Steroidome and metabolome analysis in gilt saliva to identify potential biomarkers of boar effect receptivity.

Optimal management of gilt reproduction requires oestrus synchronization. Hormonal treatments are used for this purpose, but there is a growing demand for non-hormonal alternatives, especially in organic farms. The boar effect is an important alternative opportunity to induce and synchronize oestrus without hormones. Before puberty, gilts exhibit a 'waiting period' during which boar exposure could induce and synchronize the first ovulation. We searched for salivary biomarkers of this period of boar effect receptivity to improve detection of the gilts to stimulate with the perspective of enhancing the efficacy of the boar effect. Saliva samples were collected from 30 Large-White×Landrace crossbred gilts between 140 and 175 days of age. Gilts were exposed twice a day to a boar and subjected to oestrus detection from 150 to 175 days of age. Among the 30 gilts, 10 were detected in oestrus 4 to 7 days after the first introduction of the boar and were considered receptive to the boar effect, 14 were detected in oestrus more than 8 days after first boar contact, and six did not show oestrus and were considered non-receptive. Saliva samples from six receptive and six non-receptive gilts were analyzed for steroidome and for metabolome using gas chromatography coupled to tandem mass spectrometry and 1H nuclear magnetic resonance spectroscopy, respectively. Four saliva samples per gilt were analyzed: 25 days and 11 days before boar introduction, the day of boar introduction, 3 days later for receptive gilts or 7 days later for non-receptive gilts. Twenty-nine steroids and 31 metabolites were detected in gilt saliva. Salivary concentrations of six steroids and three metabolites were significantly different between receptive and non-receptive gilts: progesterone and glycolate 25 days before boar introduction, 3α5ß20α- and 3ß5α20ß-hexahydroprogesterone, dehydroepiandrosterone, androstenediol, succinate, and butyrate 11 days before boar introduction, and 3ß5α-tetrahydroprogesterone on the day of boar introduction. Thus, nine potential salivary biomarkers of boar effect receptivity were identified in our experimental conditions. Further studies with higher numbers of gilts and salivary sampling points are necessary to ascertain their reliability.

Salivary and urinary metabolome analysis for pre-puberty-related biomarkers identification in porcine.

Estrus synchronization is important for optimal management of gilt reproduction in pig farms. Hormonal treatments, such as synthetic progestogens, are used on a routine basis, but there is a growing demand for non-hormonal alternative breeding tools. Before puberty, gilts exhibit a 'waiting period,' related to the ovarian development and gonadotrophin secretions, during which external stimulations, such as boar exposure, could induce and synchronize first ovulation. Practical non-invasive tools for identification of this period in farms are lacking. During this period, urinary oestrone levels are high, but urine sampling is difficult in group-housed females. The aim of this work was to search for specific biomarkers of the 'waiting period' in saliva and urine. In total, nine 144- to 147-day-old Large White gilts were subjected to trans-abdominal ultrasonography three times a week for 5 weeks until puberty detection (week -5 to week -1 before puberty). Urine and saliva samples were collected for oestrone assay to detect the 'waiting period' and for metabolome analysis using 1H-nuclear magnetic resonance spectroscopy to detect potential biomarkers of the 'waiting period.' Gilts were slaughtered 7 days after puberty detection for puberty confirmation. Results were consistent with ultrasonography data for six gilts. Urine and saliva samples from these six gilts were analyzed. Urinary estrone concentration significantly increased 2 weeks before puberty detection. Metabolome analysis of urine samples allowed the identification of 78 spectral bins, among them, 42 low-molecular-weight metabolites were identified. Metabolome analysis of salivary samples allowed the identification of 59 spectral bins, among them, 23 low-molecular-weight metabolites were detected and 17 were identified. No potential biomarker was identified in urinary samples. In saliva, butyrate and 2HOvalerate, 5.79 ppm (putatively uridine), formate, malonate and propionate could be biomarker candidates to ascertain the pre-puberty period in gilt reproduction. These results confirm that non-invasive salivary samples could allow the identification of the physiological status of the gilts and presumably the optimal time for application of the boar effect. This could contribute to synchronize puberty onset and hence to develop non-hormonal breeding tools.

Supplying dextrose before insemination and L-arginine during the last third of pregnancy in sow diets: effects on within-litter variation of piglet birth weight.

Preweaning piglet mortality is largely attributed to the incidence of low birth weight and birth weight variation within the litter. Therefore, developing strategies to increase within-litter uniformity of piglet birth weight is important. This study investigated the effects of different feeding strategies based on specific nutrient supplies in sow diet on the within-litter variation of piglet birth weight (BW0). Four batches of highly prolific crossbred Landrace × Large White sows were used. Three dietary treatments were compared: supplies of dextrose during the week before insemination (190 g/d) and of L-arginine (25.5 g/d) from d 77 of pregnancy until term (DEXA, n = 26); a dietary supplementation of L-arginine only (25.5 g/d), from d 77 of pregnancy until term (ARGI, n = 24); and no supplementation to a standard gestation diet (CTL; n = 23). Total born piglets (TB), i.e., piglets born alive (BA) and stillborn piglets, were numbered and weighed at birth and at weaning. Data were analyzed by ANOVA using the MIXED procedure in a model that included dietary treatment (ARGI, DEXA, and CTL), initial parity (1, 2 and 3, 4, and more), and backfat thickness (below or above the average value at the onset of the experiment: 15.7 mm) as the main effects and batch as random effect. The treatment did not influence (P > 0.10) the number of piglets at birth (on average 15.6 ± 3.8 and 14.2 ± 3.6 for TB and BA, respectively) or piglet BW0 (on average 1.48 ± 0.26 and 1.50 ± 0.26 kg for TB and BA, respectively). The coefficient of variation of piglet BW0 (CV(BW0)) was less in litters from ARGI sows than in litters from CTL sows and intermediate in litters from DEXA sows (for TB: 21.4, 23.4, and 25.7%, P = 0.08; for BA: 20.6, 22.5, and 25.4%, P = 0.03, in the ARGI, DEXA, and CTL groups, respectively). Irrespective of diet, CV(BW0) was less (P < 0.01) in litters with 16 TB piglets or less than in the largest litters (20.9 vs. 26.5%). Litter growth rate during lactation and litter size at weaning were not influenced (P > 0.10) by dietary treatments. In conclusion, supplementing gestation diet with L-arginine during the last third of pregnancy reduced within-litter variation of piglet birth weight. Combining L-arginine dietary supply with a supplementation of dextrose before insemination provided no additional benefit.

Post-insemination level of feeding does not influence embryonic survival and growth in highly prolific gilts.

This study was designed to investigate the influence of a high level of feeding during early gestation on embryonic survival and variability of embryonic development in hyperprolific LW gilts. During the 7 days after the first insemination, gilts were fed either 4 or 2kg daily of a gestation diet (groups High, n=15, and Control, n=13, respectively). Gilts were slaughtered at 27.0+/-0.1 days of pregnancy. Embryonic survival was 85.4+/-1.0% and the number of surviving embryos averaged 17.5+/-0.6. Embryos weighed 0.88+/-0.17g and measured 20.6+/-1.1mm, and within-litter variability in embryo weight averaged 11%. None of these criteria was significantly influenced by the level of feeding during the first week of pregnancy. Irrespective of nutritional treatment, embryonic survival was not related to ovulation rate or length of the uterine horns. Number of living embryos was not correlated with embryo weight and length. Within-litter variation in embryo weight or length was not correlated with the number of embryos or embryonic survival. In conclusion, a high level of feeding during early pregnancy of prolific gilts did not reduce embryo survival and had no beneficial nor detrimental effects on embryo size and variability at 27 days of gestation.

Yield and composition of milk from lactating mares: effect of body condition at foaling.

The yield and composition of milk from nursing mares were studied during the first 2 months of lactation in two groups of six and five saddle mares respectively made thin or fat before foaling, then fed ad lib. post partum. Milk yield did not significantly vary with body condition (16.5 and 15.4 kg/d for fat and thin mares respectively). Milk from fat mares had a higher fat content than milk from thin mares; the reverse was found for protein. The composition of milk fat was modified: milk of fat mares was poorer in short- and medium-chain fatty acids (C8-C14). Milk fat output was affected by body condition: 252 and 187 g/d for fat and thin mares respectively. This can be explained by a difference in lipid mobilization, as shown by variations in non-esterified fatty acids.

Voluntary intake, milk production and plasma metabolites in nursing mares fed two different diets.

Voluntary food intake, milk yield and composition, and blood metabolites were measured during the first 2 mo of lactation in draft broodmares fed diets containing either 95% hay and 5% concentrates (Diet F) or 50% hay and 50% concentrates (Diet C). Voluntary food intake was higher for mares fed Diet C than for those fed Diet F (22.9 vs. 21.4 kg dry matter in wk 4). Both diets, especially Diet C, were eaten in amounts exceeding the energy requirements. Daily milk yield in wk 4 was 26.4 kg and 23.4 kg for mares fed Diets C and F, respectively. Milk fat and protein concentrations were higher (P less than 0.01) for mares fed Diet F than for those fed Diet C and decreased (P less than 0.01) from colostrum (48 +/- 12 h after foaling to wk 8); lactose concentration was higher (P less than 0.05) for mares fed Diet C than for those fed Diet F and increased (P less than 0.01) from colostrum to wk 8. Minerals varied mainly with lactation stage. Milk fat was higher in linolenic acid and lower in linoleic acid for mares fed Diet F than for those fed Diet C. Glucose concentration was higher in plasma of mares fed Diet C; 3-hydroxybutyrate and acetate concentrations were higher in plasma of mares fed Diet F.

Yield and composition of milk from lactating mares: effect of lactation stage and individual differences.

The yields and composition of milk from nursing mares were studied during the first two months of lactation in 11 mares of heavy breeds (784 kg). Daily yield increased from 21.7 to 24.6 kg between weeks 1 and 8 of lactation. Fat, protein, gross energy and Ca concentrations significantly decreased when lactose content increased during this period. Individual variations were higher for yield than for composition. Casein, whey protein and non-protein N (56, 34 and 10% of crude protein, respectively) and amino acid composition did not vary between weeks 1 and 8 of lactation.

The use of urea as a marker of body water in the nursing foal.

Urea, compared with deuterium oxide (D2O) as a reference, was used as a body marker to estimate body water volume in ten 2-month old nursing foals. Plasma urea clearance was regular over 10 h and the R2 of the disappearance curve was between 0.93 and 0.98. Mean urea space was about 4% lower than D2O space, but the standard deviation of the proportion of water in body weight was higher with urea (3.8%) than with D2O (1.6%). Calculated urea entry rate was 49 mg/h/kg LW0.75.

Relationship between nutrient intake, growth and body composition of the nursing foal.

The milk and nutrient intakes of 21 nursing foals of heavy breeds (adult weight: 800 kg) were determined at 1, 4 and 8 weeks of age. Lactose intake increased (P is less than 0.01) from 1 300 g/day at 1 week of age to 1 800 g/d at 8 weeks; fat decreased (P is less than 0.01) from 400 g/d to 300 g/d and protein did not vary (600 g/d). Energy and nitrogen intakes did not depend on the source of energy in the mother's diet. Milk, energy and nitrogen intakes were well related (r = 0.74 to 0.81) with foal growth between 1 and 4 weeks, but not between 4 and 8 weeks. The composition of weight gain showed a greater deposition of protein than of lipids until 8 weeks. Lipid and protein contents in empty body weight were 5.3 and 19.2%, respectively, at 1 week and 9.0 and 19.9% at 8 weeks.