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Milk fat and protein yield in Holstein California herds with different milk production levels.

M. B. Abreu




Milk fat and protein yield in Holstein California herds with different milk production levels.
M. B. Abreu*1,2, M. I. Marcondes1, F. C. Ferreira2, B. Verboort3, N. Silva-Del-R�o2. 1Universidade Federal de Vicosa Vicosa, MG, Brazil, 2Veterinary Medicine Teaching and Research Center, University of California-Davis Tulare, CA, 3Agritech Analytics Visalia, CA.

The objective of the present study was to benchmark milk components (fat and protein) across Holstein California dairy herds with different milk production levels (MPL). Dairy Herd Improvement Association records from 2017 were obtained from Agritech Analytics (Visalia, CA). The initial data set included information from 343 herds, 572,893 cows, and 3,182,862 milk tests. Data was screened using proc Means of SAS. The effect of MPL on milk components was evaluated using the GLIMMIX of SAS. Least squares means were considered different when P ≤ 0.05. The final data set included herds with ≥200 cows and >5 mo test, and cows with until 200 d in milk (DIM). Cow observations with <2% or >6% of fat and protein content, and milk yield ≥ 10 kg were considered outliers. After data screening, the final data set include 238 herds, 462,550 cows, and 1,830,884 milk tests. Herds were classified according to MPL as low (LP; 1: < 32 kg; n = 59), medium (MP; Q1 ≤ to ≤ Q3: 32 ≤ to ≤38 kg; n = 118), and high (HP; > Q3: > 38 kg; n = 61) production level. On average, the final enrolled herds had 2,763, 2,365, and 2,882 cows and produced 31, 39, 43 kg/d respectively for LP, MP, and HP. Milk fat (%) [4.39% (LP); 3.64% (MP); 3.63%(HP)] and milk protein (%) [3.47%(LP) 3.07%(MP); 3.02%(HP)] significantly decreased as MPL increased. However, average milk fat yield (kg/cow/d) [1.31 (LP); 1.40 (MP); 1.58 (HP)] and protein yield (kg/cow/d) [1.03 (LP); 1.19 (MP); 1.31 (HP)] significantly increased as MPL increased. There was a significant effect of the month and a month by MPL interaction for milk fat and protein (%). For the top 10 fat and protein producing herds (9 HP, 1 MP), fat per cow ranged from 1.66 to 1.84 kg/d (3.46 to 3.86%) and protein per cow 1.37 to 1.59 kg/d (2.93 to 3.24%) respectively. In conclusion, although LP herds had the greatest association with milk fat and protein content, HP herds showed greatest association with milk fat and protein yield.

Keywords: milk production level, milk components, California dairies.