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The aim of this study was to evaluate ovarian follicular activity, ovulation percentage, and body weight change in response to focused nutrition during synchronization of oestrus with an intravaginal device (CIDR®) (9 days) in Pelibuey ewes with high and low body condition. Seventy-two non-pregnant ewes without offspring were randomly distributed to one of four treatments, namely T1: (n = 18) ewes without focused nutrition and low body condition; T2: (n = 18) ewes without focused nutrition and high body condition; T3: (n = 18) ewes with focused nutrition and low body condition; and T4: (n = 18) ewes with focused nutrition and high body condition. While the CIDR device was in place, the ewes with focused nutrition received a supplement of 1.5 kg ewe/day, which contained 2.9 MCal metabolizable energy, 16% crude protein, 88.5% dry matter, 11.8% crude fibre, and 6.7% of ash. The concentration of progesterone (P4) was measured to determine ovulation percentage. The follicular population was quantified (2-3 mm, 4-5 mm, and >6 mm in diameter). The number of follicles between 2-3 mm and 4-5 mm in diameter was similar among treatments. The number of follicles >6 mm in diameter was higher in T4 ewes (2.2 ± 0.2) compared with T1, T2, and T3. The response to oestrus, the onset of oestrus, and the ovulation percentage were similar among treatments. Focused nutrition increased the number of ovarian follicles >6 mm in diameter in ewes with high body condition. [ABSTRACT FROM AUTHOR]

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. Serum levels of cortisol, insulin and glucose were measured, in addition to heart rate (HR), respiratory rate (RR) and rectal temperature (RT). Effect of season x genotype interaction ( p ≤ 0.05) was observed in all COC variables and only in cleavage embryos (CLI) ( p ≤ 0.05). Body weight (BW) affected all COC variables ( p ≤ 0.01), except unviable (UNV) although affected degenerated embryos (DEG) ( p ≤ 0.01) and total blastocysts (BLAST) ( p ≤ 0.01). Cow age only affected viable COCs (VIAB) ( p ≤ 0.05), code one blastocysts (BC1) and BLAST ( p ≤ 0.01). Cortisol affected total COCs (COCsT), VIAB and total matured in vitro (TMIV) ( p ≤ 0.01), as well as CLI, BC1 ( p ≤ 0.01) and BLAST ( p ≤ 0.05). Insulin affected COCsT ( p ≤ 0.01), UNV ( p ≤ 0.05), denuded oocytes (DE) ( p ≤ 0.01), BC1 and code two blastocysts (BC2) ( p ≤ 0.01). Glucose affected all COC variables ( p ≤ 0.01), except UNV and all embryo variables except BC2. HR affected COCsT, DE, TMIV ( p ≤ 0.01), CLI, BLAST and DEG ( p ≤ 0.05). RR affected COCsT, UNV, VIAB, CLI ( p ≤ 0.05), BC1, BLAST and DEG ( p ≤ 0.01). RT only affected DE, VIAB ( p ≤ 0.01) and BLAST ( p ≤ 0.05). The seasonal climatic year variation of Veracruz and changes in physiological and hormonal variables have diverse effects on the cumulus-oocyte complexes and embryos produced by RM and TM donors.

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 ST ) 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. Two groups of ewes were identified to carry out the genetic comparison: with high fecundity (1.3 ± 0.03) and with low fecundity (1.1 ± 0.06). This study shows for the first time evidence of the influence of the CNOT11 , GLUD1 , GRID1 , MAPK8, and CCL28 genes in the fecundity of Katahdin ewes; in addition, new candidate genes were detected for fecundity that were not reported previously in ewes but that were detected for other species: ANK2 (sow), ARHGAP22 (cow and buffalo cow), GHITM (cow), HERC6 (cow), DPF2 (cow), and TRNAC-GCA (buffalo cow, bull). These new candidate genes in ewes seem to have a high expression in reproduction. Therefore, future studies are needed focused on describing the physiological basis of changes in the reproductive behavior influenced by these genes.

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 1 (weights recorded weekly from hatching to 63 d, and every 2 wk, from 63 to 133 d of age), DCP 2 (weights recorded weekly from hatching to 133 d of age), DCP 3 (weights recorded every third day, from hatching to 63 d, and every 14 d, from 63 to 133 d of age), and DCP 4 (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). For all growth models, the width of confidence interval (CI) of each parameter, was estimated (α = 0.05). The adjusted coefficient of determination (AR 2 ), as well as the Akaike (AIC) and Bayesian information criteria (BIC) were used to select the best model. The higher the AR 2 , and the lower the width of CI, as well as the AIC and BIC values, the better the model. The Gompertz-Laird model, more frequently showed the highest AR 2 , and the lowest AIC and BIC values compared to the other models. Moreover, for all models, both sexes and all parameters, most confidence interval widths (all with the Gompertz-Laird model) were the lowest with DCP 3 when compared to the other sets of data. In conclusion, the Gompertz-Laird model was the best provided that the chickens are weighed every third day from hatching until 63 d of age, and every 2 wk thereafter., Competing Interests: Disclosures The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the study reported., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

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 ( n = 8), where the lambs remained with their mothers; and (2) restricted suckling ( n = 8), where the mothers suckled their lambs twice daily for 30 min. On Day 19 postpartum, the ewes were individually penned with ad libitum access to water and feed and given an indwelling catheter in each jugular vein. On Day 20, 4 mL of blood was sampled every 15 min from 08:00 to 20:00 h to determine LH pulse frequency. At 14:00 h, four ewes in each group received 120 μg of kisspeptin diluted in 3 mL of saline as a continuous infusion for 6 h; the remaining four ewes in each group received only saline. The interaction between kisspeptin and suckling type did not affect LH pulse frequency ( p > 0.05). Before kisspeptin administration, pulse frequency was similar in all groups (1.50 ± 0.40 pulses per 6 h; p > 0.05). With the application of kisspeptin, pulse frequency increased to 3.50 ± 0.43 pulses per 6 h ( p ≤ 0.014), so the concentration of LH (1.11 ± 0.14 ng mL -1 ) was greater in kisspeptin-treated ewes than in saline-treated ewes (0.724 ± 0.07 ng mL -1 ; p ≤ 0.040). The frequency of LH pulses was greater with restricted suckling than with continuous suckling (2.44 ± 0.29 versus 1.69 ± 0.29 pulses per 6 h; p ≤ 0.040). We conclude that intravenous application of kisspeptin increases the pulsatile secretion of LH in suckling ewes and that suckling might reduce kisspeptin neuronal activity, perhaps explaining the suppression of ovulation. Moreover, the effects of kisspeptin and suckling on pulsatile LH secretion appear to be independent, perhaps operating through different neural pathways.

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 E 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. For this purpose, the quality of the sequences was analyzed and the polymorphisms and genotypes were searched for. The ewes were grouped according to their group: (a) homozygous or Embrapa (GG), (b) wild (AA), and (c) group without gene (sG). All the ewes studied manifested estrus behavior, but none showed signs of return to estrus after natural mating (p > 0.05); likewise, the pregnancy and lambing rates (p > 0.05) did not show differences between groups. However, the group GG presented higher ovulation rate, prolificacy, and fecundity rate (p < 0.05), compared to groups AA and sG. Although no differences were found in the manifestation of estrus, return to estrus, and percentage of pregnancy and lambing in females from the genotypes studied, the homozygous ewes GG presented 1.22 and 1.72 more corpus luteum (CL, p < 0.05), prolificacy of 0.7 and 0.7, and fecundity rate of 0.8 and 1.0 more lambs per ewe (p < 0.05) than the ones produced by the wild-type AA and sG groups, respectively.

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. Climatic data was used to define three seasons: hot-dry (HD), hot-humid (HH), and fresh-dry (FD), and 313 artificial insemination services from 176 heifers were analyzed over fourteen years. The seasons were determined by cluster analysis. Gestation at first service (GF) was analyzed with a logistic regression model and global gestation (GG) with a mixed linear generalized model. The Tmax of previous seven days insemination [Formula: see text] - 0.20 ± 0.09 (p ≤ 0.02) in HD (p ≤ 0.02) and RH of seven days posterior insemination [Formula: see text]= - 0.08 ± 0.04 (p ≤ 0.04) in HD (p ≤ 0.01) affected GF. No effect of the Tmax and RH on the service day was observed (p > 0.05). The highest GG probabilities were higher than 0.70 in HH and FD, making those seasons the most suitable for inseminating LT heifers.

Mycobacterium avium subsp. paratuberculosis (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. The aim of the study was to identify the presence of MAP in reproductive tissue and semen of infected Pelibuey rams in clinical state of PTB. Seven rams were used in clinical PTB state and a non-infected ram by MAP of the Pelibuey breed, confirmed by serology, nPCR and bacteriological culture, with average weight and age of 57.23 ± 1.73 kg and 2.91 ± 0.17 years, respectively. The presence of MAP was identified in different tissue samples: spleen (1/7, 14.3% and 2/7, 28.6%), small intestine (3/7, 42.9% and 4/7, 57.1%) and mesenteric lymph nodes (3/7, 42.9% and 3/7, 42.9%), with nPCR and culture, respectively. It was also identified in epididymis tissue (1/7, 14.3%), Cowper gland (2/7, 28.6%) and prostate (1/7, 14.3%), using nPCR, although without detection in culture. It was identified in testicular tissue in 42.8% (3/7; culture or nPCR technique), but in 28.6% (2/7) with both techniques. Finally, the presence of MAP was identified in 42.9% (3/7) of semen samples with nPCR; however, it was not detected through culture. In conclusion, the presence of MAP was identified in lymphatic, digestive tissue, and semen; the presence of MAP was reported for the first time in epididymis, Cowper gland, prostate and testicles of infected Pelibuey rams., Competing Interests: Conflicts of interest: The authors have no conflict of interest to declare., (Copyright © The Author(s).)

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. In all the analyzed characteristics, the best results were obtained in WE. Within the WE group, the best treatment (P<0.05) was T1 with 85.7% of the ewes in oestrus, 71.4% pregnant and a prolificacy of 1.9. Within the WRS group the best results were observed in T1. In both groups, the lowest results (P<0.05) were obtained in T4. In Experiment 2, 75 ewes were randomly assigned to one of three groups (n=25) immediately after parturition: Group 1, Without restriction of suckling (WRS, as in Experiment 1); Group 2, with restriction of suckling (RS; suckling for 30 min day(-1)); Group 3, Early Weaning (EW: at 7 days pp). All ewes were given PGF2alpha at 30 days pp and the same hormonal treatment, FGA for 12 days+PGF2alpha and eCG 2 days before removing FGA. No differences were observed (P>0.05) between RS and EW for the presentation of oestrus (96% vs. 92%), pregnancy (72% vs. 76%) or prolificacy (1.9 vs. 1.9), although group WRS did not perform (P<0.05) as well as groups RS and EW for any measure of performance. In conclusion, the combination of hormonal treatment (FGA plus eCG) with weaning at 7 or 40 days pp, or restricted suckling, improves postpartum reproductive efficiency in Pelibuey ewes, demonstrating the inhibitory role of suckling on postpartum reproduction in this breed.

The seasonality of reproductive activity in the ewe in temperate latitudes is controlled by photoperiod. Its annual variations control the temporal organization of the sexual cycle by changing the activity of the gonadotrophic axis. Cyclic oestrous behaviour usually appears in the ewe at the end of summer or the beginning of autumn and finishes in winter or at the very beginning of spring. Seasonal anoestrus is characterized by the absence of ovulation and sexual behaviour. During seasonal anoestrus, a decrease in LH pulse frequency is observed. The inhibition of pulsatile LH secretion is maintained throughout the anoestrous season and is responsible for the low reproductive activity during this period. Variation in the seasonal inhibition of LH pulsatility results from an increase in the negative feedback by oestradiol on LH pulse frequency during the long days of spring and summer. The inhibition of LH secretion involves increased action of dopamine in the hypothalamus on the chain of nervous elements which controls gonadotrophic activity. Among the various dopaminergic structures, the retrochiasmatic A15 nucleus is involved in the inhibitory control of LH pulsatility by oestradiol during the long day period. Oestradiol increases the dopaminergic tone of the A15 nucleus in ovariectomized ewes during the long day period. In this structure, the effect of oestradiol on the dopaminergic metabolism probably results from a direct, local activation. In the sheep, dopamine might also participate in the inhibition of gonadotrophin activity during other periods of reproductive life.