At calving, purebred animals of the Belgian Blue (BB) breed are compromised by the incompatibility in size and shape of the dam and her calf, resulting in a very high incidence of dystocia problems. To clarify which body parts of the calf are of decisive importance to allow natural delivery and to investigate both the mean value as well as the variation among these body sizes within this breed (variation being an important condition for selection), measurements of nine body parts (body weight at birth (BW), body length (BL), length of the head (LH), shoulder width (SW), hip width (HW), heart girth (HG), withers height (WH) and the circumference of the fetlock of both the front (CFF) and the hind leg (CFH)) were assessed in 147 newborn purebred BB calves on 17 farms. Simple and partial correlations were assessed and we examined whether environmental factors (gender of the calf, parity of the cow, type of calving, season of birth and time of measurement after birth) were significantly associated with these specific calf measurements. The mean BW was 49.2 ± 7.1 kg. The average BL was 56.4 ± 4.5 cm and the mean LH was 24.4 ± 2.3 cm. Measurements obtained for SW and HW were 22.4 ± 2.2 and 22.9 ± 2.1 cm, respectively, whereas the mean WH was 71.1 ± 4.7 cm. Measurements of circumferences revealed a CFF of 17.9 ± 1.1 cm, a CFH of 18.0 ± 1.0 cm and a mean HG of 78.0 ± 5.4 cm. Partial correlations of the BW with eight body measurements were significant (P < 0.01) and ranged between 0.17 and 0.85; 0.42 and 0.88; and 0.24 and 0.88 when corrected for gender, parity and type of calving, respectively. BL (P < 0.01) and the CFF and CFH (P < 0.001) are larger in bull calves than in heifer calves. Calves born through caesarean section had broader SW (P < 0.01) and HW (P < 0.01) when compared with calves born after natural calving (defined as born per vaginam without assistance or with slight traction). Sizes of calves born out of multiparous cows were generally larger than of calves born out of heifers (SW: P < 0.001; HW: P < 0.05). As SW and HW are the broadest points of a BB calf, they are both candidates for being the limiting measures for calving ease, but the difference between HW and SW for the total data set was not different from zero (P > 0.05). In contrast to male calves in which no significant difference (between HW and SW) could be found, female calves show the difference between HW and SW that was significantly different from zero (P < 0.001); thus, in female calves, the HW is the most limiting factor of the calf’s body. The significant variation in some body measures between the calves and the strong correlation within these sizes raises the possibility of selection towards smaller calves aiming to limit the dystocia problem in the BB breed. Furthermore, on the basis of our results, we were able to build equations for the farmer to use at the moment of calving containing the LH, the CF and the calf’s gender to estimate SW and HW, the limiting body parts of the calf to be born naturally. Together with the knowledge of the pelvic size of the dam, this information gives the obstetrician or the farmer a more accurate prediction of the probability of natural calving at parturition.

Empirical and factorial methods are currently used to estimate nutrient requirements for domestic animals. The purpose of this study was to estimate the nutrient requirements of a given pig population using the empirical and factorial methods; to establish the relationship between the requirements estimated with these two methods; and to study the limitations of the methods when used to determine the level of a nutrient needed to optimize individual and population responses of growing pigs. A systematic analysis was carried out on optimal lysine-to-net-energy (Lys : NE) ratios estimated by the empirical and factorial methods using a modified InraPorc® growth model. Sixty-eight pigs were individually simulated based on detailed experimental data. In the empirical method, population responses were estimated by feeding pigs with 11 diets of different Lys : NE ratios. Average daily gain and feed conversion ratio were the chosen performance criteria. These variables were combined with economic information to estimate the economic responses. In the factorial method, the Lys : NE ratio for each animal was estimated by model inversion. Optimal Lys : NE ratios estimated for growing pigs (25 to 105 kg) differed between the empirical and the factorial method. When the average pig is taken to represent a population, the factorial method does not permit estimation of the Lys : NE ratio that maximizes the response of heterogeneous populations in a given time or weight interval. Although optimal population responses are obtained by the empirical method, the estimated requirements are fixed and cannot be used for other growth periods or populations. This study demonstrates that the two methods commonly used to estimate nutrient requirements provide different nutrient recommendations and have important limitations that should be considered when the goal is to optimize the response of individuals or pig populations.

An experiment was conducted to evaluate the effects of cereal carbohydrate form (isolated v. cereal matrix) and level, especially mixed-linked β-glucan (hereafter referred to as β-glucan) and starch amylase/amylopectin ratio on nutrient digestibility and fermentation parameters in the intestines of weaned pigs. Four hulless barley cultivars containing varying β-glucan levels (41 to 84 g/kg) were compared with hulled barley, supplemented or not with a β-glucan concentrate (BBG; 270 g/kg β-glucan) and two oat cultivars for digestibility and fermentation metabolites. Seventy-two weaned piglets (BW = 12.8 ± 1.9 kg) were assigned to one of nine diets composed of 815 g/kg cereal, 60 g/kg whey, 90 g/kg soy protein isolate and 35 g/kg minerals. After 15 days, the pigs were killed, and digesta collected from ileum and colon were analyzed for proximate nutrients, short-chain fatty acids (SCFAs), lactic acid (LA) and ammonia. Ileal and total tract digestibility of proximate nutrients and non-starch polysaccharides (NSPs) were determined using HCl-insoluble ash as a marker. Organic matter (OM) ileal digestibility was greater (P < 0.05) for diets based on hulless barley (77% ± 1.1% on average), as compared with hulled barley (64% ± 1.4%) and oat (58% ± 1.5%). Similar trends were found for total tract OM digestibility, varying from 90% ± 0.3% for hulless barley to 67% ± 0.4% for oat, on average. NSP digestibility differed (P < 0.05) within and between cereal types, ranging from 20% (hulled barley plus 163 g/kg BBG or ∼40 g/kg β-glucan) to 51% (SB94893 hulless barley cultivar with high β-glucan and high amylose ratio) at the ileum and from 44% (hulled barley) to 84% (SB94893 cultivar) at the total tract level. No dietary effect (P > 0.05) was found for SCFA concentration in ileal contents, whereas in colonic contents, SCFA was lower in pigs fed oat (P < 0.001). LA concentration was greater (P < 0.001) in the colon of pigs fed hulless barley than in pigs fed hulled barley and oat. Expressed per kg carbohydrate (NSP + starch) fermented, the ammonia concentration at the colon was lowest for hulled barley diets (supplemented with β-glucan) and the highest for oat diets. In conclusion, the interaction of both form and level of β-glucan impacted nutrient digestibility and fermentation. Hulless barleys with high soluble NSP such as β-glucan and resistant starch yielded, in general higher SCFA and LA and lower ammonia. Hulless barleys may, therefore, have potential for use in feeding strategies designed to improve gut health in pigs.

To obtain quantitative information that can be later used in animal welfare modelling, the relationship between the lying behaviour of growing-finishing pigs (initial body weight (BW) between 19 and 87 kg) and different factors related to the housing conditions, with a potential negative effect on their welfare, was studied by means of a meta-analytical approach. Data from 22 experiments reported in 21 scientific publications were collected. The space allowance, expressed on an allometric basis by means of a k-value (m2/BW0.667), the group size (n) and the floor characteristics (fully and partly slatted v. non-slatted floor), as well as their significant two-way interactions were used as fixed effects, and the experiment was used as a random factor to take into account the interexperiment effect. Further regression analyses were performed on the predicted values of observations in order to improve the adjustment of data. A significant quadratic relationship was established between space allowance (k-value, P < 0.05; squared k-value, P < 0.01) and the percentage of time spent lying. A significant interaction between the k-value and the floor type was also found (P < 0.05), showing that the relationship between space allowance and lying behaviour is affected by the presence or absence of slats. Threshold k-values were obtained using broken-line analyses, being about 0.039 for slatted floors and almost double for non-slatted floors. Compared to other studies, these values suggest that the ability to rest as space availability decreases may be compromised before a reduced performance becomes apparent. Group size did not show a significant effect. Additional information should be added to the model, as further data become available, to adjust the proposed parameters as well as to try to include the effect of other important aspects such as that of ambient temperature.

Elevated dietary nitrate (NO3−) is associated with production losses in ruminant livestock, resulting in substantial economic losses incurred by producers. Severe drought, fertilization practices and poorly maintained pastures increase the risk of elevated NO3− intake among cattle and sheep. Nitrate is metabolized to nitrite (NO2−) in the rumen and further reduced to ammonia. Ruminants consuming high dietary NO3− vary in ability to efficiently reduce excess NO2− to ammonia. This leads to methemoglobin formation and ultimately NO3− toxicity signs. Variation in individual tolerance to elevated dietary NO3− can be partially attributed to rate and duration of exposure, rate of elimination, metabolism, species and dose. Our objectives were to confirm and quantify variation in individual tolerance to subacute levels of dietary NO3−, and determine if individuals could be identified as highly or lowly tolerant to elevated dietary NO3− based on production traits, plasma analytes and(or) signs of subacute NO3− toxicity. Purebred Suffolk ewes were administered supplement mixed with tap water (control; n = 8) or potassium nitrate (NO3− treated; 300 mg NO3−/kg BW daily; n = 47) for 8 days. Coefficients of variation (CV) indicated that supplement intake was more variable in NO3− treated ewes (CV = 59.3%) than in control ewes (CV = 13.6%). Among NO3− treated ewes, six ewes highly tolerant and six ewes lowly tolerant to elevated dietary NO3− were identified based on individual performance, NO3− treated supplement intake, and signs of toxicity. Supplement intake was lower (P < 0.0001) in NO3− treated ewes than in control ewes, indicating elevated dietary NO3− influences feed intake. Supplement intake differed (P < 0.0001) between control, highly tolerant and lowly tolerant ewes. Supplement intake of highly and lowly tolerant ewes was 82% and 23%, respectively, of the control ewes’ intake. Weight change and plasma concentrations of NO2−, cortisol, glucose and retinol were not different (P ⩾ 0.38) among control, highly tolerant and lowly tolerant ewes. Plasma urea nitrogen (PUN) levels were not different (P = 0.25) between control and lowly tolerant ewes, but were lower (P = 0.02) in highly tolerant ewes than in control ewes. Furthermore, PUN and NO3− treated supplement intake were highly correlated (0.71; P < 0.0001) in lowly tolerant ewes. These results confirm and quantify variation in response to subacute levels of dietary NO3− and indicate that individuals can be identified as highly or lowly tolerant to elevated dietary NO3− based on their performance and NO3− toxicity signs.

Several physiological and biological variables are known to affect peroxisome proliferator-activated receptor (PPAR)-α-dependent signaling pathway and plasma biochemical profiles. However, less is known about the effect of these variables on high-fat diet-fed mice. In a 5-week study, C57BL/6 mice were divided into control (C) and high-fat diet-fed (H) groups, whereby before dissection, each group was subdivided into non-fasted (nC and nH) and a 15-h fasted mice (fC and fH) killed in the early light cycle, and a 15-h fasted mice (eC and eH) killed in the late phase of the light cycle. Liver and blood from the vena cava were collected. Non-fasted nC and nH mice have a marginal difference in their body weight gain, whereas significant differences were found for fasted mice. In nH mice, PPAR-α, acyl-CoA oxidase and insulin-like growth factor-binding protein expressions were significantly elevated, in contrast to fatty acid synthase (Fasn), stearoyl CoA-desaturase (SCD)-1, and elongase (ELOVL)-6 expressions. Fasn was profoundly induced in fH mice, while decreased sterol regulatory-binding protein-1 and SCD-1 were found only in eH mice. Different from the gene expression profiles, plasma total cholesterol level of the eH mice was higher than controls, whereas nH mice have increased plasma non-esterified fatty acids. Only glucose level of the fH mice was higher than that observed for controls. Results showed that fasting and sampling time have significantly affected liver gene expression and plasma biochemical indices of the high-fat diet-treated mice. An overlook in these aspects can cause serious discrepancies in the experimental data and their interpretations.

A better understanding of the factors regulating feed efficiency and their potential as predictors of feed efficiency in cattle is needed. Therefore, the potential of three classes of traits, namely, feeding behavior characteristics: daily time at feeder (TF; min/day), time per meal (TM; min), meal size (MS; g DM), eating rate (ER; g DM/min), number of daily meals (NM) and daily visits to the feeder (VF); infrared (IR) thermography traits (°C): eye (EY), cheek (CK), snout (SN), ribs (RB) and hind area (HA); and glucocorticoid levels: fecal cortisol metabolites (FCM; ng/g) and plasma cortisol (PC; ng/ml) as predictors of efficiency were evaluated in 91 steers (436 ± 37 kg) over 2 years (Y1 = 46; Y2 = 45). Additionally, the individual traits of each of these three classes were combined to define three single traits. Individual daily feed intake of a corn silage and high-moisture corn-based diet was measured using an automated feeding system. Body weight and thermographs were taken every 28 days over a period of 140 days. Four productive performance traits were calculated: daily dry matter intake (DMI), average daily gain (ADG), feed to gain ratio (F : G) and residual feed intake (RFI). Steers were also classified into three RFI categories (low-, medium- and high-RFI). Among the feeding behavior characteristics, MS and ER were correlated with all efficiency traits (range: 0.26 to 0.75). Low-RFI (more efficient steers) had smaller MS, lower ER and fewer VF in comparison to high-RFI steers. Less efficient steers (high-RFI) performed more VF during the nocturnal period than more efficient steers. More efficient steers had lower CK and SN temperatures than less efficient steers (28.1°C v. 29.2°C and 30.0°C v. 31.2°C), indicating greater energetic efficiency for low-RFI steers. In terms of glucocorticoids, PC was not correlated with efficiency traits. In contrast, more efficient steers had higher FCM in comparison to less efficient steers (51.1 v. 31.2 ng/g), indicating that a higher cortisol baseline is related to better feed efficiency. The overall evaluation of the three classes of traits revealed that feeding behavior, IR thermography and glucocorticoids accounted for 18%, 59% and 7% of the total variation associated with RFI, respectively. These classes of traits have usefulness in the indirect assessment of feed efficiency in cattle. Among them, IR thermography was the most promising alternative to screen cattle for this feed efficiency. These findings might have application in selection programs and in the better understanding of the biological basis associated with productive performance.

The short-tailed sheep, native of an area stretching from Russia to Iceland, are generally considered a primitive type. These robust northern sheep seem to have been spread by Norse vikings to several countries in this area from the late eighth century to the middle of the eleventh century ad. They have several common characteristics in addition to the fluke-shaped and tapered short tail, such as a wide range of colour patterns, dual-coated wool and the ability to thrive under harsh environmental conditions, often in isolated marginal areas. While 34 short-tailed breeds of North European origin can still be identified, it is clear that their population sizes have declined in most cases and several of them are now rare and endangered. Although these breeds have mainly been confined to certain localities, some of them have gained considerable distribution due to their genetic merits, such as prolificacy. Of these, the Finnsheep and the Romanov are best known being exported to several countries in the world where their genetic material has been utilized through crossbreeding with local sheep. This has resulted in the production of some new synthetic breeds. Meat is now generally the main product of the North European short-tailed breeds and their crossbreds, whereas wool, skins and milk are normally regarded as byproducts, yet of considerable economic importance in some cases. Such breeds have clearly a role to play in sustainable grassland-based production systems in the future.

Epistasis is an important feature of the genetic architecture of quantitative traits. Previously, we showed that startle-induced locomotor behaviour of Drosophila melanogaster, a critical survival trait, is highly polygenic and exhibits epistasis. Here, we characterize epistatic interactions among homozygous P-element mutations affecting startle-induced locomotion in the Canton-S isogenic background and in 21 wild-derived inbred genetic backgrounds. We find pervasive epistasis for pairwise combinations of homozygous P-element insertional mutations as well as for mutations in wild-derived backgrounds. In all cases, the direction of the epistatic effects is to suppress the mutant phenotypes. The magnitude of the epistatic interactions in wild-derived backgrounds is highly correlated with the magnitude of the main effects of mutations, leading to phenotypic robustness of the startle response in the face of deleterious mutations. There is variation in the magnitude of epistasis among the wild-derived genetic backgrounds, indicating evolutionary potential for enhancing or suppressing effects of single mutations. These results provide a partial glimpse of the complex genetic network underlying the genetic architecture of startle behaviour and provide empirical support for the hypothesis that suppressing epistasis is the mechanism underlying genetic canalization of traits under strong stabilizing selection. Widespread suppressing epistasis will lead to underestimates of the main effects of quantitative trait loci (QTLs) in mapping experiments when not explicitly accounted for. In addition, suppressing epistasis could lead to underestimates of mutational variation for quantitative traits and overestimates of the strength of stabilizing selection, which has implications for maintenance of variation of complex traits by mutation–selection balance.

Several studies have shown that feeding of an energy-dense diet over short periods to cull cows could be profitable in terms of increased saleable yield and improved carcass conditions. Although the application of growth promoters, such as anabolic implants and beta agonists, in finishing of cull cows have been recorded, there is no conclusive evidence as to the timing and duration of beta agonists in cull cow production. In this study, 288 cull cows with four or more permanent incisors and varying weights and body conditions were divided into four treatment groups so that variation in age, weight and body condition were equally distributed among groups. One group received concentrate feed without any beta agonist (C), whereas the other three groups also received concentrate feed with zilpaterol hydrochloride (6 p.p.m.) for 20 (Z20), 30 (Z30) or 40 (Z40) days, respectively, followed by a 2-day withdrawal. Animals were adapted for 10 days on a grain-based diet and fed an additional 40 days before slaughter. Growth rate and efficiency (live and carcass), trimmed meat yield and meat tenderness (Warner Bratzler shear force and sensory) of the aged (10 days) m. longissimus thoracis (LT) and m. semitendinosus (ST) were recorded. In general, Z cows had higher carcass gains and efficiency of gain than C cows (P < 0.05). In addition, Z carcasses showed higher proportional trimmed meat yields than C carcasses (P < 0.05). No significant differences in tenderness measurements were recorded for LT or ST. In general, supplementation of zilpaterol for 30 days showed better growth performance and higher trimmed meat yield than 20 and 40 days supplementation.

A number of farmed species are characterized by breeding populations of large full-sib families, including aquaculture species and outcrossing plant species. Whole genome association studies in such species must account for stratification arising from the full-sib family structure to avoid high rates of false discovery. Here, we demonstrate the value of selective genotyping strategies which balance the contribution of families across high and low phenotypes to greatly reduce rates of false discovery with a minimal effect on power.

The demand for special breeding programmes for organic pig meat production is based on the assumption that pigs kept under organic conditions need different biological properties compared with conventionally kept pigs in order to achieve a good performance. This would mean that genotype–environment interactions exist. Therefore, 682 pigs of seven different genotypes were tested for growth performance and carcass quality under conventional and organic environments at two testing stations to verify genotype–environment interactions. All genotypes achieved significantly better results within the conventional environment and there were significant interactions between genotype and environment for all the criteria of growth performance and carcass quality. The interactions are mainly caused by varying differences between organic and conventional systems within genotypes, but for all traits, except weight gain, no major shift of the ranking order within environment between genotypes. Although statistically significant genotype–environment interactions exist, the modern genotypes selected under conventional conditions are also superior to indigenous breeds under organic conditions in economically important traits. Hence, it can be concluded from these results that no special breeding programme is necessary for organic production systems.

Piglets, separated from their dam at 12 days of age and fed a milk substitute hourly, were used as a model for suckling. Animals were fitted with a terminal ileal T-cannula and a jugular vein catheter. At 28 days of age, half of the pigs had a dietary change to a cereal-based weaner diet fed as slurry, and the others remained on milk substitute. Animals were labelled by oral administration of 15N-labelled yeast for 10 days (days 15 to 25). Blood samples were taken twice a day to monitor 15N enrichment of the blood plasma. Diets included polyethylenglycol (PEG 4000) to allow calculation of apparent ileal digestibility of nitrogen and individual amino acids. Ileal bacterial nitrogen was calculated from D-alanine content of the digesta. Furthermore, small intestinal (SI) villus height and crypt depth were measured. Feed intake was increased by the dietary change. The total nitrogen flow was 3.2 ± 0.4 g/day and 5.9 ± 0.4 for the milk and weaner diet, respectively. Endogenous nitrogen flow at the terminal ileum was similar for both groups (milk diet 2.4 ± 0.4 v. weaner diet 2.2 ± 0.3 g/day), whereas the bacterial nitrogen content (0.08 ± 0.01 g/day milk diet v. 0.15 ± 0.01 g/day weaner diet, P < 0.01) and exogenous nitrogen flow (0.94 ± 0.16 g/day milk diet v. 3.29 ± 0.12 g/day weaner diet, P < 0.001) increased significantly in the weaner-diet group. The ileal apparent digestibility coefficient of protein was 0.81 ± 0.06 and 0.68 ± 0.01 for the milk replacer and the weaner diet, respectively. Morphology measurements made along the SI at 25%, 50% and 75% were similar between piglets fed milk replacer and those fed a cereal-based weaner diet. The only statistical effect (P < 0.01) of dietary change was an increase in crypt depth in the weaner-diet group. In conclusion, pigs, following a dietary change analogous to weaning, lack the capacity to fully digest a standard weaner diet. This may result in an increased nutrient content entering the large intestine and an altered microbiota. In the absence of a period of anorexia, often associated with traditional weaning, we saw no evidence of villous atrophy, but report here a significant crypt hyperplasia, especially at the 75% level, as a result of dietary change.