Pereira M H C, Cappellozza B I, Kloster A K M, Mamedes M, Vasconcelos J L M
Faculdade de Medicina Veterinária e Zootecnia, Universidade Estadual Paulista (UNESP), Botucatu, SP 18618-000, Brazil.
Chr. Hansen A/S, Hørsholm 2970, Denmark.
Anim Reprod Sci. 2023 Oct;257:107324. doi: 10.1016/j.anireprosci.2023.107324. Epub 2023 Aug 30.
Three experiments were designed to evaluate the effects of conventional and sexed-semen on reproductive performance of dairy females detected in estrus. In Exp. 1, 978 lactating Holstein cows and 116 Holstein heifers were used. Cows or heifers were randomly assigned to receive conventional (CONV) or sexed (SEXD) semen on day 0 of a TAI protocol. The TAI was performed using commercial CONV or SEXD frozen-thawed semen from the same 6 Holstein bulls, and SEXD semen was sexed through fluorescence cytometry. In Exp. 2, 390 lactating Holstein × Gir dairy cows and 344 Holstein × Gir heifers were used. Cows and heifers were randomly assigned to receive CONV or SEXD semen on day 0 with frozen-thawed semen from 5 Holstein × Gir bulls. The SEXD was sorted through the Sexcel™ methodology. In Exp. 3, 789 primiparous lactating Holstein cows were enrolled. Cows were randomly assigned to receive CONV or SEXD semen from 5 Holstein bulls, and the SEXD semen was sexed using the same semen allocation methodology described in Exp. 2. All data were analyzed using SAS. Regardless of the experiment, no treatment × bull interaction was observed for any of the variables analyzed herein (P ≥ 0.20). In Exp. 1, multiparous cows assigned to CONV had a greater P/AI vs. cohorts assigned to SEXD (P < 0.01) and a similar response tended to be observed for secundiparous cows (P = 0.10). No treatment effects were further observed when the effects of semen on day 60 P/AI were stratified by heat stress, milk yield, and CL at the beginning of the protocol. In Exp. 2, no P/AI differences between treatment were detected either on days 32 (P = 0.32) or 60 of pregnancy (P = 0.20). In Exp. 3, cows assigned to SEXD had reduced P/AI on day 32 (P = 0.03) and tended to have a reduced P/AI on day 60 of pregnancy (P = 0.06). No further treatment effects or interactions were observed herein (P ≥ 0.13). Overall P/AI of SEXD semen was 78% of the CONV (P < 0.01), but the variation of these results requires some attention. Moreover, an additional analysis was performed considering the median value of P/AI in bulls assigned to CONV and SEXD, and bulls that had a greater P/AI in CONV also had a greater P/AI in SEXD (P = 0.03). In summary, although not directly comparable, the sexing technologies herein provided similar results in heifers, but not in other categories (primiparous, secundiparous, and multiparous cows). Additionally, the P/AI of a sexed semen is associated to its performance on the conventional semen counterpart. Moreover, in the present experiment, no other parameters were shown to impact fertility of dairy females assigned to conventional or sexed-semen.
设计了三项试验来评估常规精液和性别分选精液对处于发情期的泌乳奶牛繁殖性能的影响。在试验1中，使用了978头泌乳荷斯坦奶牛和116头荷斯坦小母牛。奶牛或小母牛在定时人工授精（TAI）方案的第0天被随机分配接受常规（CONV）或性别分选（SEXD）精液。TAI使用来自相同6头荷斯坦公牛的商业CONV或SEXD冻融精液进行，SEXD精液通过荧光细胞术进行性别分选。在试验2中，使用了390头泌乳荷斯坦×吉尔奶牛和344头荷斯坦×吉尔小母牛。奶牛和小母牛在第0天被随机分配接受来自5头荷斯坦×吉尔公牛的CONV或SEXD冻融精液。SEXD通过Sexcel™方法进行分选。在试验3中，纳入了789头初产泌乳荷斯坦奶牛。奶牛被随机分配接受来自5头荷斯坦公牛的CONV或SEXD精液，SEXD精液使用试验2中描述的相同精液分配方法进行性别分选。所有数据使用SAS进行分析。无论试验如何，在此分析的任何变量均未观察到处理×公牛的交互作用（P≥0.20）。在试验1中，分配到CONV的经产奶牛的受孕率/人工授精次数（P/AI）高于分配到SEXD的牛群（P<0.01），经产二胎奶牛也观察到类似趋势（P=0.10）。当根据热应激、产奶量和方案开始时的黄体（CL）对第60天P/AI时精液的影响进行分层时，未进一步观察到处理效应。在试验2中，在妊娠第32天（P=0.32）或第60天（P=0.20）均未检测到处理间的P/AI差异。在试验3中，分配到SEXD的奶牛在第32天的P/AI降低（P=0.03），在妊娠第60天P/AI有降低趋势（P=0.06）。在此未观察到进一步的处理效应或交互作用（P≥0.13）。SEXD精液的总体P/AI为CONV的78%（P<0.01），但这些结果的变异性需要一些关注。此外，考虑分配到CONV和SEXD的公牛中P/AI的中位数进行了额外分析，在CONV中P/AI较高的公牛在SEXD中P/AI也较高（P=0.03）。总之，尽管不可直接比较，但本文中的性别分选技术在小母牛中提供了相似的结果，但在其他类别（初产、经产二胎和经产奶牛）中并非如此。此外，性别分选精液的P/AI与其在常规精液对应物上的性能相关。而且，在本试验中，未显示其他参数会影响分配到常规或性别分选精液的泌乳奶牛的繁殖力。
