Abstract #T178

# T178
Milk yield distribution within pens in commercial dairy farms.
P. Turiello*1, C. Vissio1,2, S. Derado Mulleady1, F. Bargo3, A. Larriestra1, A. Relling4, 1Universidad Nacional de Río Cuarto, Río Cuarto, Córdoba, Argentina, 2CONICET, Río Cuarto, Córdoba, Argentina, 3Universidad de Buenos Aires, Buenos Aires, Argentina, 4Ohio State University, Wooster, OH.

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 with daily MY records in a total of 8 pens (pens with less than 50 cows were not analyzed) from both dairy farms for 12 mo 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 < 0.05) between monthly and daily MY records 30.2% of the times analyzed (29 times, between 2 and 6 mo/year in every pen). Daily average MY was lower than monthly data in 34.5% of those comparisons. Further analysis of milk yield distribution is needed to improve grouping strategies and to make recommendations regarding data collection and diet adjustments frequency. Table 1. Milk yield distribution summarized by farm
Milking cowsPensMean milk yield, kg (SD)Range in mean pen milk yield (kg)Range in pen SD (kg)
Farm A480427.9 (8.74)19.7–32.35.67–9.30
Farm B1505832.1 (8.02)25.0–44.37.12–12.11

Key Words: milk distribution, diet formulation, grouping