In Vitro Embryos of Romosinuano and Tropical Milking Cattle during Three Seasons in Veracruz, Mexico.

One of the main factors that influences the fertility of cattle in grazing systems in hot tropical climates is heat stress. The objective of this study was to evaluate the effect of season, breed, hormonal and physiological condition on the quantity and quality of cumulus-oocyte complexes (COCs) and embryos produced in vitro, from Romosinuano (RM) and Tropical Milking (TM) donors. Three ovum pick-up and in vitro fertilization (OPU-IVF) were performed, one per season: hot dry (HD; 10, 10), hot humid (HH; 9, 9) and fresh dry (FD; 7, 10) in RM and LT donors.

Detection of Candidate Genes Associated with Fecundity through Genome-Wide Selection Signatures of Katahdin Ewes.

One of the strategies to genetically improve reproductive traits, despite their low inheritability, has been the identification of candidate genes. Therefore, the objective of this study was to detect candidate genes associated with fecundity through the fixation index (F) and runs of homozygosity (ROH) of selection signatures in Katahdin ewes. Productive and reproductive records from three years were used and the genotypes (OvineSNP50K) of 48 Katahdin ewes.

Mexican Creole chickens: effect of data collection periods on goodness-of-fit and parameter precision of growth models.

The objective of this study was to estimate the good-of-fitness and precision of parameters of the Gompertz-Laird, Logistic, Richards, and Von Bertalanffy growth models, using different data collection periods (DCP). Two hundred and sixty-two Mexican Creole chicks (116 females and 146 males), were individually weighed to form the following sets of data for each sex: DCP (weights recorded weekly from hatching to 63 d, and every 2 wk, from 63 to 133 d of age), DCP (weights recorded weekly from hatching to 133 d of age), DCP (weights recorded every third day, from hatching to 63 d, and every 14 d, from 63 to 133 d of age), and DCP (weights recorded every third day, from hatching to 63 d, and weekly, from 63 to 133 d of age). Data were analyzed using the NLIN procedure of SAS (Marquardt algorithm).

Kisspeptin Stimulates the Pulsatile Secretion of Luteinizing Hormone (LH) during Postpartum Anestrus in Ewes Undergoing Continuous and Restricted Suckling.

This study tested whether the intravenous application of kisspeptin can stimulate the pulsatile secretion of LH in suckling ewes during postpartum anestrus. Ten days after lambing, Pelibuey ewes were allocated among two groups: (1) continuous suckling ( = 8), where the lambs remained with their mothers; and (2) restricted suckling ( = 8), where the mothers suckled their lambs twice daily for 30 min. On Day 19 postpartum, the ewes were individually penned with access to water and feed and given an indwelling catheter in each jugular vein.

Influence of FecG mutation on the reproductive variables of Pelibuey ewes in the anestrus period.

The growth and differentiation factor 9 (GDF9) intervenes in the fecundity and prolificacy of the ewe, which are important variables that participate in the reproductive efficiency of a flock. The objective of this study was to evaluate the influence of FecG mutation of the gene GDF9 in the natural response of the manifestation to estrus, return to estrus, ovulation rate, pregnancy, lambing, prolificacy, and fecundity rate in Pelibuey ewes, during the anestrus period. The sequences of the exon 2 of the gene GDF9 were obtained from blood samples collected in Whatman™ FTA™ cards from 42 multiparous Pelibuey ewes with reproductive records.

Relation of the maximum temperature and relative humidity close to the insemination with the tropical milking criollo heifer's gestation in three seasons.

The high climatic variability of hot climates of the intertropical zone reduces cattle fertility. In dairy cows in temperates zones, the THI has been used to evaluate the temperature and relative humidity (RH) joint effect in reproduction, but its use is not recommended in all geographic zones; in hot climates, the maximum temperature (Tmax) can provide more convenient information than THI. The objective of this study was to determine the artificial insemination (AI) service seasons and their joint effect with the maximum temperature and relative humidity of the previous seven days, the service day, and posterior seven days to the AI in the tropical milking criollo (LT) heifer's gestation.

Effect of temperature - humidity index on the onset of post- partum ovarian activity and reproductive behavior in cows.

The effect of climatic factors on ovarian activity and reproductive behavior (RB) was evaluated in 46 cows kept under grazing conditions. Temperature-humidity index (THI) was used as an indicator of stress and divided in alert, damage and emergency levels. Fat thickness (FAT) was taken during the last trimester of gestation (LTG) to approximately 90d postpartum (PP).

Detection of subsp. in reproductive tissue and semen of naturally infected rams.

subsp. (MAP) is the causative agent of paratuberculosis (PTB), disease that causes a syndrome of bad nutrient absorption, weight loss and eventually death. The intestine is the main target organ where the infection develops; however, there is evidence of infection by MAP in extra-intestine sites of sheep, including mesenteric nodes and semen.

Prevention of suckling improves postpartum reproductive responses to hormone treatments in Pelibuey ewes.

To determine the effects of suckling on postpartum (pp) reproductive efficiency in Pelibuey ewes, two experiments were performed. In Experiment 1, 112 ewes were randomly assigned to one of two groups at parturition: Without restriction of suckling (WRS) 24 h day(-1) for 60 days (n=56), and Weaned Ewes (WE), weaned at 40 days pp (n=56). On Day 30 pp, all ewes were given Prostaglandin (PGF2alpha) and one of four treatments (n=14): T1, intravaginal progestagen (FGA; 40 mg) for 12 days from day 30 pp+equine chorionic gonadotropin (eCG; 300 UI) until 2 days before removing FGA; T2, FGA was applied for 12 days; T3, a second application of PGF2alpha was given on day 40 pp+eCG on the same day; T4, a second injection of PGF2alpha was applied on day 40 pp only.