Department of Veterinary Medicine and Animal Reproduction, Faculdade de Ciências Agrárias e Veterinárias, UNESP, University Estadual Paulista, Jaboticabal, SP, Brazil.
Theriogenology. 2012 Nov;78(8):1800-13. doi: 10.1016/j.theriogenology.2012.07.007. Epub 2012 Sep 9.
The objective was to determine the effect of sequence of insemination after simultaneous thawing of multiple 0.5 mL semen straws on conception rate in suckled multiparous Nelore cows. The effect of this thawing procedure on in vitro sperm characteristics was also evaluated. All cows (N = 944) received the same timed AI protocol. Ten straws (0.5 mL) of frozen semen from the same batch were simultaneously thawed at 36 °C, for a minimum of 30 sec. One straw per cow was used for timed AI. Frozen semen from three Angus bulls was used. Timed AI records included sequence of insemination (first to tenth) and time of semen removal from thawing bath. For laboratory analyses, the same semen batches used in the field experiment were evaluated. Ten frozen straws from the same batch were thawed simultaneously in a thawing unit identical to that used in the field experiment. The following sperm characteristics were analyzed: sperm motility parameters, sperm thermal resistance, plasma and acrosomal membrane integrity, lipid peroxidation, chromatin structure, and sperm morphometry. Based on logistic regression, there were no significant effects of breeding group, body condition score, AI technician, and sire on conception rate, but there was an interaction between sire and straw group (P = 0.002). Semen from only one bull had decreased (P < 0.05) field fertility for the group of straws associated with the longest interval from thawing to AI. However, the results of the laboratory experiment were unable to explain the findings of the field experiment. Sperm width:length ratio of morphometric analysis was the single sperm characteristic with a significant interaction between sire and straw group (P = 0.02). It was concluded that sequence of insemination after simultaneous thawing of 10 semen straws can differently affect conception rates at timed AI, depending on the sire used. Nevertheless, the effects of this thawing environment on in vitro sperm characteristics, remain to be further investigated.
本研究旨在确定在同时解冻多支 0.5 毫升细管精液后，输精顺序对哺乳期经产荷斯坦奶牛受胎率的影响。还评估了这种解冻程序对体外精子特性的影响。所有奶牛（N = 944）均接受相同的定时人工授精（AI）方案。将同一批次的 10 支（0.5 毫升）冷冻精液同时在 36°C 下解冻，解冻时间至少 30 秒。每头奶牛使用一支细管进行定时 AI。使用了来自三头安格斯公牛的冷冻精液。定时 AI 记录包括输精顺序（第 1 至第 10 支）和精液从解冻浴中取出的时间。对于实验室分析，使用与田间试验相同的精液批次。从同一批次中取出 10 支冷冻细管，在与田间试验中使用的解冻装置相同的解冻装置中同时解冻。分析了以下精子特性：精子运动参数、精子耐热性、质膜和顶体膜完整性、脂质过氧化、染色质结构和精子形态学。基于逻辑回归，繁殖组、体况评分、AI 技术员和公牛对受胎率没有显著影响，但公牛和细管组之间存在相互作用（P = 0.002）。只有一头公牛的精液在与解冻至 AI 时间间隔最长的细管组相关的组中，田间活力降低（P < 0.05）。然而，实验室试验的结果无法解释田间试验的结果。形态学分析中精子宽度：长度比是与公牛和细管组具有显著相互作用的唯一精子特性（P = 0.02）。因此，在同时解冻 10 支精液细管后，输精顺序可能会根据所用公牛的不同，对定时 AI 的受胎率产生不同的影响。然而，这种解冻环境对体外精子特性的影响仍有待进一步研究。
