Institut de Ciència i Tecnologia Animal, Universitat Politècnica de València, Cami de Vera, s/n, Valencia, Spain.
J Dairy Sci. 2013 Jul;96(7):4368-74. doi: 10.3168/jds.2012-6393. Epub 2013 May 9.
Two repeated experiments were carried out in 2 different years to study the effect of estrus on somatic cell count (SCC) in dairy goats. In the first year, 36 Murciano-Granadina goats were used [12 primiparous and 24 multiparous; 22 healthy and 14 with an intramammary infection (IMI)] and, after a 6-d pre-experimental period, were divided into 2 groups according to lactation number, udder health status, SCC, and milk production. One group was kept as a control, whereas the other received an estrus synchronization hormonal treatment lasting 11d. At 24, 48, and 72h after cessation of the hormone treatment, goats were placed in contact with a buck to confirm that they were in estrus. For 32 consecutive days (6 pre-experimental, 11 in hormone treatment, and 15 post-treatment) the SCC per gland and udder were monitored in all animals. In the second year, we repeated the same experimental design using a total of 38 Murciano-Granadina breed goats (12 primiparous and 26 multiparous; 26 healthy and 12 with IMI). Throughout this experiment, milk yield and composition were also recorded daily for each goat. Upon termination of the hormonal treatment, the SCC in udder milk increased significantly in the treatment group compared with the control group over 3 consecutive days. This increase was observed for year (1 and 2), parity (primiparous and multiparous), and udder health status (healthy and IMI). The log10 SCC (cells/mL) increased from 5.5±0.09 before estrus to 6.04±0.09 during treatment; therefore, the geometric mean of the SCC increased 3.5 times during treatment. The maximum values obtained in healthy glands of primiparous goats (geometric mean=0.37 million cells/mL) were lower than in healthy glands (1.1 million cells/mL) or infected glands (1.7 million cells/mL) of multiparous goats. The increase in SCC observed during estrus (200% increase in geometric means) could not be explained by the changes in milk production, which only fell by 13%. During estrus, the percentage of protein and dry matter in the milk also increased significantly. We concluded that it is necessary to consider the presence of estrus to correctly interpret milk SCC, as an indirect method for detecting IMI or as a commercial milk quality parameter.
这项研究在两年中的两个不同年份进行了两次重复实验，以研究发情对乳用山羊体细胞计数（SCC）的影响。在第一年，使用了 36 只穆尔西亚-格拉纳迪纳山羊[12 只初产和 24 只经产；22 只健康和 14 只患有乳腺炎（IMI）]，经过 6 天的预实验期后，根据泌乳数、乳房健康状况、SCC 和产奶量将它们分为两组。一组为对照组，另一组接受为期 11 天的发情同步激素处理。在激素处理停止后 24、48 和 72 小时，将山羊与公山羊接触以确认它们处于发情状态。在连续 32 天（6 天预实验、11 天激素处理和 15 天处理后）中，对所有动物的每个腺体和乳房的 SCC 进行监测。在第二年，我们使用总共 38 只穆尔西亚-格拉纳迪纳品种的山羊重复了相同的实验设计[12 只初产和 26 只经产；26 只健康和 12 只患有 IMI]。在整个实验过程中，还每天记录每只山羊的产奶量和成分。在激素处理结束时，与对照组相比，处理组在连续 3 天内乳房牛奶中的 SCC 显著增加。这种增加在年度（1 年和 2 年）、胎次（初产和经产）和乳房健康状况（健康和 IMI）中均观察到。log10 SCC（细胞/mL）从发情前的 5.5±0.09 增加到处理期间的 6.04±0.09；因此，处理期间 SCC 的几何平均值增加了 3.5 倍。初产健康腺体中获得的最高 SCC 值（几何平均值=0.37 百万细胞/mL）低于经产健康腺体（110 万细胞/mL）或感染腺体（170 万细胞/mL）。发情期间 SCC 的增加（几何平均值增加 200%）不能用产奶量的变化来解释，产奶量仅下降了 13%。在发情期间，牛奶中的蛋白质和干物质百分比也显著增加。我们得出的结论是，有必要考虑发情的存在，以正确解释牛奶 SCC，将其作为检测乳腺炎的间接方法或作为商业牛奶质量参数。
