Milk yield distribution within pens in commercial dairy farms

VISSIO, CLAUDINA; DERARDO, SOFIA; LARRIESTRA, ALEJANDRO; TURIELLO, PAULA; BARGO, FERNANDO

Indiana

Encuentro; Annual Meeting of the American Association of Dairy Science; 2017

AADS

The knowledge of milk yield distribution (average and standard deviation) is important in diet formulation to avoid the high-producing cows to be underfed. The objective of this experiment was to compare milk yield (MY) distribution using different measurement frequency. We characterized farm and pen MY distribution and compared distributions having monthly or daily records. Individual daily MY records from 2 commercial dairy farms in Argentina from year 2016 were used. Both farms had similar grouping criteria: hospital, fresh, first lactation, high and low producing cows. Hospital pens were excluded from the descriptive analysis. Day 15 of each month was selected arbitrary as the monthly record. Monthly MY were compared to daily MY records in a total of 8 pens (pens with less than 50 cows were not analyzed) from both dairy farms for 12 months using ANOVA of InfoStat. Descriptive statistics for each farm and each pen within farm are presented in Table 1. Although MY was not normally distributed, the median was in average within 0.4 and 0.5 kg of the mean for pens in farm A and B, respectively. Within pen coefficient of variation (CV) was lower than farm variation except for the fresh pens in both farms and the low producing pen for farm B. Pen CV ranged from 22.1 to 35.2% for farm A and from 23.4 to 37.1% for farm B. Pens with higher milk yields tended to have higher SD but lower CV (P=0.08 and P=0.1, respectively). We found differences (P