Effect of Social Rank upon Estrus Induction and Some Reproductive Outcomes in Anestrus Goats Treated With Progesterone + eCG

We evaluated 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). Adult, multiparous (two to three lactations), multiracial, dairy-type goats (Alpine-Saanen-Nubian x Criollo goats (n = 70; 25°51' North) managed under stall-fed conditions were all ultrasound evaluated to confirm anestrus status while the R was determined 30 d prior to the EIP. The variables of estrus induction (EI, %), estrus latency (LAT, h), estrus duration (DUR, h), ovulation (OVU, %), ovulation rate (OR, n), corpus luteum size (CLS, cm), pregnancy (PREG, %), kidding (KIDD, %), and litter size (LS, n) as affected by R, D, and the R × D interaction, were evaluated. While OVU and CLS favored (p < 0.05) HSR (96% and + 1.04 ± 0.07 cm), an increased (p < 0.05) LS occurred in D350 vs. D100 (2.06 ± 0.2 vs. 1.36 ± 0.2); neither R nor D affected (p > 0.05; 38.5%) KIDD. However, EI, LAT, DUR, OR, and PREG were affected by the R × D interaction. The HSR group had the largest (p < 0.05) EI % and DUR h, irrespective of D. The shortest (p < 0.05) LAT occurred in D350, irrespective of R. While the largest (p < 0.05) OR occurred in HSR and MSR within D350, the HSR + D350 group had the largest PREG (p < 0.05). These research outcomes are central to defining out-of-season reproductive strategies designed to attenuate seasonal reproduction in goats.

The Opuntia effect and the Reactivation of Ovarian Function and Blood Metabolite Concentrations of Anestrous Goats Exposed to Active Males

Simple Summary

We evaluated the potential supplementation effect of protein enriched Opuntia cladodes, the flat leaf-like steam of cactus species (PEO), upon changes of blood metabolites, estrus induction, estrus latency, and ovulation rate in anestrous goats exposed to sexually active males. We observed that PEO positively influenced reproductive outcomes without changes in blood metabolites. Our results highlight the importance that bio-fortified Opuntia cladodes supplementation exerts on anestrous goats exposed to the male effect as an option to improve not only the out-of-season reproductive efficiency of goats but to enhance the sustainability of marginal, extensive and semi-arid goat production systems.

Abstract

The effect of protein enriched Opuntia cladodes supplementation upon changes of serum total protein, urea, cholesterol, glucose as related to estrus induction (EI%), estrus latency (EL, h), and ovulation rate (OR, units) in adult anestrous goats exposed to the male effect was evaluated. In late April, anestrus goats (n = 45, 25° N) homogeneous regarding live weight (LE; 43.8 ± 1.6 kg) and body condition score (BCS; 2.3 ± 0.1 units) were randomly assigned to: (1). Protein-enriched Opuntia (PEO; n = 15; 29.8% CP, 2.2 Mcal ME kg⁻¹), (2). Non-enriched Opuntia (NEO; n = 15; 6.4% CP, 2.1 Mcal ME kg⁻¹), and (3). Control (CON; n = 15). NEO and PEO goats were individually supplemented with cladodes (160 g d⁻¹; 0900–1000 h), thereafter all groups grazed in a marginal rangeland (1000–1800 h). Neither LW (p > 0.05) nor BCS (p > 0.05) differed among groups, yet an increased (p < 0.05) EI % (100, 57, 42 ± 0.16%), EL h (62, 60, 32 ± 4.2 h), and OR (1.33, 0.71, 0.43 ± 0.23 units) occurred in PEO and NEO vs. CONT, respectively. However, neither blood metabolites differed among groups nor a treatment x time interaction occurred. Peri-breeding protein enriched Opuntia cladodes supplementation of anestrous goats exposed to active males increased (p < 0.01) reproductive outcomes during the non-breeding season.

Physicochemical characterization of goat milk produced in the Comarca Lagunera, Mexico

The purpose of this study was to determine goat milk physicochemical parameters during the feed scarcity season. An evaluation was made for 398 milk samples from 80 multiparous goats belonging to three different production systems: (S1) mechanized milking grazing pasture and harvested residue (alfalfa) and grain supplemented; (S2) system grazing native pasture; and (S3) system grazing native pasture and grain supplemented. The general averages were: fat (FT) 4.0 ± 0.20%, protein (PR) 3.3 ± 0.05%, lactose (LC) 4.9 ± 0.09%, nonfat solids (NFS) 8.9 ± 0.13%, total solids (TS) 14.5 ± 0.20%, temperature (TM) 24.6 ± 1.06°C, and acidity (pH) 6.7 ± 0.049. Most of the physicochemical components of milk were affected (p < 0.0001) by the production system × month interaction and production system × group × month interaction. The FT content was higher (p < 0.05) in S2 (4.56 ± 0.18) than in S1 (3.64 ± 0.20) and S3 (3.50 ± 0.20). LC differed (p < 0.05) in S2 (5.07 ± 0.08) than in S1 (4.77 ± 0.09) and S3 (4.70 ± 0.09). No differences were observed for the rest of the variables (p < 0.05) among the production systems. The study unveiled a higher content of FT, LC, NFS, PR, and TS for S2 than for S1 and S3. This higher content may be explained because S2 only grazed on herbs and shrubs, in contrast to S1 and S3 which were additionally supplemented with grain concentrates.

The use of female estrogenized goats as sexual stimulator of crossbred dairy males subsequently exposed to acyclic goats during two phases of the anestrous season

This research evaluated the possible influence of exposure of male goats to estrogenized female goats ("female effect") upon males' sexual behavior [appetitive (ASB) & consummatory (CSB)], as well as the induction of reproductive activity of crossbred dairy female goats exposed to such treated males ("male effect") during the early and deep anestrous periods. Crossbred dairy adult male goats (n = 12; 24-48 mo. old) and 80 anovulatory crossbred dairy adult female goats (34-50 mo. old) were used during two experimental periods: March to April and April to May. First, males were separated into four groups (n = 3 each), roughly homogeneous regarding body weight and body condition score and randomly assigned to four experimental groups. The first two groups included males + estrogenized females, then such males were exposed to anestrous females either during March (group 1: three males; 20 females; EFEM-MAR), or during April (group 2: three males; 20 females; EFEM-APR). The second two groups were respective control groups: Males + non-treated-anestrous females, and then such males exposed to acyclic females either during March (group 3: three males; 20 females; CONT-MAR) or April (group 4: three males; 20 females; CONT-APR). Once the male-to-female contact was established, both odor (ODT) and behavior (BEHT) tests (2 d × 2 h) were performed during both anestrous periods. On day 10 after introduction of the males, in both anestrous periods, one ultrasonography scanning ("US") was performed to quantify the presence, number and size of corpus luteum (US-CL) to determine the effectiveness of the "male effect" and indicators of ovarian activity. Then, on day 45 after introduction of the males, a second US was performed to evaluate pregnancy rate (US-PREG). The EFEM-males, regardless of the phase of the anestrous cycle, had an increased (P < 0.05) odor intensity with respect to the control groups. In addition, while an increased (P < 0.05) ASB occurred in the EFEM-males, no CSB differences (P > 0.05) arose when treatments were compared, neither in March-April nor in April-May. The EFEM-males exposed to acyclic goats in March-April (i.e. early anestrous period), promoted not only the largest estrus and ovulatory responses (P < 0.05), but also the largest pregnancy rate (P < 0.05) in these previously anestrus goats, suggesting that in April-May (i.e. profound anestrous), the presence of active males was not enough to completely suppress cyclic reproductive arrest. This study generates interesting out-of-season reproductive outcomes in a goat population with a large proportion of highly seasonal dairy breeds (i.e. Alpine, Saanen and Toggenburg), augmenting the possibility to expand milk production and the economic income of goat producers across the year. Besides, this practice may serve as an interesting reproductive tool to increase the sustainability of marginal goat production systems under semiarid conditions.

Reproductive outcomes of anestrous goats supplemented with spineless Opuntia megacantha Salm-Dyck protein-enriched cladodes and exposed to the male effect

The possible influence of the "male effect" upon reproductive outcomes of adult anestrous goats under marginal rangeland conditions and supplemented with protein-enriched Opuntia megacantha Salm-Dyck was evaluated. Reproductive variables included: estrus percentage (EST, %), estrus latency (ESL, hours), ovulation percentage (OP, %), ovulation rate (OR, units), average largest follicle at ovulation (LFO, mm), largest corpus luteum (LCL, mm), embryo number (EBN, units), and embryo implantation percentage (EIP, %). During early May, anestrous mix-breed adult goats (Criollo x Alpine-Saanen-Nubian; n = 38, 26° N) were randomly distributed to (1) Control (CC; n = 12), (2), Non-enriched Opuntia (NEO; n = 14), and (3) Protein-enriched Opuntia (PEO; n = 12). Neither LW (P > 0.05) nor BCS (P > 0.05) or any of the evaluated ovarian variables differed (P > 0.05) among treatments; EST = 89.66%, ESL = 53.66 h, OP = 70.33%, OR = 1.07 units, LFO = 4.5 mm, LCL = 9.6 mm, EBN = 0.94 embryos, and EIP = 48.66%. Irrespective of nutritional supplementation regime, all goats denoted an increased response to the male effect just in the middle of the anestrous season and managed under marginal grazing conditions during the dry season (May to June; 26° N). The use of the male effect successfully invoked neurophysiological pathways to re-activate ovarian follicular and luteal pathways during the natural anestrous season in the female goat. Yet, such successful physiological scenario was not equally exerted to promote an increased embryo implantation rate; this issue claims further consideration. Therefore, it is essential to align not only the peri-conceptional but also the peri-implantation stages to the best suited environmental conditions in the rangeland, in order to increase both reproductive and economic efficiency while promoting sustainability in those rangeland-based marginal goat production systems.

Body condition and stage of seasonal anestrus interact to determine the ovulatory response after male biostimulation in anovulatory Criollo × Nubian goats

The effect of goat nutritional condition on the response to biostimulation with sexually active males during different stages of anestrus was determined. Fifty-eight Criollo × Nubian females on high and low body mass index (BMI) diets were used. Each BMI group was divided into two for biostimulation with sexually active males during May (mid-anestrus) or July (transition period). Ovulatory responses to biostimulation were characterized from serum progesterone, as well as the delay for response (first and second ovulations followed by a normal length luteal phase, O-WNLP). The percentage of goats showing one O-WNLP was greater in the high BMI group than in the low BMI group and greater during the transition period than in the mid-anestrus. However, the interaction between factors revealed that the difference between BMI groups was only significant in the transition period and the difference between stages was only significant in goats with high BMI. Occurrence of a second O-WNLP tended to be greater in the high BMI group than in the low BMI group. Response delay was shorter in the transition period than in mid-anestrus. In conclusion, female nutritional status interacting with the stage of anestrus determined the ovulatory response to male biostimulation in crossbred Criollo goats.

Effect of nutritional supplementation upon pregnancy rates of goats under semiarid rangelands and exposed to the male effect

The aim of this study was to evaluate possible effects of improved protein and energy diet upon reproductive outcomes of adult goats under marginal rangeland grazing conditions and exposed to the male effect during the anoestrous-dry season. Adult goats (Nubian × Criollo, nonpregnant, nonlactating, n = 160, 22° 50' N, 100° 59' W, 1,653 m) were randomly divided in two experimental groups: Control (CG; n = 80) and Supplemented (SG; n = 80). Both CG and SG goats were kept together during the day for ranging a semiarid rangeland while separated accordingly at night. SG goats were individually supplemented [400 g kg(-1) day(-1); 14% CP and 2.92 Mcal DE kg(-1)] during a 30-day period. Thereafter, both the CG [35.5 ± 0.94 kg LW, 1.95 ± 0.06 U, body condition score (BCS)] and the SG [39.5 ± 0.94 kg LW, 2.29 ± 0.06 BCS] were exposed to adult males (Nubian, n = 4, two per group) of proven libido and fertility and kept together at night (1700-0900) during a 42-day experimental breeding period. At the beginning of the breeding period, both LW (P < 0.001) and BCS (P < 0.001) were higher in the SG, which was also reflected in higher pregnancy rate (92.5 vs. 76.3%, P < 0.01). Nonetheless, both CG and SG depicted an increased abortion rate (52.5 vs. 41.9% P > 0.05), respectively. Results suggest that nutritional supplementation and the male effect were able to successfully invoke neurophysiological pathways to increase ovarian activity and to promote a uterine milieu prone to the establishment of pregnancy during the anoestrus season. However, the increased abortion rates observed in the study occurred irrespective of the nutritional regime offered during the premating stage. Therefore, there is a need to align the last third of gestation to the onset of the grazing season in order to increase reproductive and economic efficiency in those rangeland-based marginal goat production systems.

The use of melatonin and progestagen-eCG to initiate reproductive activity in prepuberal Awassi ewe lambs

This experiment was conducted to evaluate the effect of administering hormonal treatments (melatonin and progestagen/equine chronic gonadotropin (eCG)) on advancing puberty in Awassi ewe lambs. Fifty-one 6-month-old ewe lambs of similar body weights (around 28 kg) were randomly assigned into four treatment groups; control (CON; n = 14), melatonin (MEL; n = 13), melatonin plus progestagen-eCG (MELPP; n = 11), and progestagen-eCG (PP; n = 13). Ewe lambs in the PP and MELPP groups were fitted with intravaginal progestagen sponges containing 60 mg medroxyprogesterone acetate for 14 days; 400 IU eCG were administered to each of these ewe lambs on the day of sponge removal. Ewe lambs in the MEL and MELPP groups received subcutaneous melatonin implants (Regulin®, 18 mg melatonin) 36 days before sponge insertion. Hormonal treatment had no effect on ewe lamb body weight change. Estrous behavior was greater (p < 0.001) in the PP and MELPP groups than in the CON and MEL ewe lambs. The duration from ram introduction to onset of estrus was shorter (p < 0.05) in the CON, PP, and MELPP than in the MEL ewe lambs. The number of ewe lambs showing luteal activity was greater (p < 0.001) in the MELPP and PP than in the CON and MEL groups. Lambing rate from mating during the first cycle following ram introduction differed significantly (p < 0.01) among treatments being greater in the MELPP and PP than in the CON and MEL groups. Based on these results, it can be concluded that progestagen-eCG appears to be more effective than melatonin in inducing reproductive activity. However, the majority of ewe lambs in the current study either failed to cycle or stopped cycling following the induced estrus. Such failure in advancing puberty may be related to body weight of ewe lambs at the time of mating.