Five randomized-block experiments were carried out over 2 years using British Friesian cows managed as three separate herds. The effects of offering cows different levels of concentrates, ranging from 0·8 to 7·2 kg/day, in addition to grass silage ad libitum during the winter period on reproductive performance was investigated. The effects of substituting 4 kg/day maize gluten, or 0·8 kg/day fish meal, for part or all of the standard concentrate were also examined.

Neither level of concentrates nor the inclusion of maize-gluten meal significantly affected reproductive performance even where milk production and quality was considerably influenced. The inclusion of fish meal improved conception rates to all services (0·64 v. 0·44; P < 0·05) and reduced the number of services required per conception (1·62 v. 2·31; P < 0·01).

Plasma urea levels were raised consistently by the feeding of fish meal and, with the exception of weeks 2 and 6 of lactation, by the feeding of higher levels of concentrates. From the 6th week of lactation levels of beta-hydroxybutyrate (BHB) in the blood were significantly higher in the group of cows receiving the highest level of concentrates. The BHB level at week 6 was correlated with the number of services required per conception.

A number of relationships between production factors and fertility are also presented.

A long-term experiment (first 24 weeks of lactation) with Danish Black and White cows and a short-term experiment with Jersey cows (experiment periods of 6 weeks) were carried out. In the long-term experiment, the effect of supplementing a normal dairy ration with 0·5 kg calcium (Ca) soap, 10 kg Ca-soap or 2 kg rolled barley was investigated in two herds, where silage was given ad libitum. The daily intakes of fatty acids in the diets were approximately 625, 1000, 1400 or 650 g respectively. Energy intake increased markedly by the supplementation, but not differently between soap or barley supplementation. The effect on milk production was not consistent in the two herds. In one herd, the soap supplement tended to increase milk fat yield (80 g/day) but not more than the barley supplementation which, in contrast to the fat supplementation, also increased milk protein yield. The effect of the fat was consistent over the first 6 months of lactation. In the other herd, only small differences in milk production were obtained with either supplements. In the short-term experiment carried out in mid lactation, a supplement of 0·8 kg Ca-soap increased daily intake of fatty acids from 730 to 1280 g per cow daily. Total food intake, milk and milk fat yield were not affected by the supplement but milk protein yield and live-weight gain were significantly reduced.

One hundred and sixty-two spring born steers comprising 54 Charolais × Friesian (CH), 54 Hereford × Friesian (HE) and 54 Friesians (FR) were reared together from shortly after birth until the end of their second grazing season at a mean age of 573 days. The animals were then blocked on weight within genotype, housed in a slatted shed and allocated to either a high (12·6 MJ metabolizable energy (ME) per kg) or a medium (10·4 MJ ME per kg) energy diet offered ad libitum until slaughter at one of three target carcass weights · light (260 kg (HE, FR and CH)), normal (300 kg (HE and FR) and 320 kg (CH)) or heavy (340 kg (HE and FR) and 380 kg (CH)) to give a 3 (breed type) · 2 (energy level) · 3 (slaughter weight) factorial arrangement during the finishing winter. The trial was repeated in 3 years consecutively.

CH were significantly heavier than HE at all times up to 18 months of age when they were 43 kg heavier, at which stage they were also 24 kg heavier than FR. CH grew significantly faster at pasture than HE in both seasons and faster than FR in the second season. HE had the best daily gain in the finishing period.

Overall slaughter weights per day of age, carcass weights per day of age and carcass weights of CH, HE and FR were 812, 771 and 761 (s.e. 9·2) g, 448, 418 and 405 (s.e. 4·8) g and 318. 299 and 298 (s.e. 2·2) kg, respectively. CH had significantly better killing-out proportions (lOg/kg) than HE which in turn were 10 g/kg better than FR. CH and FR had similar carcass length, carcass depth, leg length and leg widths and both were significantly larger than HE. CH had significantly larger longissimus dorsi areas than either HE or FR (80·9 v. 67·0 and 66·4 cm-); they also had significantly better conformation scores than HE which in turn were significantly better than FR.

Increasing the energy level during the finishing period increased daily gain by proportionately 0·52 (1089 v. 684 g/day), reduced slaughter age by 51 days (711 v. 762 days) and significantly increased killing-out proportion (551 v. 534 g/kg) and conformation score (4·86 v. 4·64). Offal as a proportion of empty live weight tended to be higher for FR than for HE or CH, the exception being the hide, which was significantly lower for FR.

The extra energy for walking compared with standing still (EW) (J/m per kg live weight) was measured in three Brahman cattle and two water buffalo. Ew was not affected by species or speed within the most comfortable range of speeds (V = 0·6 to 1·0 m/s) but over the whole range tested, Ew = 0·947F + 1·99 (r = 0·66, no. = 61) with average Ew = 2·1 (s.e. 0·06).

The extra energy cost of carrying loads while walking (Ec) (J/m per kg carried) was measured using two Brahman cattle, two water buffalo and a pony. Ec was independent of load (up to 70 kg) and speed but was generally lower when loads were placed over the animals' shoulders instead of on their backs. Average values for the cattle, buffaloes and the pony were 2·6, 4·2 and 3·3, respectively.

The efficiency of doing work defined as: work done/energy expended was measured in two Brahman cattle and two water buffalo and gave average values of 0·30 and 0·37 respectively for the two species. Efficiency was proportionately about 0·03 higher for animals wearing a collar than when wearing a single yoke but was unaffected by whether the animals wore single or double yokes, by the speed of travel, the size of the load or whether the load was steady or variable.

Along with appropriate values for the energetic efficiency of raising body weight when walking uphill, these data are used to derive a factorial equation for estimating the energy expenditure of animals working in the field.

Breeding data from 1543 artificial inseminations, performed on 763 purebred and crossbred zebu cattle reared on 73 small farms, in the Amazon basin of Peru from 1980 to 1986, were evaluated. Inseminations were performed during morning hours using Holstein or Brown Swiss frozen semen. The calving to first oestrus and calving to conception intervals, number of services per conception, intervals between services and conception rate were evaluated. A total of 64-4% of first services and 61-4% of conceptions occurred between the middle of the dry season and the middle of the rainy season. Farm effect proved to be the most important source of variation for all reproductive traits. Other important factors influencing the interval from parturition to first service were breed of cow, parity and season of service. Parity influenced the interval from parturition to conception while parity, time of oestrous detection and inseminator influenced conception rate. The long post-partum anoestrous interval was found to be the most important factor limiting reproductive efficiency on small farms involved in the artificial insemination programme. The reproductive performance of the crossbred cattle tended to be better than that of the purebred zebu cattle.

Intake, rumen digesta pool sizes, ruminal digestion rates, passage rates of liquid and particle pools and faecal particle-size distrubutions of grass, browse and lucerne diets were compared in ruminally fistulated moose, wapiti and cattle. For each diet, ruminal digestion rates (nylon bag technique) were similar for the three ruminants. Intakes, rumen digesta pool sizes and passage rates varied among species and higher rates were associated with passage of larger faecal particles. However, it was not possible to simply rank the three ruminants as representative grazers (cattle), browsers (moose) and mixed feeders (wapiti) since intakes, passage rates and rumen pool sizes interacted with diet and season. Contrary to expectation, digestible dry matter intakes of each species were not greatest for their respective typical diets.

Eleven sire breeds were evaluated in New Zealand from the performance of their calves at two sites using Aberdeen-Angus cows, and at a third site using Angus and Hereford cows. The experiment was carried out over 5 years, generating a total of 4519 calves by 161 different sires. There were seven recently imported sire breeds, Blonde d'Aquitaine, Charolais, Chianina, Limousin, Maine Anjou, Simmental (including strains from four countries) and South Devon, and four local breeds, Angus, Friesian, Hereford and Jersey. Overall, 92% of calves survived at birth and through to weaning, with a range from 86% for the Charolais sire breed to 96% for the Friesian and Jersey breeds. The proportion of calves (from cows aged 3 years and over) experiencing birth difficulty averaged 8·6% and ranged from 17·7% for the Charolais, 15·1% for the Chianina and 13·7% for the Maine Anjou, to 2·3% for the Hereford and 0·9% for the Jersey. Birth weights by sire breed had a range of 7·2 kg, proportionally 0·23 of the mean for the Hereford × Angus cross. The birth weights of calves by imported sire breds were greater than those of calves sired by local breeds by 4·7 kg. Sire breeds were ranked in approximately the same order for the weights of calves at weaning (5 months of age) and at 13 months of age. As a proportion of the mean for the Hereford × Angus crosses, there was a range due to sire breed of 0×17 for weaning weight and 013 for 13-month weight. As a group, the imported sire breeds had calves with 13-month weights 11·5 kg heavier than Hereford × Angus or 250kg heavier than straightbred Angus calves; proportionally these advantages in weight were 005 and 011, respectively. There was no evidence of any major interaction between sire breed and location. The heritability estimates ranged from 0·01 to 0·05 for calving difficulty and survival traits, from 0·13 to 0·33 for live weights and from 0·06 to 0·12 for pre-weaning live-weight gains. For gestation length the estimate was 0·48.

An experiment was carried out to compare sire breeds for carcass traits and to estimate heritabilities and phenotypic and genetic correlations. There were 1908 male cattle from 5 birth years. The sire breeds, each evaluated over three locations, were Blonde d'Aquitaine, Charolais, Chianina, Limousin, Maine Anjou, Simmental (four strains: Austrian, French (Pie Rouge), Swiss and West German) and South Devon (i.e. seven imported breeds) and Angus, Friesian, Hereford and Jersey (four local breeds), with a total of 161 sires represented. Each location contained Angus cows and additionally one location contained Hereford cows. Proportionally 0·72 of the cattle were slaughtered at about 20 months of age, whilst random samples from each of the first 4 years were retained for slaughter at about 31 months of age.

Sire breeds ranked similarly for live weight at 13 months of age and for pre-slaughter weights at both 20 and 31 months of age. Relative to the Hereford-cross, the seven imported breeds were proportionally 0·054 to 0·072 heavier at slaughter (depending on slaughter age) and they had 0-065 to 0·077 heavier carcasses. Dressing proportions for the Blonde d'Aquitaine, Chianina and Limousin sire breeds were higher by at least 0007 units than for the Hereford-cross. The seven imported breeds were all leaner and had larger areas of m. longissimus than the Hereford-cross cattle. Friesian-crosses also had high live or carcass weights although they were intermediate for fat depth.

The interaction of sire and dam breeds were only significant for fat depth (both slaughter ages) and for pre-slaughter and hot carcass weights (31-month slaughter age only). Interactions between sire breed and location were not important.

Heritability estimates on data adjusted to a slaughter age of 595 days were: pre-slaughter weight 0·29, hot carcass weight 0·28, dressing proportion 0·14, fat depth 0·03 and m. longissimus area 0·30. Corresponding values on cattle whose records were adjusted to an age of 935 days were 0·56, 0·44, 0·39, 0·37 and 0·29. These values were from cattle grazed on pasture, and were generally lower than those from America (from cattle offered high energy rations). Phenotypic correlations among all pairs of traits were positive, whilst genetic correlations were positive for all pairs except those involving fat depth (where standard errors were large).

Sheep were given diets containing 0, 30, 50 or 90 g/kg added free fatty acids from palm oil or from calcium soaps prepared from the same fatty acids in a three period switch-over design. Addition of free fatty acids to the diet enhanced metabolizable energy (ME) intake when added at 30 and 50 g/kg but not at 90 g/kg. On feeding 90 g/kg free fatty acids, rumen volatile fatty acid levels decreased and acid-detergent fibre and protein digestion was reduced. Calcium soaps of fatty acids enhanced ME intake at all levels added and had no effect on rumen fermentation. Addition of both free fatty acids and calcium soaps of fatty acids enhanced apparent digestibility of total fatty acids and of all fatty acids except stearic acid. The ME of free fatty acids added at 30 g/kg was 35·56 MJ/g and of calcium soaps of palm oil was approximately 33·05 MJ/g.

Faecal egg counts, haematocrits, erythrocyte potassium contents and serum iron concentrations were determined in 1005, 3- to 5-month-old Merino lambs infected with a single dose of 11 000 Haemonchus contortus larvae. Live-weight gain and wool growth also were recorded. Lambs were infected in six different groups over a 3-year period. When infections were terminated after 5 weeks, faecal egg counts in the six infected groups had reached a peak of 5170 to 20 339 eggs per g (average 12 909), haematocrits had declined to between 196 and 309 ml/1 (average 233), erythrocyte potassium contents had risen to between 16·7 and 37·5 mequiv. per 1 (average 31·5) and serum iron concentrations, in some cases following an erratic course, had dropped to between 0·512 and 1·546 mg/1 (average 0·946).

Of the three haematological parameters, haematocrit correlated best with faecal egg count (r = 0·7 in four of six infected groups). However, in two groups with low faecal egg counts this correlation was much lower (r = 0·3). Erythrocyte potassium concentration and serum iron concentration significantly correlated with variability of haematocrit not accounted for by faecal egg count, suggesting that both erythropoiesis and iron availability influence the degree of anaemia.

The effect of H. contortus infection on productivity of lambs was best predicted by haematocrits: for each further 0·01 proportional decrease in haematocrit, a 0·03 reduction of live-weight gain over a 9-week post-infection period, a 0·007 reduction in clean wool growth and a 0·004 reduction in fibre diameter over a 4- to 9-week period were observed. Some evidence was obtained indicating a tolerance level of anaemia at approximately 280 ml/1 packed cell volume.

Two trials were undertaken to investigate the effects of treating seasonally anoestrous ewes with melatonin implants on date of first oestrus and other aspects of reproductive performance.

Trial 1 involved a total of 368 Mule ewes and 79 Scottish Blackface ewes on five farms, approximately half of which were treated with a single subcutaneous implant of melatonin (Regulin®), containing 18 mg melatonin, between 23 July and 6 August 1986 and the remainder acted as untreated controls. Treatment had no significant effect on the date of first oestrus or conception rate in Mule ewes, although it increased the number of Scottish Blackface ewes mating (92% v. 73%) and the number of mated ewes conceiving (69% v. 54%) in a 5-week mating period, resulting in significantly more treated ewes lambing (63% v. 37%; P < 0·01). Litter size was higher in 4/5 flocks, although this only reached statistical significance in one Mule flock and the Scottish Blackface flock.

A total of 2116 ewes from 17 commercial flocks were used in trial 2, approximately half of which were Suffolk/Suffolk-cross ewes and the remainder Mule/Mule-cross ewes. Implantation with melatonin occurred between 22 June and 24 July 1987. Flocks with over 100 ewes were divided into three equal-sized groups and treated with either 18 mg melatonin (one implant of Regulin, 36 mg melatonin (two implants of Regulin given at the same time) or acted as untreated controls. Flocks with less than 100 ewes contained only the 18 mg melatonin and untreated control groups. Treatment with melatonin significantly advanced the date of first oestrus in most flocks of both breeds (P < 0·05) but the magnitude of this effect was variable. Significant (P < 0·05 at least) increases in ‘potential’ (from scanning) mean litter size (+0·13 to +0·18) and actual mean litter size (+0·11 to +0·14) resulting from treatment with melatonin were apparent in ewes of both breeds when the data were pooled across all flocks, but only in 4/17 of the individual flocks.

These results indicate that treatment with melatonin implants may be a simple and effective way of advancing the breeding season and enhancing litter size of early lambing flocks under commercial farming conditions in the United Kingdom, but treatment must be given >60 days before the start of the natural breeding season for benefits in date of first oestrus to be manifest.

The effects of an increase of rumen fill obtained with polystyrene cubes, and able to stimulate mechanically the rumen wall were investigated on alimentary behaviour and reticulo-rumen motility in sheep. The introduction through a rumen cannula of a volume of polystyrene cubes equal to one-quarter of the ruminal pool size depressed the daily intake of both low-quality cocksfoot hay and good-quality lucerne hay (P < 0·05). Surprisingly, the time spent ruminating was slightly increased and the frequency of contractions during rumination was significantly increased (P < 0·05). In addition, in the sheep fed enterally with a liquid into the rumen, either the mechanical stimulation of the rumen dorsal wall or the introduction of hay (200 g) into the rumen, induced a rumination molility pattern. It is concluded that the intensity of mechanical stimulation of the dorsal sac of the rumen by food particles, which depends upon rumen fill, reduces the time spent eating to increase the duration and intensity of rumination.

The effects of sex (wethers v. ewes), diet (chopped lucerne hay v. lucerne-barley pellets) and cimaterol on energy utilization by Suffolk cross lambs were determined by comparative slaughter. Quadratic regression of energy retention (RE) on metabolizable energy intake (MEI) enabled estimation of maintenance energy requirements (Em), efficiencies of gain (ktotal) and maximum rates of gain (REMAX). Regressions using RE in fat and protein v. MEI yielded analogous parameters for fat and protein deposition (Em fat, kfat, REMAX fat and Emprotcin, kprolein, REMAXprotcin respectively). Em was lower in wethers than ewes (455 v. 510 kJ/kg M0·75 per day respectively), but was unaffected by diet or cimaterol. Sex and cimaterol did not affect ktotai. which was higher in lambs given pellets compared with lambs given hay (0·417 v. 0·224 respectively). Similarly, REMAX was higher in lambs given pellets than in lambs given hay (326 v. 114 kJ/kg 0·75 per day respectively). None of the groups differed significantly in the parameters of fat deposition, which averaged 480 kJ/kg 0·75 per day for Em fal, 0·224 for ktat, and 250 kJ/kg M0·75 per day for REMAX, fat- Em.protein was lower in wethers than in ewes (466 v. 569 kJ/kg 0·075 per day, respectively), and was further reduced by cimaterol (418 and 507 kJ/kg 0·75 per day for wethers and ewes respectively). Estimates of kprotcin were higher in wethers than in ewes (0·091 v. 0·064 respectively), and were increased by cimaterol (0·115 and 0·089 for wethers and ewes respectively). Similarly REMAX protein was higher in wethers than in ewes (47 v. 37 kJ/kg 0·75 per day respectively), and was increased by cimaterol (58 and 48 kJ/kg 0·75 per day for wethers and ewes respectively). The repartitioning action of cimaterol was additive with effects of diet, intake and sex.

Duroc and halothane negative British Landrace boars and gilts were performance tested on ad libitum or restricted feeding regimes, with like-sexed non-littermate groups of one, two, three or four pigs per pen. There was a total of 320 pigs with 20 litter groups per breed with four boars and four gilts per litter group. Within each feeding regime, a boar and a gilt from each litter were tested on one of two diets in 1986, for each of the four combinations, and pigs were tested similarly for two other diets in 1987. Carcass composition was determined by half-carcass dissection of 160 pigs allocated between treatments.

There was a breed × sex interaction for growth and performance traits for pigs fed ad libitum. Duroc boars were faster growing and more efficient than Landrace boars, but Duroc gilts grew more slowly and were less efficient than Landrace gilts. On restricted feeding, Duroc pigs were more efficient than Landrace pigs.

At constant slaughter weight, Duroc pigs had less subcutaneous fat but more intermuscular fat. Although they had less separable fat in the carcass, Duroc pigs were not leaner as weights of bone, skin, head, feet and tail were heavier than for Landrace pigs.

Group penning and group feeding of pigs may have enhanced competition effects resulting in positive genetic and phenotypic correlations between growth rate and backfat depths on both feeding regimes.

The positive genetic correlation between growth rate and fat deposition resulted in a negative genetic correlation between growth rate and carcass lean content and a lower genetic correlation with lean tissue growth rate than in other studies.

Six diets based on maize and soya-bean meal were prepared. The basal diet had a crude protein (CP) concentration of 171 g/kg. The same ingredients, together with maize starch, were used to give a diet with CP 131 g/kg. This diet was supplemented with all (positive control) or with three of the four amino acids lysine, threonine, tryptophan and methionine. Each diet was given at two rates of intake. From the results, the optimum ratio between these four amino acids at different planes of intake was calculated. Amino acid digestibility in the basal diet was measured at three intakes, using pigs fitted with T cannulas at the terminal ileum.

The results showed that the optimum ratios between the four amino acids (expressed in terms of digestible amino acids) were not affected by the rate of food intake. The optimum ratio between the four amino acids (i.e. when they are equally limiting) was lysine 1·00, methionine + cystine 0-61, threonine 0·64 and tryptophan 0·20. Digestibility was not affected by the level of intake.

Two hundred and thirty-nine pigs reared at the Meat and Livestock Commission's Stotfold Pig Development Unit and derived from the four major breeding companies in the UK were slaughtered at 63 kg live weight in an experiment which examined the effect of genotype (Meat-line or White-line), pre-slaughter transport time (1 or 4 h) and lairage time (2 or 21 h) on carcass and meat quality. The pre-slaughter handling was chosen to simulate good commercial procedures and cover the range of transport and lairage times probably experienced by a large proportion of British slaughter pigs. Meatline pigs had higher killing-out proportions and heavier carcasses, with increased cross-sectional area of the m. longissimus dorsi. Backfat thickness was similar in the two genotypes. White-line pigs had heavier livers and produced meat which potentially had a lower incidence of PSE. Longer transport time increased live-weight loss. It reduced carcass yield in the White-line but not in the Meat-line pigs. Transport had no major effects on meat quality. Longer lairage, during which the pigs were fed in compliance with the law, resulted in reduced carcass yield but increased liver weight and allowed some repletion of liver glycogen. It also reduced ultimate pH values in the m. semimembranosus and m. adductor. There were no important or consistent differences in the way pigs of the two genotypes responded to pre-slaughter handling.

Infectious atrophic rhinitis is a disease of the upper respiratory tract of pigs, characterized in the live animal by deformation of the snout and conchal atrophy. However, the severity of the disease in pigs on commercial units is highly variable and air quality may be implicated as a significant factor in addition to the recognized pathogens. In this study the aerial environment was monitored in 49 pig buildings on 12 commercial farrowing-finishing units. A total of 1117 pigs from the 12 farms were examined individually at commercial slaughter weight to quantify the severity of conchal atrophy, using snout scoring and morphometric techniques.

A number of significant relationships were shown between environmental variables in the farrowing house and the severity of conchal atrophy. Mean snout score (MSS) and the percentage of snouts from each herd sample with a score of three or more (SS3) were correlated with total bacterial counts (r = 0·78 (P < 0·01) and 0-83 (P < 0·01) respectively), counts of 10 [mi to >15 urn particles (r = 0·67 (P <0·05), 0·73 (P <0·05)) and concentrations of gravimetric dust (r = 0·65 (P <0·05), 0·64 (P <0·05)). Concentrations of ammonia were correlated with SS3 (r = 0·68 (P <0·05)).

Dust in the first-stage weaner houses was again a significant component of the aerial environment associated with the severity of the disease. MSS and SS3 were correlated with counts of 10 urn to >15 μm particles (r = 0·66 (P <0·05), 0·68 (P <0·05)), concentrations of respirable dust (r = 0·67 (P <0·05), 0·63 (P <0·05)), total dust (r = 0·75 (P <0·05), 0·87 (P <0·001)), and gravimetric dust (r = 0·83 (P <0·01), 0·88 (P <0·001)). The results support the theory that the mass or number of particles present as inspirable aerosols, and the presence of large numbers of viable bacteria may compromise the local defence mechanism of the upper respiratory tract in the pig and facilitate colonization by Bordetella bronchiseptica and Pasteurella multocida. Saturation deficit in the second-stage weaner houses was correlated with both mean morphometric index and SS3 (r = 0·860 (P <0·01) and 0·683 (P <0·05) respectively), and volumetric stocking density in the finishing houses was correlated with both MSS and SS3 (r = -0·84 (P <0·01), -0·64 (P <0·05)). It is hypothesized that the severity of the disease may be lessened by reducing the concentrations of dust, microbes and ammonia which may play a significant role in the development of the disease.

The proportions of abdominal fat and total body lipid and protein were measured up to 30 weeks in males and 21 weeks in females from lines of lean and fat broiler chickens given diets of different protein content. There was a constant relationship between the proportions of abdominal fat and body lipid independent of line, diet or age. Data on males showed effects of line and diet on body fatness at all ages up to 30 weeks. In females, line and diet had effects on body fatness during early growth but little effect on composition at 21 weeks. Plasma very low density lipoprotein concentration was higher in the fat line in both sexes at all ages. Egg production over the first few weeks of the laying period was much higher in lean line hens.

A study was carried out on data collected between 1970 and 1979 on the crossbreeding of cattle in Vom using British Friesian, Brown Swiss and Jersey bulls. Only crossbreeding involving Friesian bulls was successful. There were progressive increases in lactation yield, yield per day of lactation length, lactation length, daily fat yield, birth weight and calving interval in the grades with increases in the Friesian contribution. The daily fat concentration however decreased with the increase in Friesian proportion. Most of the genotypes namely, pure White Fulani, 0·5 Friesian: 0·5 White Fulani; 0·75 Friesian: 0·25 White Fulani, 0·875 Friesian: 0·125 White Fulani and pure Friesian calved regularly each year. Phenotype correlations between lactation length and yield for most of the genotypes were high, positive and significant.

The response of pigs to supplemental biotin (500 μg/kg diet) was studied in a growth trial from 15 to 88 kg live weight. Food: gain ratio was significantly improved during the grower phase and there was a tendency for improvement in the starter and finisher phases. There was also a tendency towards improved carcass grading.