宁夏地区荷斯坦牛乳成分及相关指标的非遗传因素、体细胞评分变化规律

    Variation characteristics of non-genetic factors and somatic cell score for raw milk composition and related traits of Holstein in Ningxia region

    • 摘要:
      目的  阐明非遗传因素对宁夏地区荷斯坦牛乳成分及相关指标的影响。
      方法  基于宁夏地区荷斯坦奶牛DHI测定数据,利用SAS 9.2软件GLM过程分析胎次、泌乳时期和产犊季节对9项泌乳性状的影响,并探究泌乳性状在不同体细胞评分中的变化规律。
      结果  胎次、泌乳时期、产犊季节、泌乳时期×产犊季节对9项泌乳性状的影响均达到显著水平(P<0.05)。对不同胎次进行比较,乳脂率和乳固形物含量在第2胎后显著下降(P<0.05),乳蛋白率和高峰奶量在第3胎后显著下降(P<0.05);日产奶量第4胎后稍有降低;乳糖率则呈现先下降后上升的趋势,在第3胎达到最低(P<0.05),为4.84%。体细胞评分随着胎次的增加逐渐上升,泌乳高峰日在第1胎次最晚出现(94.07 d),第4胎次最早(67.33 d)。对不同泌乳时期进行比较,日产奶量和乳糖率在第2、3胎随着泌乳时期的延长逐步下降(P<0.05),而乳蛋白率、乳固形物含量、体细胞评分和乳脂率呈上升趋势(P<0.05)。对不同产犊季节进行比较,1~3胎乳脂率和第1胎乳固形物含量春季至冬季均逐步下降;第1胎日产奶量和乳糖率呈上升趋势,到第2、3胎时在夏季分别处于最低水平;1~3胎乳蛋白率、体细胞评分、泌乳高峰日和高峰奶量春季至冬季均呈先升高后降低的趋势,且各性状不同胎次均在夏季达到最高水平。随着体细胞评分增高,乳糖率、日产奶量及高峰奶量整体上逐渐下降,乳脂率和乳蛋白率呈缓慢上升趋势,乳固形物含量和泌乳高峰日在体细胞评分分别为4和5时达到最高水平。
      结论  本研究结果为提高宁夏地区荷斯坦奶牛泌乳性能及生鲜乳质量提供了理论依据。

       

      Abstract:
      Objective  To clarify the effects of non-genetic factors on the raw milk composition and related traits of Holstein in Ningxia region.
      Method  Based on the DHI data of Holstein in Ningxia region, the effects of parity, lactation stage and calving season on nine lactation traits were analyzed by GLM process of SAS 9.2 software, and the variation characteristics of lactation traits in different somatic cell scores were explored.
      Result  Parity, lactation stage, calving season, lactation stage × calving season had significant effects (P<0.05) on nine lactation traits. Comparison of different parities showed that milk fat percentage and milk solid content decreased significantly after the second parity (P<0.05), milk protein percentage and peak milk yield decreased significantly after the third parity (P<0.05), daily milk yield decreased slightly after the fourth parity, milk lactose percentage decreased first and then increased, reaching the lowest level of 4.84% in the third parity (P<0.05), somatic cell score increased gradually with the increase of parity, and the day of peak milk yield was the latest in the first parity(94.07 d) and the earliest in the fourth parity (67.33 d). Comparison of different lactation stages showed that daily milk yield and milk lactose percentage gradually decreased with the prolongation of lactation in the second and third parities (P<0.05), while milk protein percentage, milk solid content, somatic cell score and milk fat percentage showed an increasing trend (P<0.05). Comparison of different calving seasons showed that from spring to winter, milk fat percentage of the first parity to third parity and milk solid content of the first parity gradually decreased, while daily milk yield and milk lactose percentage showed an increasing trend for the first parity and were at the lowest level in summer for the second parity and third parity. Milk protein percentage, somatic cell score, the day of peak milk yield and peak milk yield showed a trend of increasing first and then decreasing from the first parity to third parity, and the highest levels of all these traits for different parities were found in summer. With the increase of somatic cell score, milk lactose percentage, daily milk yield and peak milk yield decreased gradually, while milk fat percentage and milk protein percentage increased slowly. Milk solid content and the day of peak milk yield reached the highest level when somatic cell score was 4 and 5, respectively.
      Conclusion  The results of this study provide a theoretical basis for improving the lactation performance and fresh milk quality of Holstein in Ningxia.

       

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