-The objective of this work was to evaluate the influence of low-stress handling (LSH) on reactivity score and pregnancy rate during fixed-time artificial insemination (FTAI) for extensively raised Nellore cows. Multiparous cows (n = 126) were randomly allocated into two groups: G1 (n = 66) and G2, the control group (n = 60). Group G1 was subjected to LSH, in which the animals were handled in a calm and quiet manner, without loud noises or physical aggression, using the point of balance, respecting the flight zone and using flags to supplement handling. Group G2 was handled following the typical procedure, with yelling, kicking and the use of electric prods and sticks. On D0, D8 and D10, FTAI was performed in both groups. Reactivity was scored on D0, D8 and D10 at the squeeze chute, based on the tension score, breathing score, and bellowing score. Using the three criteria above, the reactivity scores were defined as follows: R1 (calm); R2 (slightly reactive); R3 (moderately reactive); R4 (reactive); and R5 (highly reactive). Thirty-five days after artificial insemination, pregnancy was determined using ultrasonography. There was no significant correlation between reactivity score and pregnancy rate in each group or between the pregnancy rates in both groups. However, there was a statistically significant difference between the G1 and G2 groups with regard to reactivity score (1.62±0.05 vs. 2.12±0.07). Low-stress handling influenced reactivity but did not affect pregnancy rate in extensively raised Nellore cows subjected to FTAI.
The aim of this study was to establish a comparison between heterospermic and monospermic semen on the pregnancy rate of fixed-time AI Bos indicus cows. The experiment was conducted in the state of Mato Grosso, Brazil, during December 2010 and February 2011. Multiparous (n = 173) and primiparous (n = 204) Nelore cows, 45 ± 15 days postpartum, were evaluated on body condition score (BCS; score 1 to 9), and those that presented BCS between 5 and 8 were selected. Two protocols of estrous cycle synchronization were performed (PeCG and Pshang). Synchronization of the estrous cycle was achieved with the aid of the following protocol: on Day 0, all animals were treated with a progesterone vaginal implant with 1.9 g of progesterone combined with an IM injection of 2 mg of estradiol benzoate. On Day 7, an IM injection of 12.5 mg of dinoprost was administered. On Day 9, implants were withdrawn and the animals received an IM injection of 0.5 mg of estradiol cypionate. On Day 9, part of the animals (n = 222) received an IM injection of 300 IU mg of eCG (PeCG) and the other part (n = 155) had their calves removed for 48 hours (Pshang). All animals were inseminated 46 to 52 h after the end of the protocol. Cows were allocated randomly in 4 groups according to the donor male sample in the semen straw and groups were designated as MA (monospermic straw from bull A; n = 110), MB (monospermic straw from bull B; n = 102), MC (monospermic straw from bull C; n = 108), and HT (heterospermic sample from bulls A, B, and C; n = 57). Commercially available semen straws from Aberdeen Angus donors were used (ABS Pecplan, Brazil). Pregnancy diagnosis was performed 35 days after AI using real-time ultrasonography. Results are summarized in Table 1. There was no statistical difference between MA, MB, MC, and HT in any group according to the chi-square test (P > 0.05). However, there was a remarkable difference in pregnancy rates among the 3 bulls tested considering both protocols, probably due to the variation in the ovulation moment. Table 1.Pregnancy rates of Nelore cows submitted to FTAI protocol inseminated with monospermic (bull A, B, or C) or heterospermic (HT) semen
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.