Abortion lactation curves

PICCARDI, M.; CAPITAINE FUNES, A.; BÓ, G.; BALZARINI, M.

Pittsburgh

Congreso; ADSA 2017; 2017

ADSA

The aim of this study was to establish if there is an association between the type of lactation (gestation at term vs. abortion) and the parity period (warm vs. cool) for each animal category (primiparous cows and multiparous cows). Data were analyzed through a Pearson´s chi-squared test using the statistical software InfoStat. In addition, to compare the lactation curves started withabortions versus lactation started with gestations at term, a nonlinear model (MilkBot) was adjusted considering the subject-specific effect given by the cow. Lactations were classified by parity period and partitioned by animal category. We used PROC NLMIXED from SAS to estimate the cumulative milk yield at 305 days in milk (305dMY) and the peak milk yield (PMY). Finally, for each category animal, 305dMY and PMY were compared with an analysis of variance using Fischer´s LSD test. In the model, lactation type and parity period and his interaction were considered as the independent variables. The database was composed of a total of 8,479 closed lactation from gestation at term (144,851 milk test) and 422 closed lactation initiated from abortions (4,075 milk test). We conclude that there is a significant association between lactation type and parity period for each animal category (p≤0.05). Within primiparous cows, the odds ratio of starting a lactation with an abortion were 2.02 times higher in warmer period versus in cool period (p=0.0006). Within multiparous cows, the odds ratio of starting a lactation with an abortion were 1.52 times higher in warmer period versus in cool period (p=0.0006). For primiparous and multiparous cows 305dMY and PMY were significantly higher in cows that had gestation at termthan cows that had an abortion (Differences in 305dMY: primiparous: 869 l; p<0.0001, multiparous: 2,062 l; p<0.0001; Differences in PMY: primiparous: 4 l/d; p<0.0001, multiparous: 8 l/d; p<0.0001). The effect of parity period and the interaction with type of lactation depends on animal category. For primiparous cows, the 305dMY and PMY were less in warmer period in both type of lactation. Whereas for multiparous cows, 305dMY and PMY were less in warmerperiod in cows who had calved in term, but were greater in cows who had Experimented an abortion.