About 350 single- and 250 twin-born female Ayrshire cattle were compared on the same feeding regime in respect of 12 linear body measurements at 3-monthly intervals up to 36 mo of age, and some two-thirds of them up to 48 mo. The twins were purchased from a wide variety of farms, and it is unlikely that their dams were significantly better fed, in pregnancy, than the dams of single calves.

The effects of month and year of birth and age at first calving (including some pregnancy and lactation effects) were estimated by least-squares procedures. The trends of the differences between single and twin-born animals were analysed as percentages of current and of mature size. Earliness of maturing had no apparent effect. For the traits of height and girth, twin-born animals were smaller than single-born by nearly 2 % of mature size (3 % of current size) at 3 mo of age and for the other traits the difference was around 1 %. By 12 mo the differences were generally about half their initial value and remained at this level, except for head width where the difference declined to zero around 2 years of age.

It is concluded that twin-, compared to single-born, cattle are subject to a small degree of permanent stunting in most linear measurements.

Two experiments were carried out to compare the performance and carcass quality of pigs given diets based on barley, wheat or maize meal, and another two experiments comparing these cereals, flaked maize and sorghum. In general, differences in the utilization of feed for live-weight gain could be related to differences in the digestible energy content of the cereals used in the diet, although in some experiments pigs behaved atypically on individual diets. Flaked maize was consistently inferior to the other cereals in the efficiency of conversion of its digestible energy, possibly because of its poorer amino acid balance and its low levels of lysine and tryptophan in relation to energy. Differences between experiments in the performance of pigs fed on the various diets are also discussed. Differences between treatments in killing-out percentage and predicted lean percentage were small, and carcasses of pigs from all treatments were acceptable for bacon curing.

The results of studies into penial, scrotal and testicular development of Icelandic male lambs indicate relatively early attainment of physiological puberty. This stage of sexual maturity is generally reached by 4 months of age, with marked variation in both puberal age and body weight. Testicular and epididymal weights were more closely associated with body and carcass weights than with age of the lamb. It is a common practice to use Icelandic male lambs for breeding at 7 months of age.

With our increased knowledge of genetics and our ability to control breeding populations of farm animals we are now in a position to select for optimum size if we can define it. A consideration of size in relation to nutritional efficiency therefore becomes relevant. (I confine myself to nutritional efficiency since this was my remit, but of course there are many non-nutritional aspects of productivity which also may be related to size, e.g. larger animals need less labour or housing per unit of production; smaller animals may yield more suitable carcasses for some markets, and these may indeed be more important economically than nutritional efficiency.) Nutritional efficiency will be considered in relation to energy use, since energy is normally the limiting nutrient, and the concentration of the other nutrients, proteins, minerals and vitamins can be varied by adding supplements to the diet.

Vitamin A (all-trans retinol) is an important antioxidant whose role in embryo development in vitro and in vivo is well established. Oxidative stress is a major cause of defective embryo development. This study evaluated the effects of all-trans retinol supplementation to maturation and embryo culture media under different gaseous environments on the development of ovine oocytes and embryos in vitro. The percentages of cleavage, morula and blastocyst, total cell count and comet assay were taken as indicators of developmental competence of embryos. In experiments I and II, all-trans retinol at concentrations of 0, 2, 4, 6, 8 and 10 μM were supplemented to the oocyte maturation medium and cultured in an environment of 5% or 20% O2 respectively. All-trans retinol supplementation (6 μM) to the maturation medium at 5% O2 levels significantly increased blastocyst yield and total cell number (P < 0.05). Maturation of oocytes in a 20% O2 environment bettered cleavage rates in the 6 μM supplemented group compared with the control group (P < 0.05). In experiments III and IV, all-trans retinol, at the aforesaid concentrations was supplemented to embryo culture media under a 5% or 20% O2 environment, respectively. All-trans retinol supplementation to the embryo culture medium at 5% O2 levels did not yield any significant result whereas the culture at 20% O2 levels gave significantly higher blastocyst yield in the 6 μM supplemented group compared with the control group (P < 0.01).

The profitability of dual-purpose breeding farms can be increased through genetic improvement of carcass traits. To develop a genetic evaluation of carcass traits of young bulls, breed-specific genetic parameters were estimated in three French dual-purpose breeds. Genetic correlations between these traits and veal calf, type and milk production traits were also estimated. Slaughter performances of 156 226 Montbeliarde, 160 361 Normande and 8691 Simmental young bulls were analyzed with a multitrait animal model. In the three breeds, heritabilities were moderate for carcass weight (0.12 to 0.19±0.01 to 0.04) and carcass conformation (0.21 to 0.26±0.01 to 0.04) and slightly lower for age at slaughter (0.08 to 0.17±0.01 to 0.03). For all three breeds, genetic correlations between carcass weight and carcass conformation were moderate and favorable (0.30 to 0.52±0.03 to 0.13). They were strong and favorable (−0.49 to −0.71±0.05 to 0.15) between carcass weight and age at slaughter. Between age at slaughter and carcass conformation, they were low and unfavorable to moderate and favorable (−0.25 to 0.10±0.06 to 0.18). Heavier young bulls tend to be better conformed and slaughtered earlier. Genetic correlations between corresponding young bulls and veal production traits were moderate and favorable (0.32 to 0.70±0.03 to 0.09), implying that selecting sires for veal calf production leads to select sires producing better young bulls. Genetic correlations between young bull carcass weight and cow size were moderately favorable (0.22 to 0.45±0.04 to 0.10). Young bull carcass conformation had moderate and favorable genetic correlations (0.11 to 0.24±0.04 to 0.10) with cow width but moderate and unfavorable genetic correlations (−0.21 to −0.36±0.03 to 0.08) with cow height. Taller cows tended to produce heavier young bulls and thinner cows to produce less conformed ones. Genetic correlations between carcass traits of young bulls and cow muscularity traits were low to moderate and favorable. Finally, genetic correlations between carcass traits of young bulls and milk production traits were low and unfavorable to moderate and favorable. These results indicate the existence for all three breeds of genetic variability for the genetic improvement of carcass traits of young bulls as well as favorable genetic correlations for their simultaneous selection and no strong unfavorable correlation with milk production traits.

Two groups of ewes in good body condition at the start of the breeding season were given either sufficient feed to maintain their body weight or 500 g/kg of a maintenance ration such that they showed a continuous fall in body weight. On three separate occasions after introducing the nutritional regimens, all ewes were challenged on day 12 of the oestrous cycle with 150 μg luteinizing hormone-releasing hormone. Prolonged chronic undernutrition resulted in a significant increase in luteinizing hormone release in response to luteinizing hormone-releasing hormone injection (P < 0·05), whereas the mean pre-injection luteinizing hormone concentrations were significantly reduced by undernutrition (P < 0·01).

An experiment was conducted to evaluate the feeding characteristics and the productive responses of lamb diets containing increasing levels of dried brewers' grains (DBG). Five groups of six 70-day-old Bergamasca lambs were housed in individual pens and given ad libitum for 9 weeks pelleted diets containing 200 g/kg of concentrate and 800 g/kg of a mixture of DBG and lucerne hay in the ratios of 0:80 (DBG0), 20:60 (DBG20), 40:40 (DBG40) 60:20 (DBG60) and 80:0 (DBG80). During the last 12 days of the experimental period, a digestibility trial was carried out for each diet. After this, all the lambs were slaughtered and the composition of the empty body weight was determined. The initial composition of the empty body was estimated from the composition of a sixth group of lambs slaughtered at the beginning of the trial.

The apparent digestibility of dry matter (DM), organic matter, crude protein, ether extract, neutral-detergent fibre and energy increased with the proportion of DBG. The daily DM intake relative to metabolic body weight (M0·75) diminished significantly with the increasing proportion of DBG in the diet, from 127 g/kg M0·75 for diet DBG0 to 83 g/kg M0·75 for diet DBG60. The daily live-weight gain and food DM conversion efficiency were highest with the intermediate diets (414 g/day with diet DBG40 and 240 g/kg DM with DBG60), showing a quadratic trend, an indication of a positive interaction between DBG and lucerne hay. The fat content of the live-weight gain was particularly high in the lambs given the diet with the highest proportion of DBG. It was concluded that DBG may be profitably used in growing-fattening diets for lambs in a proportion not exceeding about 400 g/kg DM.

Studies on microbial biohydrogenation of fatty acids in the rumen are of importance as this process lowers the availability of nutritionally beneficial unsaturated fatty acids for incorporation into meat and milk but also might result in the accumulation of biologically active intermediates. The impact was studied of adsorption of 22:6n-3 (DHA) to particulate material on its disappearance during 24 h in vitro batch incubations with rumen inoculum. Four adsorbants were used in two doses (1 and 5 mg/ml of mucin, gum arabic, bentonite or silicic acid). In addition, the distribution of 22:6n-3 in the pellet and supernatant of diluted rumen fluid was measured. Bentonite and silicic acid did not alter the distribution of 22:6n-3 between pellet and supernatant nor increased the disappearance of 22:6n-3 during the incubation. Both mucin and gum arabic increased the recovery of 22:6n-3 in the supernatant, indicating that these compounds lowered the adsorption of the fatty acid to ruminal particles. This was associated with an increased disappearance of 22:6n-3, when initial 22:6n-3 was 0.06 or 0.10 mg/ml, and an increased formation of 22:0, when initial 22:6n-3 was 0.02 mg/ml, during the 24 h batch culture experiment. Addition of gum arabic to pure cultures of Butyrivibrio fibrisolvens or Butyrivibrio proteoclasticus did not negate the inhibitory effect of 22:6n-3 on growth. As both mucin and gum arabic provide fermentable substrate for ruminal bacteria, an additional experiment was performed in which mucin and gum arabic were replaced by equal amounts of starch, cellulose or xylan. No differences in disappearance of 22:6n-3 were observed, suggesting that the stimulatory effect of mucin and gum arabic on disappearance of 22:6n-3 most probably is not due to provision of an alternative site of adsorption but related to stimulation of bacterial growth. A relatively high proportion of 22:6n-3 can be reduced to 22:0 provided the initial concentration is low.

To estimate the nutritional requirements of hair sheep, knowledge about the animal’s weight and its relationships with growth performances is essential. A study was carried with the objective to establish the relationships between BW, fasting BW (FBW), empty BW (EBW), average daily gain (ADG) and empty BW gain (EBWG) for hair sheep in growing and finishing phases in Brazilian conditions. Databases were obtained from 32 studies, for a total of 1145 observations; there were 3 sex classes (non-castrated male, castrated male and female) and 2 feeding systems (pasture and feedlot). The most representative breeds in the database were Santa Ines (n = 473), Morada Nova (n = 70) and Brazilian Somali (n = 47). The other animals in the database were crossbreeds (n = 555). The FBW (kg), EBW and EBWG (kg/day) were estimated according to linear regression. A random coefficient model was adopted, considering the study as a random effect and including the possibility of covariance between the slope and the intercept. The coefficients obtained from the linear regression of the FBW against the BW, EBW against the FBW and EBWG against the ADG did not differ between sex class (P > 0.05) and genotype (P > 0.05). The equations generated to estimate FBW from the BW, EBW from the FBW and EBWG from the ADG are as follows: FBW = −0.5470 (±0.2025) + 0.9313(±0.019) × BW, EBW = −1.4944 (±0.3639) + 0.8816 (±0.018) × FBW and EBWG = 0.906 (±0.019) × ADG, respectively. The low mean squared error values found in the cross-validation confirmed the reliability of these equations. Considering a sheep with a BW of 30 kg and a 100 g ADG, the estimated FBW, EBW and EBWG calculated using the generated equations are 27, 22.65 and 0.090 kg, respectively. In conclusion, the generated equations can be used in growing hair sheep. The validation procedure applied to the generated equations showed that its use for hair sheep seems to be appropriate.

The present study was designed to measure the use of various, simultaneously available resources in a complex housing environment in juvenile blue foxes. Twelve blue fox sibling (male–female) pairs were housed in two-section experimental cages from the age of 8 weeks until the age of 7 months (from June to December). Each experimental cage was furnished with two platforms, a nest box, a sand box and a wooden block. This housing set-up provided the foxes with social contact, and an opportunity for oral manipulation, scratching and nesting, as well as the choice of staying on a solid floor material or on an elevated location. The foxes’ behaviour was recorded at three time points during autumn (September, November and December). The foxes used all available resources. The most utilised resource was the nest box, possibly because it could be utilised in several ways (as a shelter, an elevated location, an object for scratching and for oral manipulation). The foxes also stayed more in the cage section containing the nest box than in the cage section containing a sand box. The foxes rested much on the cage floor, but they also used the interior of the nest box and elevated locations for resting. Social contact often occurred during resting. Thus, the nest box and elevated location, in conjunction with social contact seem to be valuable while resting. While active, the foxes utilised the cage floor and roof of the nest box instead of the platforms. Scratching, digging and an interaction with the wooden block were seldom observed. Activity occurred mainly on the ‘empty’ cage area. In conclusion, all studied resources provided blue foxes with a distinct value, as they all were used in the complex housing environment. The nest box is used most and for most variable behaviours.

Mature Angus (A), Hereford (H) and Simmental (S) cows (16 each) that had been randomly assigned and fed a maize silage-based diet at different levels of intake during lactation were selected.

Lean and fat A, H and S cows were fed the maize silage-based diet individually to provide metabolizable energy (ME) intakes of 542, 506; 476, 437; and 624, 597 kj/kg0.75 per day respectively for 84 days. Daily weight gains of lean cows were greater than those of fat cows (0·40 v. 0·11 kg/day) even though daily ME intakes were less (55·2 v. 62·4 MJ/day). Theoretical estimates of ME requirements for maintenance were less for lean than for fat cows, and maintenance of A and H cows tended to be less than those of S cows.

These results suggest that cow maintenance requirements increased in association with fatness that resulted from the previously imposed nutritional regimes and tended to differ among cow breeds.

Ruminants remain productive during the energy insufficiency of late pregnancy or early lactation by evoking metabolic adaptations sparing available energy and nutrients (e.g. higher metabolic efficiency and induction of insulin resistance). A deficit in central leptin signaling triggers these adaptations in rodents but whether it does in ruminants remains unclear. To address this issue, five mature ewes were implanted with intracerebroventricular (ICV) cannula in the third ventricle. They were used in two experiments with an ovine leptin antagonist (OLA) when well-conditioned (average body condition score of 3.7 on a 5 point scale). The first experiment tested the ability of OLA to antagonize leptin under in vivo conditions. Ewes received continuous ICV infusion of artificial cerebrospinal fluid (aCSF), ovine leptin (4 µg/h) or the combination of ovine leptin (4 µg/h) and its mutant version OLA (40 µg/h) for 48 h. Dry matter intake (DMI) was measured every day and blood samples were collected on the last day of infusion. ICV infusion of leptin reduced DMI by 24% (P<0.05), and this effect was completely abolished by OLA co-infusion. A second experiment tested whether a reduction in endogenous leptin signaling in the brain triggers metabolic adaptations. This involved continuous ICV infusions of aCSF or OLA alone (40 µg/h) for 4 consecutive days. The infusion of OLA did not alter voluntary DMI over the treatment period or on any individual day. OLA did not affect plasma variables indicative of insulin action (glucose, non-esterified fatty acids, insulin and the disposition of plasma glucose during an insulin tolerance test) or plasma cortisol, but tended to reduce plasma triiodothyronine and thyroxine (P<0.07). Overall, these data show that a reduction of central leptin signaling has little impact on insulin action in well-conditioned mature sheep. They also raise the possibility that reduced central leptin signaling plays a role in controlling thyroid hormone production.

Sequential feeding (SF) consists of splitting energy (E) and protein/calcium (P) fractions temporally, improving the feed conversion ratio (FCR) of hens compared with a continuous distribution during the day. In a previous study, the E fraction (with a low level of protein) was provided in the morning, whereas the P fraction (with low level of energy) was given in the afternoon. However, there is no clear evidence that a requirement in energy or proteins is connected to these distribution sequences, whereas the requirement for calcium is known to be required in the afternoon. To evaluate the effects on performances of the modulation of energy and protein supplies in SF, five different sequential treatments were offered: E0P0/E0P0; E+P+/E−P−; E+P−/E−P+; E0P+/E0P− and E+P0/E−P0 where E+ represents a high energy level, E0 a moderate one and E− a low one (with the same meaning for P regarding protein supply). Afternoon fractions were provided with particulate calcium. A total of 168 Hendrix hens were housed in individual cages from 20 to 39 weeks of age in two environmentally contrasted rooms. Feed intake in the morning and afternoon fractions, egg production, egg weight, BW and weight of digestive organs were recorded. No diet effect was observed concerning feed intake, egg production and BW. These results suggested that hens are not able to fit their feed intake on energy or protein level of fractions within half-day duration, whereas at the day scale same protein and energy intakes were observed. Moreover, the time of nutrient distribution in feeding did not seem to have an impact on birds’ performances. These studies have also demonstrated that, despite strong environmental pressure, the hens with SF had attenuated performance but continue to produce eggs.

Although the use of local breeds is recommended by organic regulations, breed comparisons performed under organic production conditions with similar production intensities are scarce. Therefore, we compared data of local and widely used Holstein dairy cattle breeds from 2011 to 2015 regarding production, fertility and health from German and Swedish organic farms with similar management intensities within country. In Germany, the energy-corrected total milk yield tended to be lower in the local breed Original Angler Cattle (AAZ, 5193 kg) compared to the modern German Holstein Friesian breed (HO, 5620 kg), but AAZ showed higher milk fat and protein contents (AAZ v. HO: 5.09% v. 4.18% and 3.61% v. 3.31%, respectively). In Sweden, the widely used modern Swedish Holstein (SH) breed had the highest milk yield (9209 kg, fat: 4.10%, protein: 3.31%), while the local Swedish Polled (SKB) showed highest milk yield, fat and protein contents (6169 kg, 4.47%, 3.50%, respectively), followed by the local breed Swedish Red (SRB, 8283 kg, 4.33%, 3.46%, respectively). With regard to fertility characteristics, the German breeds showed no differences, but AAZ tended to have less days open compared to HO (−17 days). In Sweden, breeds did not differ with regard to calving interval, but both local breeds showed a lower number of days open (−10.4 in SRB and −24.1 in SKB compared to SH), and SKB needed fewer inseminations until conception (−0.5 inseminations) compared to SH. Proportion of test day records with a somatic cell count content of ≥100 000 cells per ml milk did not reveal breed differences in any of the two countries. German breeds did not differ regarding the proportion of cows with veterinary treatments. In Sweden, SRB showed the lowest proportion of cows with general veterinary treatment as well as specific treatment due to udder problems (22.8 ± 6.42 and 8.05 ± 2.18, respectively), but the local breed SKB did not differ from SH in either of the two traits. In Sweden, we found no breed differences regarding veterinary treatments due to fertility problems or diagnosis of claw or leg problems during claw trimming. Our results indicate a stronger expression of the antagonism between production and functional traits with increasing production intensity. Future breed comparisons, therefore, need to consider different production intensities within organic farming in order to derive practical recommendations as to how to implement European organic regulations with regard to a suitable choice of breeds.

Despite the economic importance of beef cattle production in Brazil, female reproductive performance, which is strongly associated with production efficiency, is not included in the selection index of most breeding programmes due to low heritability and difficulty in measure. The body condition score (BCS) could be used as an indicator of these traits. However, so far little is known about the feasibility of using BCS as a selection tool for reproductive performance in beef cattle. In this study, we investigated the sources of variation in the BCS of Nellore beef cows, quantified its association with reproductive and maternal traits and estimated its heritability. BCS was analysed using a logistic model that included the following effects: contemporary group at weaning, cow weight and hip height, calving order, reconception together with the weight and scores of conformation and early finishing assigned to calves at weaning. In the genetic analysis, variance components of BCS were estimated through Bayesian inference by fitting an animal model that also included the aforementioned effects. The results showed that BCS was significantly associated with all of the reproductive and maternal variables analysed. The estimated posterior mean of heritability of BCS was 0.24 (highest posterior density interval at 95%: 0.093 to 0.385), indicating an involvement of additive gene action in its determination. The present findings show that BCS can be used as a selection criterion for Nellore females.

Dirty udders and teats result in a higher workload in terms of cleaning before milking and may constitute a risk for udder health. The aim of this prevalence study on 23 farms with very low within-farm variation in cubicle measures and other cubicle characteristics was to identify potentially influencing housing and management factors concerning teat and teat tip soiling. Information about udder soiling, housing and management was collected through direct recording and farmers’ interviews. Height at withers, shoulder width and diagonal body length were measured in 79% to 100% of the cows in each herd. On the basis of the 25% largest animals, compliance with recommendations for cubicle measures was calculated, which was generally rather low. Stepwise regression was used to find predictors for the percentage of dirty teats and of dirty teat tips. The final model on dirty teats explained 58.5% of the variance and contained four factors (F = 6.34, P = 0.0023). Less soiled teats were found on farms that conducted teat dipping after milking (t = −3.21, P = 0.0048), had increased daily cubicle maintenance time (t = −2.58, P = 0.0187), deep-bedded cubicles (t = −2.42, P = 0.0265) and decreasing compliance concerning cubicle length (t = 2.33, P = 0.0317). The final model on teat tip soiling explained 46.0% of the variance and contained three factors (F = 5.39, P = 0.0075). Less soiled teat tips were associated with increasing height of bedding material (t = −2.89, P = 0.0094) and decreasing compliance concerning resting length (t = 2.12, P = 0.0470). Difficult to explain was the association found between increased passage soiling and decreased teat tip dirtiness (t = −1.86, P = 0.0790). Thus, even under relatively restrictive cubicle conditions, a certain increase in teat and teat tip soiling was found with increasing cubicle length. However, at the same time, measures relating to good management may positively affect teat and teat tip cleanliness. In addition, deep-bedded cubicles yielded advantages in this regard. Both regression models for teat and teat tip cleanliness contained similar but not identical predictive variables. This indicates that dirtiness of each particular area may originate from slightly different though related causes. The low correlations found between udder, teat and teat tip cleanliness should be considered in future studies.

A crossbreeding trial was conducted in the hot wet tropical zone of Ceylon at Karagoda-Uyangoda. Sinhala cows were mated to Jersey, Friesian and Sinhala bulls. A few reciprocal matings were done with the Jersey breed.

The milk yields of the Friesian crosses were higher than those of the corresponding Jersey crosses which were higher than those of the Sinhala. The ½ Sinhala ½ Friesian also had a longer lactation and larger body size than the Jersey cross or purebred Sinhala. A decline of about one-third of the milk yield of the F1 was evident in the F2 generation.

The liability to perinatal mortality increased from the F1 generation calves to F3 calves.

A study has been carried out to determine the length of the breeding season and the feasibility of lambing twice a year in Merino sheep in Britain.

Six groups of 18 ewes were exposed to rams at monthly intervals, and twice per year, from April 1969 to June 1970. A well-defined breeding season, from August to January, was found, and its shortness, linked with the inability of the ewes to conceive immediately post partum, prevented lambing twice in the year.