treatments. Treatment 1 was a negative control (NC) with a dietary CP concentration of 90 g/kg DM. For the other six treatments two concentrations of dietary CP were given; 120 g/kg and 140 g/kg in stages 1 and 2 and 100 g/kg or 120 g/kg in stages 3 to 6. Dietary CP concentration was increased by the addition of NPN, fish meal or soya-bean meal. A total of 98 Friesian bulls were used with an initial average live weight of 185 kg. Daily gain of the NC group in the six stages of the trial was 0·86, 0·97, 101, 1·13, 1·07 and 1·00 kg for stages 1 to 6 respectively. From the results it was concluded that feeding NPN is not efficient at live weights lower than 250 kg and that there is no advantage to feeding fish meal over soya-bean meal in diets of medium energy concentration at live weights heavier than 250 kg.

The objectives of this study were (1) to estimate herbage intake in spring and late summer in Danish Friesian steers during their first grazing season on ryegrass/white clover pasture and (2) to investigate the effect of different winter feeding levels on subsequent herbage intake in Danish Friesian steers weighing more than 450 kg. In experiment 1, herbage intake was estimated in 18 to 20 steers with a mean live weight of 210 kg (s.e. 8•0 kg) and 312 (s.e. 8•9) kg in May/June and August respectively. In experiment 2, 22 steers were allocated to two feeding treatments in their second winter with expected daily live-weight gain of 500 g (LOW) and 800 g (HIGH). The steers weighed 440 (s.e. 15•8) kg (LOW) and 531 (s.e. 9•2) kg (HIGH) at the time of turn-out on to a ryegrass/white clover pasture. Herbage intakes were estimated in June using, as in experiment 1, the alkane bolus technique. Faeces and herbage samples were analysed for alkanes to estimate herbage intake, digestibility and botanical composition of intake. The weight gains (kg/day) were 1•156 (s.e. 0•69) and 1•054 (s.e. 0•87) in May/June and August respectively (experiment 1) and 1•592 (s.e. 0•137) and 1•273 (s.e. 0•116) in June in LOW and HIGH respectively (experiment 2). Daily herbage intake (kg dry matter (DM) per steer) estimated by alkanes C32 /C33 were 5•2 (s.e. 0•26), 9•4 (s.e. 0•28) in May/June and August (experiment 1) (P < 0•001) and 12•0 (s.e. 0•50) and 10•4 (s.e. 0•41) in LOW and HIGH (experiment 2) (P < 0•05) respectively. The diet of steers contained primarily ryegrass leaves (0•70 to 0•90) and ryegrass stems (0•10 to 0•30) and clover (0 to 0•02 and 0•18 in experiment 1 and experiment 2 respectively). It was concluded that (1) steers during their first grazing season can maintain herbage intake per kg live weight during the grazing season from May to August, and (2) steers weighing more than 450 kg are able to increase herbage intake along with compensatory growth.

Six comparable groups, each of 4 castrate pigs, were used to compare the feed value of maize and sorghum as estimated by live-weight gain, food conversion efficiency, slaughter quality and ham composition.

The maize ration contained 40% yellow maize and the sorghum ration 40% Sorghum vulgare subglabrescens, all other ingredients being the same for both diets.

No statistically significant differences were found between the maize and sorghum pigs with regard to the criteria mentioned.

It is concluded that no difference exists between the feed value of the maize and the sorghum used. This result is in better agreement with the net energy values of maize and sorghum as calculated by the formula of Hoff-mann and digestion coefficients for pigs, than with “classical” starch equivalents.

There is a growing body of evidence to suggest direct involvement of the cytokines interleukin-1 (IL-1), interleukin-6 (IL-6) and tumour necrosis factor-α (TNF-α) in the initiation of skeletal muscle catabolism and depressions in growth performance as a result of diseases, while TNF-α and IL-6 are presumably under the control of IL-1. An experiment was conducted to investigate whether an interleukin-1 receptor antagonist (IL-1ra) could reduce growth depressions in a model of subclinical disease in growing pigs. In this study, 24 crossbred barrows and gilts were randomly assigned to three treatments: (1) healthy control (HC), saline infusion; (2) sick control (SC), infection with Mycoplasma hyopneumoniae and vaccination with porcine reproductive and respiratory syndrome modified live virus (PRRSV) vaccine and saline infusion; (3) SC plus infusion with IL-1ra (SC+IL-1ra). An additional six pigs were killed at the initiation of the trial to determine initial body composition for estimation of carcass nutrient retention rates. During the 28-day experimental period, the SC pigs had growth performance similar to that of the HC pigs and the highest levels of plasma cytokines (P<0·10). The SC+IL-1ra pigs had growth performance similar to the HC pigs, but the SC+Il-1ra pigs tended to have higher growth rates than the SC pigs (P<0·10), the highest carcass protein accretion rate (P<0·10) and similar levels of plasma cytokines compared with the HC pigs. Plasma levels of insulin-like growth factor-1 (IGF-1) on day 22 tended to be higher (P<0·10) in the HC pigs compared with the SC or SC+IL-1ra pigs and treatment×sex interaction was observed on day 29; the IGF-1 levels tended to be higher in SC+IL-1ra gilts and SC barrows (P<0·10). These results indicate that infusion with IL-1ra in a model of subclinical disease helps attenuate the catabolic effects of immune system stimulation.

The coat of 16 Wiltshire × Wensleydale lambs was investigated and all were woolly, with no halo hairs on the back. The bulk of the coat consisted of curly-tip fibres, and most lambs had Valley (8) or Plain (6) fibre-type arrays, only two having Ravine arrays.

There was little difference in diameter between the primary and secondary fibres in the skin, and some evidence of ‘checking’ in the central primaries. The secondary/primary follicle ratio of 4·26 compared with a mid-parent value of 4·5. There was less latticed medullation in the crossbreds than in the Wiltshire.

The adult fleeces were visually similar to those of the Wensleydale and were intermediate in weight and staple length between the parent breeds. These findings could have practical application in the improvement of ‘hair’ sheep, in that a first cross with the Wensleydale would have a fleece of medium wool lacking hair or kemp.

Two in vitro experiments were conducted in order to determine if microbial fermentation of Eragrostis curvula hay is depressed by high levels of added tallow. Two levels of tallow, to reach 0.06 (T6) and 0.12 (T12) of the ether extract (organic matter basis) in food were compared with a control (T0, 25 g ether extract per kg). The first experiment studied the pattern of gas production. From 24 h onwards, gas volume for T0 was higher (P < 0.05) than for T6 and T12. However, lag time was shorter with tallow, probably because of utilization of the released glycerol. Fermentation of a similar amount of fat included in T6 and T12 as the only substrate (fat-6 and fat-12) depressed gas production compared with the blank, irrespective of fat level. In a second experiment, characteristics of microbial fermentation were studied, including volatile fatty acid (VFA) production, bacterial adhesion to fibrous particles (measured according to purine bases concentration) and polysaccharidase and glycosidase activities, at 6, 12, 24 and 48 h incubation. Total VFA was higher (P < 0.05) in T0 compared with T6 but not with T12. Acetate: propionate ratio diminished with tallow in the food. Higher total xylosidase (P > 0⋅05) and glycosidase (P < 0⋅001) activities were observed for T0 than for T6 and T12 and similar responses were observed regarding specific activities. Bacterial adhesion was not different between T0 and T6 but it was smaller in T12. The inhibition of microbial fermentation by tallow addition is more related to specific polysaccharidase and glycosidase activities, rather than to a depressed bacterial adhesion.

We investigated if sexual behaviour of rams can be assessed with an electronic Alpha-Detector (AD) which automatically records mounts of mating rams. To evaluate the rams’ libido (i.e. all sexual activities), we used six intact and six vasectomised rams in pen tests in three different seasons (late spring, autumn and early spring). The pen tests consisted of 30-min visual observations of each ram placed in a group of six Merino ewes (three ewes in oestrus and three ewes not in oestrus). In the pen tests, sexual behaviour was recorded and divided into two categories: pre-copulatory and copulatory. For validation purposes, during the pen tests the 12 rams were equipped with the AD and the number of times the 18 oestrous ewes were mounted were counted over a period of 3 days. Of the 1191 mounts visually identified in the six 30-min sessions, 1026 were recorded automatically by the AD (i.e. 94%). The paddock test is an automated method consisting of the same rams wearing an AD and placed in a flock of ~250 Merino ewes on two occasions (late spring (spring 1) and early spring of the following year (spring 2)), their copulatory activities were automatically recorded over a 5-day period. The results of the pen tests in the three seasons revealed no difference between the two types of rams (breeding v. detecting rams). Based on live observations high correlations (r=+0.81, P<0.003 for breeding and r=+0.76, P<0.02 for detecting rams) were found between pre-copulatory and copulatory behaviours. The libido of the two types of rams measured in pen tests showed high repeatability across the three seasons (83 and 75%, P<0.05 for copulatory and pre-copulatory behaviours, respectively). When measured automatically in paddock tests over two consecutive springs, even higher repeatability was observed in both breeding (94%; P<0.01) and detecting rams (97%; P<0.004) in the number of mounts. In addition, high correlations (+0.89<r<+0.94) between copulatory behaviours, as measured by live observations, and those measured by the AD were obtained. The automatic measurement of ram libido in paddock tests appears to be more reliable than pen tests and far less time consuming. We therefore recommend this automated method to estimate the libido of rams. In addition, this method can be used at any season of the year provided that ewes in oestrus are present in the flock.

An electronic meat-measuring equipment (EMME) determination (average of three consecutive readings) and backfat thickness (averaged over two sites) were taken on each of 107 live Yorkshire pigs weighing approximately 110 kg. After slaughter, 10 carcass traits: killing out, grade fat (fat thickness at maximum loin of split carcass), in. longissimus area, total and individual weights of the four untrimmed primal cuts (butt, picnic, loin and ham) and total weight of lean and subcutaneous fat in the four primal cuts, were measured and used to evaluate the EMME and ultrasound backfat probe, alone and in combination, in predicting carcass merit. Value of prediction was measured as significant improvement in correlation over a base model (A/?2). After adjustment for live weight and treatment (diet, sex and housing) differences, the EMME alone was significant in predicting grade fat (A/?2 = 007), weight of the four untrimmed primal cuts (A/?2 = 0·03) and weights of ham (A/?2 = 0·04), lean (A/?2 = 0·17) and subcutaneous fat (A/?2 = 0·08). Backfat thickness alone was significant in predicting grade fat (AR2 = 0·21) and the weights of loin (AR2 = 0·03), ham (AR2 = 0·02), lean (AR2 = 0·09) and subcutaneous fat (AR2 = 0·42). Their combined information was superior in predicting fat thickness (AR2 = 0·24), weight of lean (AR2 = 0·21) and weight of subcutaneous fat (AR2 = 0·44). Similar results were obtained when treatment effects were ignored. Correlations of the EMME number with fat thickness, weight of total lean and total subcutaneous fat were 0·31, 0·49 and -0·30, respectively. Correlations of backfat thickness with grade fat, weight of total lean and total subcutaneous fat were 0·53, -0·35 and 0·72, respectively.

The Friesland or East Friesian breed of sheep is a heavy-milking type with a high level of prolificacy. The progeny of the cross with the Scottish Blackface female sheep (ewe) have been shown to have larger, heavier litters in a good lowland environment compared with crossbreds derived from other crossing sires (Boaz, Jones and Smith, 1980; British Friesland Sheep Society, 1983) and to have a higher twinning rate than Scottish Blackface ewes when mated on improved pasture on a hill farm (Doney, Peart, Smith and Sim, 1983). Information is required on the performance of crossbred ewes derived from Friesland sires on other hill breeds and run in less favourable environments such as are common in the hills and uplands.

Gentle handling seems to elicit positive states in sheep. The study investigated whether spatial distance alters sheep responses to brushing and whether spatial distance is influenced by reactivity. Twenty Romane ewes were assessed in three sessions: in Sessions 1 and 3, one grid separated the test animal from pen mates, with no distance between them, and in Session 2 two grids separated the test animal from pen mates by a distance of about 1.7 m. Ewes had been genetically selected for low (R−) or high (R+) behavioural reactivity to social isolation. Body postures, head orientation, ear postures, closed and half-closed eyes, tail wagging and feeding behaviour, in addition to heart rate (HR) and HR variability, as the root mean square of successive differences (RMSSD), standard deviation of all normal-to-normal (NN) intervals (SDNN), RMSSD/SDNN ratio and ratio between low-frequency (LF) and high-frequency (HF) powers (LF/HF) were assessed. Data were analysed using generalized linear models and linear mixed models. Session, genetic line and phase (pre-, brushing and post-brushing) were considered fixed effects. Increased distance in Session 2 might not have influenced ewes’ responses. Fewer changes in ear postures were noted in Session 3 than 1 (P<0.01), suggesting that ewes were more relaxed in Session 3. The RMSSD/SDNN ratio was higher mainly during brushing in Sessions 1 and 3 (P<0.05), indicating that ewes were more relaxed during brushing, and at no distance between pen mates. However, spatial distance influenced R− and R+ ewes’ responses; R+ ewes performed more asymmetric ear postures in Session 2 than 1 and 3 (P<0.01), and in Session 3 than 1 (P<0.01), indicating that spatial distance had a negative effect on R+ ewes. Low reactive ewes spent less time on horizontal ear postures in Session 2 than 1 and 3 (P<0.01), and R+ ewes spent more time on horizontal postures in Session 1 than 3 (P<0.01). Curiously, R− ewes spent more time eating and ruminating in Session 3 than 1 (P<0.01), and in Session 2 than 1 and 3 (P<0.01), whereas R+ ewes ate and ruminated more in Session 1 than 3 (P<0.05). Higher HR was found among R− ewes in Session 2 than 1 and 3, and in Session 3 than 1 (P<0.01). High reactive ewes showed higher HR in Session 1 than 3 (P<0.01). The findings suggest that the social context might influence sheep responses to gentle handling, and the effects depend on their reactivity traits.

Learning and mental abilities of farm animals are important for their adaptation to new environments and could serve as an indicator for welfare and performance. This study assessed the learning ability and memory retention of broiler breeders through a T-maze test with a reward v. no reward set-up. Feed supplemented with or without meal worms served as a reward. Two trials were conducted with either parent stock (PS) breeders or pure line A (PL) breeders and with the same dietary treatment namely a control (C) group fed with standard commercial diets and a reduced balanced protein (RP) group fed with RP diets (25% reduction of CP and amino acids). To maintain similar target BW, the RP group received on average 10% more feed. A tonic immobility (TI) test was performed to estimate the fearfulness of PS breeders. Most breeders were capable of completing the T-maze tests, but the C group needed less time compared with the RP group when their own feed was given as a reward. However, when meal worms were provided as an extra incentive, the RP group completed the maze significantly faster than the C group. Compared to the C breeders, the RP breeders remained longer in a TI state, indicating a higher level of fearfulness. Long-term memory retention in the T-maze test was observed in both groups. It is concluded that the RP diet had no influences on the learning ability of the reward v. no reward discrimination test and its memory retention of broiler breeders. The increased amount of time the RP breeders needed to solve the test was probably due to a higher sense of fear. Furthermore, the RP diet enhanced the motivation of breeders to obtain an alternative feed such as meal worms.

In deterministic comparisons of breeding schemes it is necessary to take account of variance reduction due to selection. This can take place as multi-stage selection within generations and it takes place across generations when offspring of selected parents are selected. A standard way to deal with this is to set up selection index equations where the parameters are altered as a consequence of selection. It is shown that if the breeding schemes use a univariate or multivariate best linear unbiased prediction (BLUP) animal model for prediction of breeding values this procedure can be simplified. This is done by modelling the distribution of estimated breeding value (EBV) utilizing that changes in EBV of an individual are independent of selection. In the univariate case the variance reduction and the resulting genetic gain can be calculated from the selection intensities and the accuracies in the unselected population. An expression is given for the response in each generation when selection is started in a base population with complete pedigree. This shows that a limiting value is obtained within three to four generations. The asymptotic response for several traits is described in the case where selection is on multitrait BLUP.

Observations of the behaviour of confined sows provide information about how difficult it is for each individual to cope with the conditions in which it lives. Behaviour which has been described as occurring more frequently in confined sows than in sows with space to walk around includes stereotypies and apathetic behaviour. A stereotypy is a relatively invariate sequence of movements occurring so frequently in a particular context that it could not be considered to form part of one of the normal functional systems of the animal, feeding, body maintenance, reproduction, etc. (Broom 1983). The term apathetic behaviour has generally implied inactivity and lack of responsiveness. In this study, carried out at the Animal and Grassland Research Institute, the occurrence of stereotypies and the degree of responsiveness of stall-housed sows have been quantified.