Use of Propylene-Glycol as a Cosolvent for GnRH in Synchronization of Estrus and Ovulation in Sheep

The foreseen shortage of eCG for estrus synchronization in sheep makes necessary the development of alternative protocols. The aim of the present work was to evaluate the reproductive response of sheep in breeding season to the administration of GnRH using propylene-glycol as a cosolvent and the subcutaneous route for slowing and extending the release of GnRH, as well as the most adequate timing for such administration. In the present study, protocols based on a short-term CIDR treatment and a single subcutaneous dose of GnRH in propylene-glycol at 36 h after CIDR removal induced a similar ovarian response to protocols based on administration of eCG at CIDR removal or intramuscular GnRH in distilled water at 56 h after. In such protocol, 80% of the animals developed estrus in a narrow timing (75% between 36 and 48 h after CIDR removal), and all of them also ovulated in a narrow window (87.5% between 72 and 76 h after CIDR removal, with 62.5% between 72 and 76 h) and showed a similar ovulation rate and plasma progesterone concentrations at the induced estrous cycle. Hence, administration of GnRH in propylene-glycol may constitute an alternative to traditional protocols based on the administration of eCG

The impact of extensive grazing in the behavior of soluble sugars in Prosopis laevigata (Humb. & Bonpl. ex Willd.) M.C.Johnst. trees

Objective: To evaluate the impact of extensive grazing in the accumulation of soluble sugars in Prosopis laevigata trees, whose leaves and fruits are directly consumed by cattle. Design/Methodology/Approach: The ejido Emiliano Zapata in Durango was the study area. Stem and root samples were collected from a stand of extensive grazing and a stand without cattle. The sampling was carried out in three growth stages: March (flowering), June (fruition), and October (leaf fall). The samples were frozen in liquid nitrogen and were lyophilized. Afterwards, they were ground and 10 mg of dry matter were weighted in microtubes. The total soluble sugars (TSS) concentration was determined following the Van Handel methodology, using a spectrophotometer at 625 nm. The statistical analysis was carried out using an ANOVA and the Tukey’s test. Results: In March, the grazing area had lower TSS concentrations during regrowth than the area without grazing, both at root and stem levels. Study Limitations/Implications: The intensity of grazing and the pasture rotation should be regulated to favor carbohydrate accumulation in trees, which is required for the formation of the meristematic tissues. Finding/Conclusions: Extensive grazing has an impact on the synthesis and accumulation of TSS in mesquite trees. Therefore, the consumption of branches, leaves, and fruits decreases TSS concentrations in the stem and the root

Targeted glutamate supply boosts insulin concentrations, ovarian activity, and ovulation rate in yearling goats during the anestrous season

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

Reproductive efficiency of Ovsynch + CIDR in Holstein cows under a fixed time artificial insemination scheme in northern Mexico

Se evaluó el uso de Ovsynch más dispositivo intravaginal de liberación controlada de progesterona (CIDR) en vacas altas productoras. El estudio se llevó en la Comarca Lagunera (25° 44´ N, 103° 10´ O a 1,111 msnm) durante diciembre y enero. Las vacas (n=100) se pre-sincronizaron con dos inyecciones de PGF2α a los 35 y 47 días posparto y asignadas a dos tratamientos (n= 50): 1) El grupo OV recibió el protocolo Ovsynch: 100 μg de GnRH (i.m.; día 1), 25 mg de PGF2α (i.m.; día 7) y 100 μg GnRH (i.m.; día 9); 2) El grupo (OV+C) recibió el protocolo Ovsynch más un CIDR (1.38 g), retirado siete días después. Todas las vacas se expusieron a un protocolo de inseminación artificial a tiempo fijo (IATF; 16 a 20 h posteriores a la última inyección). Se registró tanto el porcentaje de preñez, el número de vacas repitiendo celo considerando dos periodos (≤24 y ≥25 días post-inseminación), así como los días de retorno al celo. Mientras que no existió diferencia entre grupos para tasa de preñez (OV= 28 %, OV+C= 32 %; P>0.05), el porcentaje de vacas que manifestaron celo después de la IATF difirió (P0.05), the percentage of cows showing estrus after IATF differed (P<0.05) between treatments for the two studied periods (28 % vs 62 % ≤24 d; 69 % vs 35 % ≥25 d; OV and OV+C, respectively). Moreover, mean of days when cows repeated estrus was lower (P<0.05) in the OV+C group (25 ± 1.6 vs 30 ± 1.3 d). Although the Ovsynch+CIDR treatment did not improve pregnancy rate, it reduced the latency for return to estrus, emerging as an alternative to diminish the days to the next AI, and potentially improve the reproductive efficiency and the economic return of the dairy herd

Glutamate Supply Reactivates Ovarian Function while Increases Serum Insulin and Triiodothyronine Concentrations in Criollo x Saanen-Alpine Yearlings’ Goats during the Anestrous Season

The possible effect of glutamate supplementation upon ovarian reactivation and serum concentrations of insulin (INS) and triiodothyronine (T3) in anestrous yearling goats was evaluated. Goats (n = 32, 12 mo., 26&deg; North, 1117 m) with a similar live weight (LW) and body condition score (BCS) were blood sampled twice per week for two weeks (2 &times; 1 week &times; 2 weeks) to confirm the anestrus status (&lt;1 ng P4/mL; RIA). Thereafter, goats were randomly assigned to either 1) Glutamate (GLUT; n = 16, LW = 27.1 &plusmn; 1.09 kg, 3.5 &plusmn; 0.18 units, IV-supplemented with 7 mg of glutamate kg&minus;1 LW), or 2) Control (CONT; n = 16; LW = 29.2 &plusmn; 1.09 kg; BCS = 3.5 &plusmn; 0.18, IV saline). During the treatment period, 16 goats (eight/group) were blood sampled twice per week for six weeks. Such serum samples (2 &times; 1 week &times; 6 weeks) were quantified by their P4 content to evaluate the ovarian-luteal activity, whereas a sample subset (1 &times; 1 week &times; 6 weeks) was used to quantify their INS &amp; T3 content to evaluate their metabolic status. Neither LW (28.19 kg; p &gt; 0.05) nor BCS (3.51 units; p &gt; 0.05) differed between treatments. Goats depicting ovarian reactivation favored the GLUT group (50 vs. 12.5%; p &lt; 0.05). Neither INS (1.72 &plusmn; 0.15 ng mL&minus;1) nor T3 (2.32 &plusmn; 0.11 ng mL&minus;1) differed between treatments, yet a treatment x time interaction regarding INS &amp; T3 concentration across time favored (p &lt; 0.05) the GLUT group. The results unveil exogenous glutamate as an interesting modulator not only of ovarian reactivation, but of metabolic hormone synthesis