Genotyping of rams based on melatonin receptor 1A gene polymorphisms: a tool in sire selection?

Context Several polymorphisms in the melatonin receptor 1A gene (MTNR1A ) have been related to reproductive performance in ovine. Aims To investigate the effect of the Rsa I and Mnl I polymorphisms on ram seminal quality. Methods Eighteen Rasa Aragonesa rams were genotyped for the Rsa I (C/C, C/T, T/T) and Mnl I (G/G, G/A, A/A) allelic variants of the MTNR1A gene. Individual ejaculates were analysed once a month throughout the whole year. Sperm motility, morphology, membrane integrity, levels of reactive oxygen species (ROS), phosphatidylserine (PS) inversion, DNA fragmentation and capacitation status were assessed. The effect of the season and polymorphisms on seminal quality was evaluated by mixed ANOVA. Key results Both polymorphisms had an effect on membrane integrity and viable spermatozoa with low levels of ROS and without PS translocation, and Rsa I also on motile and DNA-intact spermatozoa. An interaction between both polymorphisms was found, pointing to a negative effect on seminal quality of carrying the T or A allele in homozygosity. Differences were higher in the reproductive than in the non-reproductive season. Conclusions Mutations substituting C by T and G by A at Rsa I and Mnl I polymorphic sites, respectively, in the MTNR1A gene in rams could decrease the seminal quality. Implications Genotyping of rams based on melatonin receptor 1A could be a powerful tool in sire selection.

Long-term effects of early maternal undernutrition on the growth, physiological profiles, carcass and meat quality of male beef offspring.

The effects of maternal undernutrition in early gestation on growth, metabolic and endocrine profiles, carcass and meat quality of male offspring in cattle were assessed. Twenty-one Parda de Montaña and 14 Pirenaica cows received a CONTROL (100% nutrition requirements) or a SUBNUT (65%) diet from day 0 to 82 of gestation and thereafter were fed to requirements until calf weaning at 4 months of age. The performance and physiological profiles of male offspring during an 8-month fattening period were analyzed. Bulls were slaughtered at 12 months of age, and their carcasses and meat color, tenderness and intramuscular fatty acid profile were evaluated. Maternal undernutrition increased plasma NEFAs and impaired the growth of Pirenaica bulls, resulting in lower weights at slaughter and fatter carcasses with impaired meat tenderness. Irrespective of the breed, maternal undernutrition affected meat color and increased the meat content of some healthy fatty acids. In summary, early maternal undernutrition affected the fetal programming of beef male offspring with persistent consequences at slaughter.

Effects of an anti-gonadotrophin releasing hormone vaccine on the morphology, structure and function of bull testes.

Castration reduces aggressive and sexual behaviour and provides better carcass quality in bull calves. Vaccination against gonadotrophin-releasing hormone (GnRH) is used as an alternative to surgical castration for the purposes of reducing pain and distress in the animals. Currently, no anti-GnRH vaccine has been authorized for use in cattle in the European Union. The aim of the present study was to assess the effect of an anti-GnRH swine-specific vaccine (Improvac®, Zoetis, USA) on the morphology, structure and function of bull testes. Animals were vaccinated at days 1, 21 and 104 of the experimental period and were classified based on their live weight into the following two groups: LIGHT (172.9 ±â€¯30.00 kg) and HEAVY (323.8 ±â€¯37.79 kg). The scrotal circumference was measured on day 1 and prior to slaughter (day 164). At slaughter, the sperm motility and concentration in the caudae epididymis were assessed. Testes were weighed, measured and examined using ultrasound, and then tissue samples were collected and fixed in formalin. Histological and immunohistochemical studies were performed on the testes to measure the diameter of the seminiferous tubules and assess the testicular cell populations. The results revealed that suppression of testicular development was associated with the use of the Improvac® vaccine, which resulted in a smaller size of the testes and impaired spermatid production. However, the effect of Improvac® was more pronounced and consistent in calves vaccinated at a low live weight than at a heavy live weight, which suggested that vaccination is more effective when calves are vaccinated before or early during puberty. However, testes from calves vaccinated at a low live weight were more prone to the development of intraluminal concretions in the seminiferous tubules.

Effects of immunocastration performed at two live weights on the growth physiology, temperament and testicular development of feral beef bulls.

The aim of this study was to examine the effect of administering an anti-gonadotropin-releasing hormone vaccine (Improvac® , developed for pigs) on the performance, temperament, testicular development, and hormone and metabolite profiles of feral bulls (Bos taurus) vaccinated at two different live weights (LW). In all, 16 Serrana de Teruel animals were involved in this 2 x 2 factorial design using the factors LW (LIGHT vs. HEAVY) and vaccine treatment (control, C vs. vaccinated, VA). All animals received the same diet (ad libitum concentrate plus straw) over a 164-day fattening period. Temperament was assessed using chute and flight speed tests. Testicular diameter and subcutaneous fat thickness were recorded. Testosterone, IGF-1, urea, NEFA, and creatinine profiles were analyzed. Bull weight gain was reduced in VA compared to C animals, regardless of the initial LW. The vaccine did not affect the temperament tests, subcutaneous fat thickness or NEFA and creatinine concentrations and had minor effects on linear body measures. The vaccine inhibited testicular growth, reduced plasma testosterone to residual levels, and increased urea concentrations. LIGHT-C animals exhibited increased mean plasma IGF-1 concentrations compared to LIGHT-VA animals. In conclusion, vaccination reduced bull growth and sexual development irrespective of LW at immunization.

Effects of Developmental Programming Caused by Maternal Nutrient Intake on Postnatal Performance of Beef Heifers and Their Calves.

In this study, we evaluated the effects of maternal subnutrition in early pregnancy on the growth and reproductive performance of female offspring during their rearing, first gestation, and lactation. We inseminated 21 Parda and 15 Pirenaica multiparous cows and assigned them to a CONTROL (100% of nutrition requirements) or SUBNUT (65%) diet until day 82 of gestation. Cows were fed 100% requirements afterward. During the rearing of female offspring, growth, physiological profiles and ovarian follicular dynamic were studied. At 16 months old, heifers were inseminated. After first calving, dam-calf weights were recorded during lactation. Heifers born from CONTROL cows were heavier at weaning (four months old) than heifers born from SUBNUT cows, but this difference disappeared at the end of rearing and during the first gestation and lactation periods. All heifers reached puberty at a similar age and live weight. During rearing, SUBNUT heifers had higher concentrations of non-esterified fatty acids, urea, and cholesterol and a lower antral follicle count than CONTROL, but no difference was found in their fertility rate. After heifer first calving, dam-calf weights were similar among groups. In conclusion, maternal undernutrition reduced offspring postnatal gains at weaning, compromising metabolic status and follicle population during rearing but did not impair performance in the first gestation and lactation periods of beef heifers.

Long-Term Effects of Maternal Subnutrition in Early Pregnancy on Cow-Calf Performance, Immunological and Physiological Profiles during the Next Lactation.

This study aimed to evaluate the effects of undernutrition during the first third of gestation on cow-calf performance, immunological and physiological profiles during the next lactation in two cattle breeds. Fifty-three Parda de Montaña (PA) and 32 Pirenaica (PI) cows were inseminated, assigned to one of two diets (CONTROL or SUBNUT; 100% or 65% of their requirements) until day 82 of gestation, and fed 100% of the requirements during gestation and next lactation. Cow and calf performance were assessed during lactation. Colostrum and cow-calf plasma samples were analyzed to assess the passive transfer of immunoglobulins and to characterize energy metabolism. At calving, SUBNUT cows had a lower body condition score, which impaired most of the cow-calf parameters. All cows had considerable weight losses during lactation except for SUBNUT-PI cows. Colostrum immunoglobulin G (IgG) concentration was lower in SUBNUT-PI cows, and milk fat content was higher in SUBNUT cows. SUBNUT calves had lower values of body measurements at weaning, and calves born from SUBNUT-PI dams had lower milk intake and the lowest average daily gain (ADG), which was reflected in their lower plasma insulin-like growth factor-1 (IGF-1) concentration. In conclusion, undernutrition in early gestation in suckler cows had long-term effects on offspring postnatal growth, this physiological evidence being more severe in Pirenaica cow-calf pairs.

Effects of maternal subnutrition during early pregnancy on cow hematological profiles and offspring physiology and vitality in two beef breeds.

This experiment evaluated the effects of subnutrition during early gestation on hematology in cows (Bos Taurus) and on hematological, metabolic, endocrine, and vitality parameters in their calves. Parda de Montaña and Pirenaica dams were inseminated and assigned to either a control (CONTROL, 100% requirements) or a nutrient-restricted group (SUBNUT, 65%) during the first third of gestation. Dam blood samples were collected on days 20 and 253 of gestation, and calf samples were obtained during the first days of life. Pirenaica dams presented higher red series parameters than Parda de Montaña dams, both in the first and the last months of gestation. During early pregnancy, granulocyte numbers and mean corpuscular hemoglobin were lower in Pirenaica-SUBNUT than in Pirenaica-CONTROL cows. Calves from the SUBNUT cows did not show a physiological reduction in red series values in early life, suggesting later maturation of the hematopoietic system. Poor maternal nutrition affected calf endocrine parameters. Newborns from dystocic parturitions showed lower NEFA concentrations and weaker vitality responses. In conclusion, maternal nutrition had short-term effects on cow hematology, Pirenaica cows showing a higher susceptibility to undernutrition; and a long-term effect on their offspring endocrinology, SUBNUT newborns showing lower levels of IGF-1 and higher levels of cortisol.