Effect of reproductive indices and bovine somatotropin on milk yield in Holstein cows experiencing climatic sub-fertility

IF 1.1 4区农林科学 Q3 AGRICULTURE, DAIRY & ANIMAL SCIENCE

Mljekarstvo Pub Date : 2023-06-19 DOI:10.15567/mljekarstvo.2023.0302

Marcos Luna

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Abstract

This study aimed at determining the association between reproductive indexes and the total milk yield in non-planed lactations ≥600 days in sub-fertile Holstein cows treated or not with recombinant bovine somatotropin (rbST) and experienced prolonged hyperthermia. A total of 1141 cows with a single lactation were enrolled in the study: 622 were not treated with rbST (control) and 519 were treated with rbST (500 mg every 14 days throughout lactation). Across parities, control cows with >480 days open, produced 5642 kg more milk (p<0.01) than cows with <380 days open. rbST-treated cows produced 5994 more (p<0.01) kg of milk during the entire lactation than cows with <380 days open. In control cows receiving ≥10 services, the average total milk yield was 1811 kg higher (p<0.01) than in cows receiving ≤10 services. In rbST-treated cows, the average total milk yield was 1680 kg higher (p<0.01) in cows receiving ≥10 services, compared to cows receiving ≤10 services. The overall conception rate for all services was 51% and 73% (p<0.01) for control and rbST-treated cows, respectively. In conclusion, the greater the delay to get pregnant and the greater the number of services per lactation the higher the total milk yield per lactation were observed. Thus, in this unusual situation where sub-fertile cows are retained with >380 days open and they continue to be inseminated after 10 unsuccessful services, the impact of delayed conception is not entirely negative as this disadvantage is more than outweighed by the extra milk that is produced when lactation is extended.

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生殖指数和牛生长激素对气候亚育荷斯坦奶牛产奶量的影响

本研究旨在确定在低生育能力的荷斯坦奶牛中，使用或不使用重组牛生长激素(rbST)并经历长时间热疗后，其生殖指标与非计划泌乳总产奶量≥600天的关系。试验共选取1141头单次泌乳奶牛，其中622头奶牛未饲喂rbST(对照组)，519头奶牛饲喂rbST(泌乳期每14天饲喂500 mg)。在所有胎次中，产奶480天的对照奶牛多产了5642公斤的牛奶(产奶380天)，在10次不成功的授精后，它们继续受精卵。延迟受孕的影响并不完全是负面的，因为当哺乳期延长时产生的额外牛奶超过了这种不利影响。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Mljekarstvo Agricultural and Biological Sciences-Animal Science and Zoology

CiteScore

1.90

自引率

41.70%

发文量

审稿时长

12 weeks

期刊介绍： Mljekarstvo is an open access, peer-reviewed international quarterly scientific journal. The first issue was published in 1951, by the Croatian Dairy Operators'' Association (today: Croatian Dairy Union, publisher). In a paper at a Union conference held 28 October 1951 in Zagreb it was said: "Our desire is that this magazine does not meet the fate of its predecessors, but that it continues to reflect the creative efforts and to provide guidelines for the producers as well as all other operators employed in the dairy industry." It is our pleasure today to say that wishes of the enthusiasts who attended the conference have come true, and the magazine Mljekarstvo during the last six decades was a reflection of the creative efforts of numerous dairy scientists and experts, and through its texts it served as a guideline in improving production and processing of milk and dairy products. Mljekarstvo has been following all the achievements of the dairy profession in Croatia, and it also gives the short surveys of world achievements. The result of the research of local and foreign scientists and experts always find their place in the magazine Mljekarstvo. It has been edited by our outstanding dairy experts employed at colleges, research institutions and dairy companies.