Colostrum management is crucial for enhancing the immune response against enteropathogens and the survival of dairy calves during the first few weeks of life. However, few physiological studies have investigated the dynamics of general and specific immunoglobulin G (IgG) content in cow milk during early lactation stages, particularly in that of crossbred Gir × Holstein dairy cows, the most predominant dairy cattle population in tropical countries, such as Brazil. Therefore, this study evaluated the effects of parity and milking order on the volume and quality of colostrum, transition milk, and mature milk in crossbred Gir × Holstein cows using three traditional on-farm tests. The dynamics of IgG in the mammary secretions and the specific antibody levels against enteropathogens were also determined using sandwich enzyme-linked immunosorbent assay (ELISA) during the early stages of lactation. Fifty healthy Gir × Holstein cows were divided into two groups based on parity number, i.e., primiparous (n = 18) and multiparous (n = 33). They were monitored from the first to the 43rd milking. The colostrum volume and quality were evaluated using a colostrometer, Brix refractometer, and Colostro Balls after the first milking, in addition to the colostral IgG levels measured using sandwich ELISA as a reference standard. On-farm tests showed that the colostrum samples obtained from Gir × Holstein cows exhibited an optimal colostrum quality based on the literature criteria, regardless of parity number; however, the IgG mass was higher in the colostrum of multiparous (201 ± 67.03 g) cows than in that of primiparous (144 ± 32.40 g) cows. The volume and composition of transition and whole milk were also assessed at the second to ninth, 11th, 13th, 15th, 29th, and 43rd milkings. Multiparous cows produced higher volumes of transition milk than primiparous cows. In addition, multiparous cows exhibited a higher total solids percentage in their postpartum mammary secretions than primiparous cows. A higher percentage of inhibition of specific antibodies against Escherichia coli K99 was observed in the blood serum of multiparous cows than in that of primiparous cows. The volume and composition of mammary secretions changed over time; milk production increased, whereas total solids, total IgG, and specific antibody levels against most enteropathogens decreased, regardless of parity. Additionally, an association between parity and time was observed with respect to milk yield, the Brix score (%), and specific antibody levels against the Clostridium perfringens alpha toxin in mammary sections and against coronavirus and rotavirus in blood samples. This association indicated higher values in multiparous cattle than in primiparous cattle at specific time points. In conclusion, this study reveals postpartum time-dependent changes in the physiological and immunological components in the mammary secretions and blood of crossbred Gir × Holstein cows from the first to the 43rd milking. These results will contribute to the development of future research in Gir × Holstein-specific neonatology, which is genetically adapted to tropical and subtropical countries.

中文翻译：

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杂交 Gir ×荷斯坦奶牛初乳和过渡乳中初乳的免疫质量和抗肠道病原体的特异性抗体


初乳管理对于增强对肠道病原体的免疫反应和奶牛在出生后最初几周的存活至关重要。然而，很少有生理学研究调查泌乳早期牛奶中一般和特异性免疫球蛋白 G （IgG） 含量的动态变化，特别是在杂交 Gir ×荷斯坦奶牛中，这是热带国家最主要的奶牛种群，如巴西。因此，本研究使用三种传统的农场测试评估了胎次和挤奶顺序对杂交 Gir ×荷斯坦奶牛初乳、过渡奶和成熟奶量和质量的影响。在哺乳早期，还使用夹心酶联免疫吸附测定 （ELISA） 测定乳腺分泌物中 IgG 的动力学和针对肠道病原体的特异性抗体水平。根据胎次数将 50 头健康的 Gir × 荷斯坦奶牛分为两组，即初产奶牛 （n = 18） 和经产奶牛 （n = 33）。从第一次挤奶到第 43 次挤奶，他们都受到监控。第一次挤奶后，使用结肠计、白利糖度折光仪和牛初乳球评估初乳体积和质量，此外，使用夹心 ELISA 作为参考标准测量初乳 IgG 水平。农场测试表明，根据文献标准，从 Gir × Holstein 奶牛获得的初乳样品表现出最佳的初乳质量，无论胎次数如何;然而，经产奶牛 （201 ± 67.03 g） 初乳的 IgG 质量高于初产奶牛 （144 ± 32.40 g） 的初乳。还评估了第 2 至 9 次、第 11 次、第 13 次、第 15 次、第 29 次和第 43 次挤奶的过渡奶和全脂奶的体积和成分。 经产奶牛比初产奶牛产生更多的过渡奶。此外，经产奶牛产后乳腺分泌物中的总固形物百分比高于初产奶牛。在经产奶牛的血清中观察到针对大肠埃希菌 K99 的特异性抗体的抑制百分比高于初产奶牛。乳腺分泌物的体积和成分随时间而变化;牛奶产量增加，而总固形物、总 IgG 和针对大多数肠道病原体的特异性抗体水平下降，无论胎次如何。此外，在产奶量、白利糖度评分 （%） 和针对乳腺切片中产气荚膜梭菌 α 毒素以及血液样本中冠状病毒和轮状病毒的特异性抗体水平方面观察到胎次与时间之间的关联。这种关联表明，在特定时间点，经产牛的值高于初产牛。总之，本研究揭示了杂交 Gir ×荷斯坦奶牛从第一次挤奶到第 43 次挤奶的乳腺分泌物和血液中生理和免疫成分的产后时间依赖性变化。这些结果将有助于 Gir × 荷斯坦特异性新生儿学的未来研究发展，该新生儿学在基因上适应热带和亚热带国家。