This study was conducted to investigate whether methionyl-tRNA synthetase (MetRS) is a mediator of methionine (Met)-induced crop milk protein synthesis via the janus kinase 2 (JAK2)/signal transducer and activator of transcription 5 (STAT5) signalling pathway in breeding pigeons. In Experiment 1, a total of 216 pairs of breeding pigeons were divided into three groups (control, Met-deficient, and Met-rescue groups). In Experiments 2 and 3, forty pairs of breeding pigeons from each experiment were allocated into four groups. The second experiment included a control group and three MetRS inhibitor (REP8839) groups. The third experiment included a Met-deficient group, Met-sufficient group, REP8839 + Met-deficient group and REP8839 + Met-sufficient group. Experiment 1 showed that Met supplementation increased crop development, crop milk protein synthesis, the protein expression of MetRS and JAK2/STAT5 signalling pathway, and improved squab growth. Experiment 2 showed that crop development, crop milk protein synthesis and the protein expression of MetRS and the JAK2/STAT5 signalling pathway were decreased, and squab growth was inhibited by the injection of 1·0 mg/kg body weight REP8839, which was the selected dose for the third experiment. Experiment 3 showed that Met supplementation increased crop development, crop milk protein synthesis and the expression of MetRS and JAK2/STAT5 signalling pathway and rescued squab growth after the injection of REP8839. Moreover, the co-immunoprecipitation results showed that there was an interaction between MetRS and JAK2. Taken together, these findings indicate that MetRS mediates Met-induced crop milk protein synthesis via the JAK2/STAT5 signalling pathway, resulting in improved squab growth in breeding pigeons.

Camelina cake (CAM) is a co-product proposed as an alternative protein source; however, piglet data are still limited. This study aimed to evaluate the effect of different doses of CAM in substitution of soyabean meal on the growth, health and gut health of weaned pigs. At 14 d post-weaning (d0), sixty-four piglets were assigned either to a standard diet or to a diet with 4 %, 8 % or 12 % of CAM. Piglets were weighed weekly. At d7 and d28, faeces were collected for microbiota and polyamine and blood for reactive oxygen metabolites (ROM) and thyroxine analysis. At d28, pigs were slaughtered, organs were weighed, pH was recorded on gut, colon was analysed for volatile fatty acids (VFA) and jejunum was used for morphological and gene expression analysis. Data analysis was carried out using a mixed model including diet, pen and litter as factors; linear and quadratic contrasts were tested. CAM linearly reduced the average daily gain from d0–d7, d0–d14, d0–d21 and d0–d28 (P ≤ 0·01). From d0–d7 increasing CAM linearly decreased feed intake (P = 0·04) and increased linearly the feed to gain (P = 0·004). CAM increased linearly the liver weight (P < 0·0001) and affected the cadaverine (P < 0·001). The diet did not affect the ROM, thyroxine, intestinal pH, VFA and morphology. All doses of CAM increased the α diversity indices at d28 (P < 0·05). CAM at 4 % promoted the abundance of Butyricicoccaceae_UCG-008. Feeding with CAM enhanced resilience in the gut microbiome and can be evaluated as a potential alternative protein source with dose-dependent limitations on piglet growth performance.

This study aimed at the performance evaluation of a closed flock of Marwari sheep and also to study the effect of accumulated inbreeding on the growth traits using a linear mixed model methodology. The data generated for 39 years (1981 to 2020) on Marwari sheep maintained at ICAR-Central Sheep & Wool Research Institute, Arid Region Campus (CSWRI, ARC), Bikaner, Rajasthan, India were used for analysis on growth traits. The overall least-squares means (LSM) of live weights at birth (BWT), weaning (3MWT), 6 months (6MWT), 9 months (9MWT) and 12 months (12MWT) were observed to be 3.02 ± 0.01, 14.30 ± 0.04, 20.12 ± 0.05, 23.68 ± 0.06 and 26.39 ± 0.07 kg, respectively. Overall LSM for average daily gain from birth to 3 months (ADG1), 3 to 6 months (ADG2) and 6 to 12 months (ADG3) were 125.44 ± 0.40, 67.37 ± 0.40 and 35.83 ± 0.29 g/day, respectively. Kleiber ratio (KR) from birth to 3 months (KR1), 3 to 6 months (KR2), and 6 to 12 months (KR3) were 16.78 ± 0.02, 6.58 ± 0.04 and 3.05 ± 0.02, respectively. Results revealed a 4.36, 25.83, 36.33, 31.50 and 28.99% improvement in the live weights since the inception of the improvement programme. This is also reflected by a significant effect of sire on all the growth traits. The estimate of inbreeding in the flock was 1.55%. Highly inbred animals were 5.13% (>5% Fi). The study revealed the non-significant effect of inbreeding level on all growth traits except for BWT and KR3. For BWT, inbreeding classes had variation; however, a negative effect was not seen. The inbreeding class (>5% Fi) was reduced by 0.05 units for KR3 as against its preceding class. Dam’s age at lambing and weight influenced the birth weight and subsequent weights. The study concluded that the selection programme of Marwari sheep is in the right direction; however, regular monitoring of inbreeding is necessary and factors affecting growth must be monitored to attain better growth rates in the nucleus.

This study examined the influences of coated folic acid (CFA) and coated riboflavin (CRF) on bull performance, nutrients digestion and ruminal fermentation. Forty-eight Angus bulls based on a randomised block and 2 × 2 factorial design were assigned to four treatments. The CFA of 0 or 6 mg of folic acid/kg DM was supplemented in diets with CRF 0 or 60 mg riboflavin (RF)/kg DM. Supplementation of CRF in diets with CFA had greater increase in daily weight gain and feed efficiency than in diets without CFA. Supplementation with CFA or CRF enhanced digestibility of DM, organic matter, crude protein, neutral-detergent fibre and non-fibre carbohydrate. Ruminal pH and ammonia N content decreased and total volatile fatty acids concentration and acetate to propionate ratio elevated for CFA or CRF addition. Supplement of CFA or CRF increased the activities of fibrolytic enzymes and the numbers of total bacteria, protozoa, fungi, dominant fibrolytic bacteria and Prevotella ruminicola. The activities of α-amylase, protease and pectinase and the numbers of Butyrivibrio fibrisolvens and Ruminobacter amylophilus were increased by CFA but were unaffected by CRF. Blood concentration of folate elevated and homocysteine decreased for CFA addition. The CRF supplementation elevated blood concentrations of folate and RF. These findings suggested that CFA or CRF inclusion had facilitating effects on performance and ruminal fermentation, and combined addition of CFA and CRF had greater increase in performance than CFA or CRF addition alone in bulls.

Phosphorus requirements of reproducing sows were estimated using 24-h urinary P excretion. Thirty-six multiparous sows were fed one of six maize–soybean meal-based diets with total P ranging from 0·40 to 0·80 % in 0·08 % increments with a constant Ca:total P ratio (1·25:1). Diets were fed from day 7·5 ± 1 after breeding until the end of lactation (day 26 ± 1). Urine samples were collected in mid and late gestation (days 77·1 ± 2 and 112·4 ± 1) and early and late lactation (days 4·5 ± 1 and 18·2 ± 1). Phosphorus requirements were estimated using linear and nonlinear regression models. Based on a single 24-h urinary P excretion, estimated daily dietary total P requirements in mid and late gestation were 10·3 g (6·0 g standardised total tract digestible P, STTD P), and estimates for early and late lactation were 31·1 g (16·6 g STTD P) and 40·3 g (22·1 g STTD P), respectively. Plasma P and Ca concentrations were maintained within normal ranges at the estimated levels of P requirements. No differences among treatments were observed for plasma parathyroid hormone (P ≥ 0·06) and bone formation marker (P ≥ 0·16). In lactation, bone resorption marker decreased (P ≤ 0·001) as sows consumed more P. Among the analysed variables, urinary P was the most sensitive response to changes in dietary P intake. Urinary P excretion offers a practical method to estimate P requirements in sows. Our recommended daily total P requirements are 10·3 g for gestation and 35·7 g for lactation.

To investigate the influences of cobalt (Co) and folic acid (FA) on growth performance and rumen fermentation, Holstein male calves (n 40) were randomly assigned to four groups according to their body weights. Cobalt sulphate at 0 or 0·11 mg Co/kg DM and FA at 0 or 7·2 mg/kg DM were used in a 2 × 2 factorial design. Average daily gain was elevated with FA or Co supplementation, but the elevation was greater for supplementing Co in diets without FA than with FA. Supplementing FA or Co increased DM intake and total-tract nutrient digestibility. Rumen pH was unaltered with FA but reduced with Co supplementation. Concentration of rumen total volatile fatty acids was elevated with FA or Co inclusion. Acetate percentage and acetate to propionate ratio were elevated with FA inclusion. Supplementing Co decreased acetate percentage and increased propionate percentage. Activities of xylanase and α-amylase and populations of total bacteria, fungi, protozoa, Ruminococcus albus, Fibrobacter succinogenes and Prevotella ruminicola increased with FA or Co inclusion. Activities of carboxymethyl-cellulase and pectinase increased with FA inclusion and population of methanogens decreased with Co addition. Blood folates increased and homocysteine decreased with FA inclusion. Blood glucose and vitamin B12 increased with Co addition. The data suggested that supplementing 0·11 mg Co/kg DM in diets containing 0·09 mg Co/kg DM increased growth performance and nutrient digestibility but had no improvement on the effects of FA addition in calves.

The objective of this study was to evaluate the effect of feeding Bacillus altitudinis spores to sows and/or offspring on growth and health indicators. On day (D) 100 of gestation, twenty-four sows were selected and grouped as: control (CON), fed with a standard diet; and probiotic (PRO), fed the standard diet supplemented with B. altitudinis WIT588 spores from D100 of gestation until weaning. Offspring (n 144) from each of the two sow treatments were assigned to either a CON (no probiotic) or PRO (B. altitudinis-supplemented) treatment for 28 d post-weaning (pw), resulting in four treatment groups: (1) CON/CON, non-probiotic-supplemented sow/non-probiotic-supplemented piglet; (2) CON/PRO, non-probiotic-supplemented sow/probiotic-supplemented piglet; (3) PRO/CON, probiotic-supplemented sow/non-probiotic-supplemented piglet and (4) PRO/PRO, probiotic-supplemented sow/probiotic-supplemented piglet. B. altitudinis WIT588 was detected in the faeces of probiotic-supplemented sows and their piglets, and in the faeces and intestine of probiotic-supplemented piglets. Colostrum from PRO sows had higher total solids (P = 0·02), protein (P = 0·04) and true protein (P = 0·05), and lower lactose (P < 0·01) than colostrum from CON sows. Maternal treatment improved offspring feed conversion ratio at D0–14 pw (P < 0·001) and increased offspring body weight at D105 and D127 pw (P = 0·01), carcass weight (P = 0·05) and kill-out percentage (P < 0·01). It also increased small intestinal absorptive capacity and impacted the haematological profile of sows and progeny. There was little impact of pw treatment on any of the parameters measured. Overall, the lifetime growth benefits in the offspring of B. altitudinis-supplemented sows offer considerable economic advantages for pig producers in search of alternatives to in-feed antibiotics/zinc oxide.

Fibre content and its effect on chyme viscosity are associated with changes in the digestive system of humans and pigs. It is unclear if fibre content and viscosity affect digestive function independently or interactively. We evaluated apparent ileal digestibility (AID) of nutrients and intestinal function in thirty-six ileal-cannulated barrows fed for 29 d either maize–soyabean meal (MSBM) or high-fibre MSBM + 30 % distillers dried grains with solubles (MSBM + DDGS) modified to three levels of viscosity by adding 5 % non-viscous cellulose (CEL), 6·5 % medium-viscous carboxymethylcellulose (MCMC) or 6·5 % high-viscous CMC (HCMC). Digesta were collected on days 27 and 28 and intestinal samples on day 29. Feeding CMC, regardless of fibre content, increased viscosity of whole digesta (P = 0·003) and digesta supernatant (P < 0·0001) compared with CEL. Feeding MSBM + DDGS or CMC decreased AID of DM (P = 0·003; P < 0·0001) and crude protein (P = 0·02; P < 0·0001) compared with MSBM or CEL. Feeding CMC regardless of fibre content increased jejunal crypt depth (P = 0·02) and ileal goblet cell area (P = 0·004) compared with CEL. Adding DDGS or CMC did not affect villus height and gene expression of jejunal monosaccharide and amino acid transporters. Feeding HCMC, regardless of fibre content, elevated amylase activity by 46 and 50 % in jejunal (P = 0·03) and ileal digesta (P = 0·01) compared with CEL. In summary, diets with increased viscosity decreased nutrient digestibility and induced intestinal changes that were independent of the amount of fibre fed.

The present study was conducted to test the hypothesis that dietary supplementation with a nano chitosan–zinc complex (CP–Zn, 100 mg/kg Zn) could alleviate weaning stress in piglets challenged with enterotoxigenic Escherichia coli K88 by improving growth performance and intestinal antioxidant capacity. The in vivo effects of CP–Zn on growth performance variables (including gastrointestinal digestion and absorption functions and the levels of key proteins related to muscle growth) and the antioxidant capacity of the small intestine (SI) were evaluated in seventy-two weaned piglets. The porcine jejunal epithelial cell line IPEC-J2 was used to further investigate the antioxidant mechanism of CP–Zn in vitro. The results showed that CP–Zn supplementation increased the jejunal villus height and decreased the diarrhoea rate in weaned piglets. CP–Zn supplementation also improved growth performance (average daily gain and average daily feed intake), increased the activity of carbohydrate digestion-related enzymes (amylase, maltase, sucrase and lactase) and the mRNA expression levels of nutrient transporters (Na+-dependent glucose transporter 1, glucose transporter type 2, peptide transporter 1 and excitatory amino acid carrier 1) in the jejunum and up-regulated the expression levels of mammalian target of rapamycin (mTOR) pathway-related proteins (insulin receptor substrate 1, phospho-mTOR and phospho-p70S6K) in muscle. In addition, CP–Zn supplementation increased glutathione content, enhanced total superoxide dismutase (T-SOD) and glutathione peroxidase (GSH-px) activity, and reduced malondialdehyde (MDA) content in the jejunum. Furthermore, CP–Zn decreased the content of MDA and reactive oxygen species, enhanced the activity of T-SOD and GSH-px and up-regulated the expression levels of nuclear factor erythroid 2-related factor 2 (Nrf2) pathway-related proteins (Nrf2, NAD(P)H:quinone oxidoreductase 1 and haeme oxygenase 1) in lipopolysaccharide-stimulated IPEC-J2 cells. Collectively, these findings indicate that CP–Zn supplementation can improve growth performance and the antioxidant capacity of the SI in piglets, thus alleviating weaning stress.

To evaluate the impacts of guanidinoacetic acid (GAA) and coated folic acid (CFA) on growth performance, nutrient digestion and hepatic gene expression, fifty-two Angus bulls were assigned to four groups in a 2 × 2 factor experimental design. The CFA of 0 or 6 mg/kg dietary DM folic acid was supplemented in diets with GAA of 0 (GAA−) or 0·6 g/kg DM (GAA+), respectively. Average daily gain (ADG), feed efficiency and hepatic creatine concentration increased with GAA or CFA addition, and the increased magnitude of these parameters was greater for addition of CFA in GAA− diets than in GAA+ diets. Blood creatine concentration increased with GAA or CFA addition, and greater increase was observed when CFA was supplemented in GAA+ diets than in GAA− diets. DM intake was unchanged, but rumen total SCFA concentration and digestibilities of DM, crude protein, neutral-detergent fibre and acid-detergent fibre increased with the addition of GAA or CFA. Acetate:propionate ratio was unaffected by GAA, but increased for CFA addition. Increase in blood concentrations of albumin, total protein and insulin-like growth factor-1 (IGF-1) was observed for GAA or CFA addition. Blood folate concentration was decreased by GAA, but increased with CFA addition. Hepatic expressions of IGF-1, phosphoinositide 3-kinase, protein kinase B, mammalian target of rapamycin and ribosomal protein S6 kinase increased with GAA or CFA addition. Results indicated that the combined supplementation of GAA and CFA could not cause ADG increase more when compared with GAA or CFA addition alone.

The present study was conducted to evaluate the impact of dietary fully oxidised β-carotene (OxBC, C40H60O15) supplementation during the perinatal period on immune status and productivity in a sow model. At day 85 of pregnancy, 150 sows were allocated to one of three dietary treatments with fifty sows per treatment. The three experimental diets were supplemented with 0, 4 or 8 mg/kg OxBC in the basal diet. The feeding trial was conducted from gestation day 85 until day 21 of lactation. Dietary OxBC supplementation greatly enhanced colostrum IgM, IgA and IgG levels, and the IgM and IgG content of 14-d milk. Dietary OxBC supplementation decreased the TNF-α and IL-8 levels in colostrum, as well as the TNF-α and IL-18 levels in 14-d milk. There was also a tendency towards an increase in the soluble CD14 level in 14-d milk. Although dietary treatments did not affect average daily feed intake nor backfat thickness loss during lactation, dietary OxBC supplementation tended to enhance litter weight and individual piglet weight at weaning. There was a trend towards increased lactose concentration in 14-d milk with increasing dietary OxBC. It is concluded that dietary supplementation with OxBC during the perinatal period enhances the lactose concentration of sow milk and the immune status of sows, which is reflected by improved cytokine status and immunoglobulin concentrations in colostrum and milk, and thus tending to increase litter weight and individual piglet weight at weaning. The results also provide a scientific nutritional reference for perinatal mothers due to the biological similarity between pigs and humans.

This study aimed to evaluate the effect of in ovo feeding (IOF) of vitamin C at embryonic age 11 (E11) on post-hatch performance, immune status and DNA methylation-related gene expression in broiler chickens. A total of 240 Arbor Acres breeder eggs (63 (sem 0·5) g) were randomly divided into two groups: normal saline and vitamin C (VC) groups. After incubation, newly hatched chicks from each group were randomly divided into six replicates with ten chicks per replicate. Hatchability, average daily feed intake (D21–42 and D1–42), and average daily gain and feed conversion ratio (D1–21) were improved by vitamin C treatment (P < 0·05). IOF of vitamin C increased vitamin C content (D1), total antioxidant capacity (D42), IgA (D1), IgM (D1 and D21), stimulation index for T lymphocyte (D35) and lysozyme activity (D21) in plasma (P < 0·05). On D21, vitamin C increased the splenic expression of IL-4 and DNMT1 and decreased IL-1β, Tet2, Tet3 and Gadd45β expression (P < 0·05). On D42, vitamin C increased the splenic expression of IL-4 and DNMT3A and decreased IFN-γ, Tet3, MBD4 and TDG expression (P < 0·05). In conclusion, the vitamin C via in ovo injection can be absorbed by broiler’s embryo and IOF of vitamin C at E11 improves the post-hatch performance and immune status and, to some extent, the antioxidant capacity of broiler chickens. The expression of enzyme-related DNA methylation and demethylation indicates that the level of DNA methylation may increase in spleen in the VC group and whether the fluctuating expression of pro- and anti-inflammatory cytokines is related to DNA methylation change remained to be further investigated.

Dietary electrolyte balance (dEB) is known to affect acid−base status and mineral metabolism, but is rarely considered in diet formulation for pigs. Yet, the use of a wide variety of local feedstuffs in Europe contributes to lowering the dEB and increasing the fibre content. Hence, mineral requirements may be modified and skeletal health affected. Therefore, the effects of a lower dEB and a higher dietary Ca level on acid−base balance and mineral status were assessed in young pigs fed a diversified diet. A total of twenty-four weaned pigs were fed a control moderate-dEB diet (C) or a diversified moderate-dEB (D), low-dEB (D-A) or low-dEB supplemented with Ca (D-CA) diet. Growth performance, venous blood gas and chemistry, urine pH, mineral balance and femur characteristics were determined. With an equivalent dEB compared with the C diet, the D diet caused an acidification of the urine and increased the excretion of P as a result of a higher dietary content of S. Low-grade metabolic acidosis occurred in piglets fed the D-A diet with changes at systemic and urine levels. A higher excretion of ammonia and P in urine was observed and some bone characteristics tended to be negatively affected. Ca supplementation partially counteracted the effects of low-grade acidosis. Urine excretion of P and ammonia was alleviated and bone characteristics improved. In conclusion, a higher Ca supply must be considered in more diversified diets to counteract the risk of evolving towards low-grade metabolic acidosis which can negatively affect bone.

Determining best practices for managing free farrowing systems is crucial for uptake. Cross-fostering, the exchange of piglets between litters, is routinely performed amongst crate-housed sows. However, cross-fostering can increase fighting amongst the litter and may be more challenging within free farrowing systems as sows have more freedom to respond to cross-fostered piglets. This study compared the effect of either cross-fostering (FOS), or a control of sham-fostering (CON), of four focal piglets per litter on Day 6 postpartum in crates (CRATE) and free farrowing pens (PEN). The post-treatment behavioural responses of sows were recorded (Day 6 = 60 min; Day 7 = 300 min; n = 48), as were the average daily gain (ADG; g/day), total weight gain (TWG; kg) and body lesion scores of focal piglets and their littermates throughout lactation (Day 6, Day 8, Day 11 and Day 26; n = 539) and the post-weaning period (Day 29, Day 32 and Day 60; n = 108). On Day 6, though post-reunion latency to nursing did not differ, latency to successful nursing was longer amongst FOS than CON litters (P < 0.001), more so amongst CRATE FOS than PEN FOS (P < 0.01). On Day 7, PEN FOS sows had fewer successful nursing bouts (P < 0.05) and exhibited decreased lateral (P < 0.01) and increased ventral lying frequencies (P < 0.01) compared to all other housing and treatment combinations. Focal piglet ADG was lower for FOS than CON in the CRATE during Day 6 to Day 8 (P < 0.01) and lower in the PEN during Day 6 to Day 8 (P < 0.001), Day 8 to Day 11 (P < 0.01) and Day 11 to Day 26 (P < 0.05). The TWG of pre-weaned focal piglets (Day 6 to Day 26) was higher amongst CON than FOS litters (P = 0.01). Post-weaning, piglet ADG was higher for PEN than CRATE during Day 26 to Day 29 (P < 0.01) and higher for FOS than CON during Day 26 to Day 29 (P < 0.05), Day 29 to Day 32 (P < 0.001) and Day 32 to Day 60 (P < 0.01); thus, TWG was higher for FOS than CON during the weaner (P = 0.001) and the combined lactation and weaner periods (P = 0.09). In conclusion, sow behaviour was disrupted by cross-fostering in the crates and pens and continued to be disturbed on the following day amongst penned sows. FOS piglets exhibited reduced ADG after cross-fostering, which extended throughout lactation in the pens. However, the increased post-weaning weight gain of FOS piglets meant that their TWG was higher than CON piglets, irrespective of the farrowing system used.

Ruminants fed high-forage diets usually have a low feed efficiency, and their performances might be limited by methionine (Met) supply. However, the INRA feeding system for growing cattle does not give recommendation for this amino acid (AA). This study aimed to assess the effects of Met-balanced diets on animal performance and N metabolism in young bulls fed high-forage diets formulated at or above protein requirements. Four diets resulting from a factorial arrangement of two protein levels (Normal (13·5 % crude protein) v. High (16·2 % crude protein)) crossed with two Met concentrations (unbalanced (2·0 % of metabolisable protein) v. balanced (2·6 % of metabolisable protein)) were tested on thirty-four fattening Charolais bulls for 7 months before slaughter. Animal growth rate was greater in Met-balanced diets (+8 %; P = 0·02) with a trend for a greater impact in High v. Normal protein diets (P = 0·10). This trend was observed in lower plasma concentrations of branched-chain AA only when Met supplementation was applied to the Normal protein diet (P ≤ 0·06) suggesting another co-limiting AA at Normal protein level. Feed conversion efficiency and N use efficiency were unaffected by Met supplementation (P > 0·05). However, some plasma indicators suggested a better use of AA when High protein diets were balanced v. unbalanced in Met. The proportion of total adipose tissue in carcass increased (+5 percent units; P = 0·03), whereas that of muscle decreased on average 0·8 percent units (P = 0·05) in Met-balanced diets. Our results justify the integration of AA into dietary recommendations for growing cattle.

Feeding strategies for growing monogastric livestock (particularly pigs) must focus on maximising animal performance, while attempting to reduce environmental P load. Achieving these goals requires a comprehensive understanding of how different P feeding strategies affect animal responses and an ability to predict P retention. Although along with Ca, P is the most researched macromineral in pig nutrition, knowledge gaps still exist in relation to: (1) the effects of P feed content on feed intake (FI); (2) the impact of P intake on body composition; (3) the distribution of absorbed P to pools within the body. Here, we address these knowledge gaps by gathering empirical evidence on the effects of P-deficient feeds and by developing a predictive, mechanistic model of P utilisation and retention incorporating this evidence. Based on our statistical analyses of published literature data, we found: (1) no change in FI response in pigs given lower P feed contents; (2) the body ash–protein relationship to be dependent upon feed composition, with the isometric relationship only holding for pigs given balanced feeds and (3) the priority to be given towards P retention in soft tissue over P retention in bones. Subsequent results of the mechanistic model of P retention indicated that a potential reduction in P feeding recommendations could be possible without compromising average daily gain; however, such a reduction would impact P deposition in bones. Our study enhances our current knowledge of P utilisation and by extension excretion and could contribute towards developing more accurate P feeding guidelines.

Flax seed meal (FSM) is rich in various nutrients, especially CP and energy, and can be used as animal protein feed. In animal husbandry production, it is a long-term goal to replace soybean meal (SBM) in animal feed with other plant protein feed. However, studies on the effects of replacing SBM with FSM in fattening sheep are limited. The aim of this experiment was to study the effects of replacing a portion of SBM with FSM on nutrient digestibility, rumen microbial protein synthesis and growth performance in sheep. Thirty-six Dorper × Small Thin-Tailed crossbred rams (BW = 40.4 ± 1.73 kg, mean ± SD) were randomly assigned into four groups. The dietary treatments (forage/concentrate, 45 : 55) were isocaloric according to the nutrient requirements of rams. Soybean meal was replaced with FSM at different levels (DM basis): (1) 18% SBM (18SBM), (2) 12% SBM and 6% FSM (6FSM), (3) 6% SBM and 12% FSM (12FSM) and (4) 18% FSM (18FSM). The rams were fed in individual pens for 60 days, with the first 10 days for adaptation to diets, and then the digestibility of nutrients was determined. There was no significant difference in DM intake, but quadratic (P < 0.001) effects on the average daily gain and feed efficiency were detected, with the highest values in the 6FSM and 12FSM groups. For DM and NDF digestibility, quadratic effects were observed with the higher values in the 6FSM and 12FSM groups, but the digestibility of CP linearly decreased with the increase in FSM in the diet (P = 0.043). There was a quadratic (P < 0.001) effect of FSM inclusion rate on the estimated microbial CP yield. However, the values of intestinally absorbable dietary protein decreased linearly (P < 0.001). For the supply of metabolisable protein, both the linear (P = 0.001) and quadratic (P = 0.044) effects were observed with the lowest value in the 18FSM group. Overall, the results indicated that SBM can be effectively replaced by FSM in the diets of fattening sheep and the optimal proportion was 12.0% under the conditions of this experiment.

Genetic selection for increased sow prolificacy has resulted in decreased mean piglet birth weight. This study aimed to investigate the effect of l-carnitine (CAR) supplementation to sows during gestation and/or lactation on sow productivity, semitendinosus muscle (STM) maturity and lifetime growth in progeny. Sixty-four sows were randomly assigned to one of the four dietary treatments at breeding until weaning: CONTROL (0 mg CAR/d), GEST (125 mg CAR/d during gestation), LACT (250 mg CAR/d during lactation) and BOTH (125 mg CAR/d during gestation and 250 mg CAR/d during lactation). The total number of piglets born per litter was greater for sows supplemented with CAR during gestation (17·3 v. 15·8 (sem 0·52); P < 0·05). Piglet birth weight (total and live) was unaffected by sow treatment (P > 0·05). Total myofibre number (P = 0·08) and the expression level of selected myosin heavy chain genes in the STM (P < 0·05) were greater in piglets of sows supplemented with CAR during gestation. Pigs from sows supplemented with CAR during gestation had lighter carcasses at slaughter than pigs from non-supplemented sows during gestation (83·8 v. 86·7 (sem 0·86) kg; P < 0·05). In conclusion, CAR supplementation during gestation increased litter size at birth without compromising piglet birth weight. Results also showed that the STM of piglets born to sows supplemented with CAR during gestation was more developed at birth. However, carcass weight at slaughter was reduced in progeny of sows supplemented with CAR during gestation. The CAR supplementation strategy applied during gestation in this study could be utilised by commercial pork producers to increase sow litter size and improve offspring muscle development.

The present study evaluated the interaction effects of n-3 fatty acids (from linseed oil (LSO), 0 v. 2·5, % DM basis) with rumen undegradable:degradable protein (RUP:RDP) ratios (low ratio (LR) 27:73; high ratio (HR) 38:62 based on crude protein %) in dairy calves’ starter diet. Forty-eight 3-d-old female Holstein dairy calves (41·5 kg of body weight (BW)) were allocated in a 2 × 2 factorial arrangements in the following treatments (n 12 calves/each): (1) no supplementation of LSO with LR (NLSO-LR); (2) no supplementation of LSO with HR (NLSO-HR); (3) supplementation of LSO with LR (LSO-LR) and (4) supplementation of LSO with HR (LSO-HR). The calves were weaned on day 53 of the experiment and remained in the study until day 73. Intake was not affected by LSO and RUP:RDP ratio. However, average daily gain (ADG) was improved with LSO supplementation. Feeding the HR diet increased ADG compared with the LR diet during the entire period. Final BW was greater in calves fed on the LSO than those fed the NLSO diet. Microbial protein production did not differ among treatments. Calves fed on LSO diets had greater feed efficiency than those which were not fed on LSO diets. The calves supplemented with LSO had greater wither and hip heights compared with the unsupplemented calves. The glucose, cholesterol, HDL and insulin concentrations increased in calves supplemented with LSO. In conclusion, the HR diet improved calves’ performance post-weaning; however, LSO could enhance growth performance of dairy calves during the pre-weaning period.

This study evaluated the effects of rumen-protected folic acid (RPFA) and betaine (BT) on growth performance, nutrient digestion and blood metabolites in bulls. Forty-eight Angus bulls were blocked by body weight and randomly assigned to four treatments in a 2 × 2 factorial design. BT of 0 or 0·6 g/kg DM was supplemented to diet without or with the addition of 6 mg/kg DM of folic acid from RPFA, respectively. Average daily gain increased by 25·2 and 6·29 % for addition of BT without RPFA and with RPFA, respectively. Digestibility and ruminal total volatile fatty acids of neutral-detergent fibre and acid-detergent fibre increased, feed conversion ratio and blood folate decreased with the addition of BT without RPFA, but these parameters were unchanged with BT addition in diet with RPFA. Digestibility of DM, organic matter and crude protein as well as acetate:propionate ratio increased with RPFA or BT addition. Ruminal ammonia-N decreased with RPFA addition. Activity of carboxymethyl cellulase, cellobiase, xylanase, pectinase and protease as well as population of total bacteria, protozoa, Fibrobacter succinogenes and Ruminobacter amylophilus increased with RPFA or BT addition. Laccase activity and total fungi, Ruminococcus flavefaciens and Prevotella ruminicola population increased with RPFA addition, whereas Ruminococcus albus population increased with BT addition. Blood glucose, total protein, albumin, growth hormone and insulin-like growth factor-1 increased with RPFA addition. Addition of RPFA or BT decreased blood homocysteine. The results indicated that addition of BT stimulated growth and nutrient digestion in bulls only when RPFA was not supplemented.