Τετάρτη, 14 Φεβρουαρίου 2018

Early-life events associated with first-lactation performance in pasture-based dairy herds

Publication date: Available online 13 February 2018
Source:Journal of Dairy Science
Author(s): G.M. Chuck, P.D. Mansell, M.A. Stevenson, M.M. Izzo
This was a prospective cohort study to determine how events from birth until first calving affect performance during the first lactation in pasture-based dairy herds in Victoria, Australia. Events during the preweaning (0–84 d), prepubertal (85–473 d), and postpubertal (474–804 d) periods were recorded in 6 herds, and their association with first-lactation 100-d and 250-d total milk, fat, and protein yields was quantified. Predictors of first-lactation performance included passive transfer status as a calf; season of birth; age of dam; the presence or absence of dystocia at the time of the heifer's birth; the presence or absence of preweaning diarrhea; preweaning, prepubertal, and postpubertal average daily weight gain; age at first calving; the presence or absence of periparturient disease at first calving; sex of the first-born calf; the presence or absence of a stillborn calf at the first calving; and requirement of assistance at the first calving. Lactation performance was quantified using cumulative 100-d and 250-d milk, fat, and protein yields estimated from herd recording. A multivariable linear regression model was developed for each outcome: cumulative 100-d milk, fat, and protein yield and cumulative 250-d milk, fat, and protein yield. Heifers that experienced dystocia at the time of their birth produced 7.6 kg [95% confidence interval (CI): 1.8–13.3] less fat and 4.8 kg (95% CI: 0.6–8.9) less protein at 100 d in milk in the first lactation compared with heifers that were delivered without dystocia. Heifers born in the summer and autumn produced 20 L (95% CI: 0.8–40) more milk and 20 kg (95% CI: 5.9–33) more protein at 250 d in milk in the first lactation compared with heifers born in the spring. For 100 g/d increases in prepubertal average daily gain, heifers produced an additional 182 L (95% CI: 149–216) of milk, 4.1 kg (95% CI: 2.8–5.5) of fat, and 4.0 kg (95% CI 3.1–5.0) of protein at 100 d in milk and an additional 345 L (95% CI 264–425) of milk, 6.1 kg (95% CI 3.2–9.0) of fat, and 7.5 kg (95% CI 5.3–9.7) of protein at 250 d in milk. Postpubertal average daily gain was positively associated with 100-d milk yield and 250-d milk yield and protein production. We conclude that of all the growth periods assessed in this study, events that occurred during the prepubertal period (85–473 d of age) had the greatest effect on first-lactation performance.



from #AlexandrosSfakianakis via Alexandros G.Sfakianakis on Inoreader http://ift.tt/2Es7Mvq
via IFTTT

Δεν υπάρχουν σχόλια:

Δημοσίευση σχολίου

Δημοφιλείς αναρτήσεις