TITLE:
Performance of Dairy Cows Supplemented with By-Pass Fat under Heat Stress Conditions
AUTHORS:
Pablo Matías Roskopf, María Paz Tieri, Alejandra Cuatrin, María Esperanza Ceron Cucchi, José Ignacio Gere, Eloy Eduardo Salado
KEYWORDS:
Dairy Cattle, By-Pass Fat, Heat Stress
JOURNAL NAME:
Open Journal of Animal Sciences,
Vol.13 No.1,
January
9,
2023
ABSTRACT: The objective of this study was to determine the
effect of supplementation with a protected fat source on the productive
response, metabolic environment and physiological indicators in Holstein cows
under heat stress conditions during a 12-week experimental period. Thirty
Holstein cows were distributed in 15 blocks by parity (2.0 ± 1.1), days in milk
(182 ± 80) and milk production (29.4 ± 5.7 kg·day-1) at the beginning of the trial and randomly assigned within each block to the following treatments (diets): SPF:
supplementation with protected fat or WPF: without supplementation with
protected fat. All the cows were kept in a dry-lot where they were given a
partial mixed ration (PMR) ad libitum while in the milking parlor they
received individual supplementation depending
on the treatment. The SPF diet contained 4.0 kg·day-1 concentrate in pellet form +
0.6 kg·day-1 ground corn grain + 0.7 kg·day-1 protected fat, while the WPF
diet was similar to that offered in SPF, but the protected
fat was isoenergetically replaced by ground corn grain. The fat supplement
contained fats of animal and vegetable origin and microencapsulation was used
for its preparation. Total dry matter and metabolic energy intakes were similar (p > 0.05) between
treatments. Fat corrected milk (4% FCM) production was higher (p = 0.04), while
energy corrected milk and fat productions tended (p = 0.06) to be higher in
cows from the SPF group, without effects (p > 0.05) on the rest of
the milk production and composition parameters. These results could be attributed
to an improvement in the efficiency of the use of the energy consumed. Protected fat supplementation neither modified the metabolic profile, nor reduced the
respiratory rate and body temperature of heat-stressed cows. Future research is
needed to explain this latter result.