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Simple Summary: In the arid lands of Northern Mexico, there are several dairy cattle clusters managed under intensive production systems and fed completely with mixed rations, yet 3–5% feed rejection of the total ration offered has been reported. This surplus feed retains a high nutritional value which could be used to improve the reproductive efficiency of goats managed under marginal–extensive schemes. Therefore, we visualized an interesting research opportunity based on the circular economy approach. We hypothesized that a short-term supplementation with feed leftovers from dairy farms (i.e., intensive system) will increase the reproductive outcomes of rangeland managed goats (i.e., extensive system), trying to promote the circularity/connectedness between two highly discordant production systems. Our study intended to elucidate this working hypothesis. Based on a circular economy approach, we evaluated the possible effect of targeted supplementation with leftover feed from dairy cows (i.e., intensive system) on the reproductive performance of crossbred/rangeland goats (i.e., extensive system) in arid Northern Mexico. During the deep-anestrous season (i.e., March–April, 25° North), multiparous goats (n = 38) with a similar body weight (BW) and body condition score (BCS) were randomly assigned to two groups: (1) supplemented group (SG; n = 19; BCS: 1.76 ± 0.07; BW: 43.7 ± 1.8 kg), receiving 400 g goat d−1 of dairy-cow-feed leftovers prior to grazing; and (2) non-supplemented group (NS; n = 19; BCS: 1.76 ± 0.06; BW: 44.3 ± 2.5 kg). Both groups were directed to the rangeland for a period of ≈8 h. While the experimental period lasted 36 d, the experimental breeding considered 11 d (d0–d10). The anovulatory status of goats was ultrasonographically confirmed on days −20, −10, and −1 prior to male–female interaction. Previously, bucks were separated for 3 weeks from the experimental females and received exogenous testosterone every third day (i.e., 50 mg i.m.) prior to mating. With respect to the response variables, namely BW, BCS, blood glucose levels (BGLs), estrus induction (GIE, %), latency to estrus (LTE, h), estrus duration (ED, h), and luteal tissue volume (LTV, mm), no differences (p > 0.05) occurred between experimental groups. However, the response variables, namely goats ovulating (GO, %; 78.9 vs. 47.3), total number of corpuses luteum (TNCL, n; 27 vs. 13), ovulation rate (OR, n; 1.42 vs. 0.73), multiple ovulation (MO, %; 73.3 vs. 55.5), and pregnancy rate on d 36 (PRd36, %, 68.4 vs. 36.8), favored (p < 0.05) the SG over the NS goats. Our results demonstrate that connecting the circularity of two divergent ruminant production systems (i.e., cow-intensive and goat-extensive) by using dairy cows' feed leftovers as a targeted supplementation strategy in anestrous goats under a marginal-rangeland production system enhanced out-of-season reproductive outcomes (i.e., ovulation rate and pregnancy rate), thus benefiting marginal goat producers and their families. [ABSTRACT FROM AUTHOR]

The possible effect of body condition score (BCS) on ovarian function, sexual behavior, (i.e., females and males; appetitive and consummative), estrus, ovulation, and reproductive performance was investigated in crossbred dairy goats under extensive conditions. Based on their BCS, female goats (n = 48) were divided into two experimental groups, either with a low (LG; 1.0 ± 0.2 units; n = 26) or with a high BCS (HG: 2.5 ± 0.9 units; n = 22). Bucks n = 4; cc = 2.5. Female sexual behavior (i.e., acceptance of anogenital sniffing and approach, flight, and tail wagging) was higher in the HG (p < 0.05). In addition, bucks exposed to HG goats showed more approach and mounting attempts (p < 0.01). There were no significant differences (p > 0.05) between the groups in either the follicular diameter or size. Interestingly, although follicular volume, pregnancy rate, kidding rate, and total number of kids born alive were higher in the HG goats (p < 0.05), there were no significant differences (p < 0.05) in fetal mortality and prolificacy between the HG and LG goats. In addition, the response variables of female ovulation, total number of corpus luteum, ovulation rate, corpus luteum diameter, and luteal tissue volume were more favorable in the HG goats (p < 0.05). Our research results demonstrate that a higher BCS improves not only the reproductive responses, but also sexual behavior (i.e., female and male). Larger ovarian structures, higher ovulation rates, higher pregnancy and kidding rates, and higher prolificacy were observed in the HG goats managed under a marginal semiarid extensive production system. [ABSTRACT FROM AUTHOR]

Simple Summary: Our research question considered whether exogenous glutamate administration would enhance serum insulin levels linked to augmented ovarian activity in yearling goats during the anestrous season. The obtained research outcomes support our initial working hypothesis. Certainly, we found that glutamate evokes serum insulin increases across time, enhancing in parallel the out-of-season ovarian activity, which is an augmented ovulation rate in yearling goats. The neuroendocrine regulation of the seasonal reproductive axis requires the integration of internal and external signals to ensure synchronized physiological and behavioral responses. Seasonal reproductive changes contribute to intermittent production, which poses challenges for optimizing goat product yields. Consequently, a significant objective in seasonal reproduction research is to attain continuous reproduction and enhance profitability in goat farming. Glutamate plays a crucial role as a modulator in several reproductive and metabolic processes. Hence, the aim of this study was to evaluate the potential impact of exogenous glutamate administration on serum insulin concentration and ovarian function during the out-of-season period in yearling goats. During the anestrous season, animals were randomly located in individual pens to form two experimental groups: (1) glutamate (n = 10, live weight (LW) = 29.1 ± 1.02 kg, body condition score (BCS) = 3.4 ± 0.2 units) and (2) control (n = 10; LW = 29.2 ± 1.07 kg, BCS = 3.5 ± 0.2), with no differences (p < 0.05) regarding LW and BCS. Then, goats were estrus-synchronized, and blood sampling was carried out for insulin quantification. Ovaries were ultrasonographically scanned to assess ovulation rate (OR), number of antral follicles (AFs), and total ovarian activity (TOA = OR + AF). The research outcomes support our working hypothesis. Certainly, our study confirms that those yearling goats treated with exogenous glutamate displayed the largest (p < 0.05) insulin concentrations across time as well as an augmented (p < 0.05) out-of-season ovarian activity. [ABSTRACT FROM AUTHOR]

The possible relationship between udder morphometric variables (UMVs), chemical quality (CHQ) of both colostrum (CA), and milk (MK), as affected by goat's social rank (SR) (i.e., low-LSR, or high-HSR), was assessed. In late June, goats (Alpine–Saanen–Nubian x Criollo; n = 38; 25° N) were estrus-synchronized and subjected to a fixed-time artificial insemination protocol. Thereafter, in October, while a behavioral study was performed in confirmed-pregnant goats to define the SR classes (n = 15), live weight (LW), body condition (BCS), and serum glucose (GLUC) were registered on the last day of the behavioral study. The expected kidding date was 25 November. Both the UMVs (i.e., seven dates) and the CHQ (i.e., either one for CA and three times for MK) were collected across time (T). The UMVs involved udder perimeter (UDPER, cm), udder diameter (UDDIA, cm), left-teat (LTPER, cm) and right-teat perimeter (RTPER, cm), left-teat (LTLT, cm) and right-teat length (RTLT, cm), left-teat diameter (LTDIA, cm) and right-teat diameter (RTDIA, cm), and medium suspensory ligament (MSL, cm). The registered CHQ variables for both CA and MK were fat (FAT), protein (PRO), lactose (LAC), nonfat solids (NFS), freezing point (FP), and total solids (TS). The possible effect of SR, T, and the SR × T interaction upon the described response variables was tested. While LW favored the HSR goats (54.6 vs. 48.2 ± 1.7 kg; p < 0.05), neither BCS nor GLUC differed (p > 0.05) between SR. An SR × T interaction affected (p < 0.05) most UMVs (i.e., UDPER, MSL, LTLT, RTLT, LTDIA, and RTDI). UMV differences were associated with both changes across time and between SR. Whereas RTLT, LTDIA, RTDIA, and MSL showed their highest values one week prior to kidding, the largest UDPER values (p < 0.05) occurred within the week of kidding. Additionally, HSR goats showed increased values regarding UDPER, MSL, and LTLT. No differences (p < 0.05) between SR occurred regarding the CA-CHQ (i.e., FAT, PRO, LAC, NFS, FP, and TS). Still, an SR x T interaction affected (p < 0.05) the MK content of FAT, PRO, and NFS; while the largest values (p < 0.05) occurred on Day 7 postpartum, the other MK constituents decreased as the lactation advanced. Further, the HSR goats showed an enlarged MK-CHQ (i.e., FAT, PRO, and NFS). HSR goats merged some central behaviors such as aggressiveness, assertiveness, and supremacy to have primacy to feed access, augmenting their LW. Whereas said bodyweight advantage was not reflected upon in CA-CHQ, HSR goats augmented some morphological udder values (i.e., UDPER, MSL, and LTLT) and produced the best MK-CHQ (i.e., > FAT, > PRO, and > NFS) during early lactation. Therefore, both social rank (i.e., HSR goats), as well as the temporal transition stage from the last third of pregnancy to the first phase of lactation (i.e., time), operated as important modulators upon both udder architecture and milk quality in crossbred dairy goats under a dry-semiarid production system. [ABSTRACT FROM AUTHOR]