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The aim of this study was to evaluate the effect of the month of oocyte harvesting and the temperature–humidity index on oocyte number and quality harvested from Holstein cows and heifers, oocyte developmental competence, and total embryos produced in an area of intense ambient temperature for most of the year. A total of 5064 multiparous lactating cows and 2988 nulliparous heifers were used as oocyte donors and distributed across the months of the year. Overall, total oocytes per collection did not differ (p > 0.05) between cows (16.6 ± 2.7) and heifers (15.1 ± 1.8), but oocyte developmental competence was lower (p < 0.05) in cows (21.3 ± 5.4) than heifers (25.5 ± 4.0). For cows, the total number of oocytes harvested was two-fold higher (p < 0.05) in November than in May. For heifers, the total number of oocytes harvested was highest in April (17.19 ± 0.53) and lowest in May (10.94 ± 0.32; p < 0.05). For cows, total embryos were highest in November (2.58 ± 0.42) and lowest in August (1.28 ± 0.10; p < 0.05). Thus, taken together, these results indicate that severe heat stress impaired the number and quality of oocytes harvested from donor Holstein multiparous cows and heifers, oocyte developmental competence, and total embryos produced in this area of intense ambient temperature for most of the year.

This research aimed to evaluate whether the administration of hCG at the time of removal of a progesterone device may be effective at inducing estrus and ovulations in sheep during the natural seasonal anestrous, by comparing reproductive outputs (induction and duration of estrus, follicle development, ovulation, ovulation rate, and pregnancy rates) in ewes treated with eCG or only saline solution at the time of CIDR removal. Whereas results demonstrated no response in the control non-treated group, the largest rate of narrowly synchronized estrus signs and ovulations occurred in the eCG-group. The administration of hCG was effective at inducing estrus, promote follicular growth and a delayed yet significant ovulation (>84%) on day 10 after CIDR removal; moreover, an increased embryonic implantation rate was also observed. Moreover, if the hCG ewes remain exposed to active males for some days, said strategy could be adopted, aiming to induce pregnancies by natural mating in a short period of time.

The possible role of the social rank (R) (i.e., low-LSR, middle-MSR, or high-HSR) in anestrus goats exposed to a P4 + eCG (D) (i.e., 100 or 350 IU) estrus induction protocol (EIP) was evaluated. Goats (Alpine-Saanen-Nubian × Criollo; n = 70; 25° North) managed under stall-fed conditions were all ultrasound evaluated to confirm anestrous status, while the social rank was determined 30 d prior to the EIP. The response variables included estrus induction (EI, %), duration of estrus (DUR, h), ovulation rate (OR, n), live weight (LW, kg), thoracic perimeter (TP, cm), thoracic diameter (TD, cm), body length (BL, cm), height at withers (HW, cm), beard length (BEA, cm), compactness index (COM, cm), and anamorphosis index (ANA, cm), as affected by R, D, and the R × D interaction were evaluated, while the correlation coefficients among reproductive and morphometric variables were quantified. An R × D interaction (p < 0.05) affected the response variables EI, DUR, and OR. While the largest (p < 0.05) EI% occurred in the HSR goats, irrespective of eCG (i.e., 100 or 350 IU), both the shortest estrus duration (DUR, h) and the lowest ovulation rate (OR, n) occurred in the LSR + D100 combination, with no differences among HSR and MSR either with D100 or D350. Regarding the LW and morphometric response variables, (i.e., LW, TP, TD, BL, HW, BEA, COM, and ANA) all of them favored either the HSR and MSR groups, with the lowest phenotypic values occurring in the LSR-goats. The EI% was observed to be positively correlated (p < 0.05) with DUR (0.71), LW (0.28), TP (0.31), TD (0.34), BL (0.33), HW (0.35), COM (0.23), and ANA (0.23). While DUR was correlated (p < 0.05) with TP (0.26) and ANA (0.24), OR demonstrated no-correlation (p > 0.05) with any response variable, either reproductive or morphometric. As expected, LW had high correlation coefficients (p < 0.01) with TP (0.86), TD (0.88), BL (0.82), HW (0.75), BEA (0.51), COM (0.97), and ANA (0.75). In general, the morphometric variables as a whole demonstrated important correlation coefficients among them (p < 0.01), ranging from 0.38 up to 0.84. To estimate the importance of the morphometric differences between social rank upon estrus induction, a principal component (PC) analysis was performed based on the correlation matrix derived from the corporal measurements. The PC1 and PC2 explained 70.3% and 17.6% of the morphometric variation, respectively. The PC1 was a measure of the goat size (i.e., small, medium, large) and its association with estrus occurrence was evaluated using a logistic regression model; the bigger the goat, the increased probability of being in estrus, by up to five times compared to small goats. Our results confirm that the higher social ranked, larger goats amalgamated some fundamental factors to be successful: aggressiveness, primacy to food access, augmented live weight, and corporal size; all of these were able to modulate out-of-season reproductive success in crossbred dairy goats subjected to an estrus induction protocol and managed under stall-fed conditions in Northern Mexico.

Seasonal reproduction restricts the offering of goat commodities across the year. Therefore, it is crucial to improve diverse strategies to induce the reproductive response in goats during the anestrus stage. The effectiveness of a short P4 + eCG-based estrus induction protocol during both the deep anestrous (March) or the reproductive transition period (June) upon the reproductive performance of crossbred dairy goats was assessed. Adult, anestrous, 24–30-month- old dairy crossbred (Saanen–Alpine–Nubian × Criollo) goats (n = 123) from two commercial herds and 10 sexually active goat bucks were used. Before the trials, the anestrous status of goats was confirmed. Then, goats were randomly allocated into two different experiments. In Exp. 1, we tested the effect of different doses (D) of intramuscular progesterone (P4; 10 or 20 mg + eCG (100 UI)) and type of breeding (TB), natural mating (NM), or artificial insemination (AI), on two commercial goat herds (H1 & H2), in March (deep anestrous). In Exp. 2, we evaluated the effect of D (P4; 10 or 20 mg + 100 UI eCG) in goats subjected to NM, and either during deep anestrous (March; M) or transitional anestrous (June; J), in two commercial herds. After breeding, conception and pregnancy were diagnosed with ultrasound scanning. The response variables were estrus induction (EI; %), estrus latency (EL; h), ovulation (OVP; %), ovulation rate (OR; units), fertility (FERT; %), and pregnancy (PREG; %). No differences (p > 0.05) in live weight (LW) and body condition score (BCS) occurred between herds in both trials. In Exp. 1, EI, EL, OVP, OR, FERT, and PREG were affected (p < 0.05) by the H–TB–D interaction, whereas in H1 + P4–20 combination had the highest (p < 0.05) EI, EL, and OVP values. Irrespective of TB, H1 had the largest (p < 0.05) OR, independently of TB or D. Also, the lowest (p < 0.05) OVP occurred in the AI + P4–10 group, while the AI had the lowest (p < 0.05) FERT, irrespective of D. FERT and PREG were two-fold higher (p < 0.05) in NM compared with AI. In Exp. 2, EI, EL, OVP, OR, FERT, and PREG were affected (p < 0.05) by the H–M–D interaction. In general, H2 + P4–10 had the lowest (p < 0.05) reproductive outcomes in March, whereas H1 had the largest (p < 0.05) values in either month. No differences (p > 0.05) between P4 doses occurred for EI, OVP, OR, FERT, and PREG. Yet, the largest (p < 0.05) EL occurred with P4–20 in June. No correlations (p > 0.05) occurred between LW and all the reproductive variables. BCS was positively correlated (p < 0.05) with EI (0.34), OVP (0.44), OR (0.58), and PREG (0.20). Also, positive correlations (p < 0.05) occurred between EI with EL (0.83), OVP (0.80), OR (0.64), and PREG (0.56); EL with OVP (0.58), OR (0.44), and PREG (0.42); OVP with OR (0.79) and PREG (0.70), as well as OR and PREG (0.63). Results of these studies confirm a multidimensional response regarding the effectiveness of P4 + eCG for estrus induction in goats mainly modulated by a specific time within the anestrous season, or even by specific management or a particular environment at the herd level (H1), although quite remarkably independent of the animal’s LW or BCS at herd level. Moreover, the best reproductive outcomes occurred with NM in June. The most reproductive variables were similar using either 10 or 20 mg P4 + 100 IU eCG, giving the possibility to lessen the scale in the use of exogenous hormones while obtaining acceptable out of season reproductive response.

The possible effect of protein-enriched Opuntia cladode supplementation during the pre- and post-partum stages (−25 days to +15 days; day 0 = kidding) upon dam–kid metabolic status, colostrum-milk quality, and some behavioral kid-to-dam interaction in goats managed under rangeland extensive conditions was evaluated. Multiparous crossbred goats (n = 30), homogeneous regarding live weight (LW; 55.9 ± 1.03 kg) and body condition score (BCS; 2.5 ± 0.2 units), were randomly assigned to (1) protein-enriched Opuntia (PEO; n = 10; 29.8% crude protein (CP), 2.2 Mcal ME kg−1), (2) non-enriched Opuntia (NEO; n = 10; 6.4% CP, 2.1 Mcal ME kg−1), and (3) control (CON; n = 10, non-supplemented). The PEO and NEO goats were individually supplemented with Opuntia cladodes (250 g day−1; 09:00–10:00 a.m.; 25 days pre- and 15 days post-partum); then, all groups grazed in a marginal rangeland (10:00 a.m. to 06:00 p.m.). LW, BCS, and blood samples to quantify serum glucose (GLU) levels were collected weekly from day −25 up to day +15 in both dams (pre- and post-partum) and kids (post-partum). At 4 h and 8 h post-partum, kid-to-dam behavioral tests were performed; approaches (APRO, units), animal-to-animal contact (ACONT, s), latency-to-contact (LCONT, s), and high (HPB) and low (LPB) bleats were registered. The response variables LW (58.2 ± 3.5 kg), GLU from does (66.4 ± 3.3 mg/dL), colostrum fat (12.3 ± 1.15%), non-fatty solids (20.9 ± 2.1%), density (64.4 ± 7.0%), and protein (8.1 ± 0.8%), as well as milk density (31.2 ± 1.7%) and protein (3.9 ± 0.3%), favored the PEO group. Moreover, the dam-to-kid 4 h LPB (34.5 ± 4.6 frequency), as well as kid-to-dam 8 h LCONT-own (100 ± 35.5 s) and LPB (25.2 ± 6.9 frequency) also favored the PEO group. To conclude, peripartum supplementation with protein-enriched Opuntia cladodes emerged as a key alternative to enhance the dam–kid metabolic status, to improve colostrum quality and some milk components (density and protein), as well as to expand the kid-to-dam bond in goat production systems under marginal extensive conditions.