Non-genetic sources of variance of milk productivity traits in Bulgarian Murrah buffalo cows
Georgi Nonchev, Yordanka Ilieva, Pencho Penchev
Резюме: With the aim to study the non-genetic effects on milk yield per normal lactation and fat and protein
percentage in milk, was conducted analyses of variance in buffalo cows from two different farming
systems for the period 2007–2020. From farm FM-1 were included 340 lactations of 173 buffaloes
housed tie-stall with a yard, and from FM-2 – 364 lactations of 63 buffaloes farmed tie-stall with
available pasture from April to October. The software products LSMLMW and MIXMDL (Harvey,
1991) were used, the linear models including the fixed effects of farm, period, season of calving,
parity, as well as age of first calving (AFC) or days open. The significance of the factor parity on milk
yield in the overall dataset (P < 0.001) and its non-significance for the pluriparous buffaloes render
a difference expressed in lowest productivity of first lactation. Of the two environmental factors,
only period is significant (P < 0.001), while the effect of season is not. Farm affects milk yield in all
datasets. AFC has no influence but days open is significant source of variation of milk yield (P < 0.05),
the highest LSM belonging to the buffaloes conceiving 1.5–3.5 months postpartum. Fat percentage is
significantly affected by parity – both in overall dataset (P < 0.05) and in adult buffaloes (P < 0.05),
second lactation marked by lowest LSM. Farm and period have highly significant effect on fat content
in both primiparous and pluriparous animals. In contrast to AFC, days open affects fat percentage
(P < 0.01), the highest LSM belonging to the cases of conception up to day 50 postpartum. With the
exclusion of parity (P > 0.05), the same effects define the variance of the trait protein content of milk
– farm and period at P < 0.001 and days open at P < 0.05.
percentage in milk, was conducted analyses of variance in buffalo cows from two different farming
systems for the period 2007–2020. From farm FM-1 were included 340 lactations of 173 buffaloes
housed tie-stall with a yard, and from FM-2 – 364 lactations of 63 buffaloes farmed tie-stall with
available pasture from April to October. The software products LSMLMW and MIXMDL (Harvey,
1991) were used, the linear models including the fixed effects of farm, period, season of calving,
parity, as well as age of first calving (AFC) or days open. The significance of the factor parity on milk
yield in the overall dataset (P < 0.001) and its non-significance for the pluriparous buffaloes render
a difference expressed in lowest productivity of first lactation. Of the two environmental factors,
only period is significant (P < 0.001), while the effect of season is not. Farm affects milk yield in all
datasets. AFC has no influence but days open is significant source of variation of milk yield (P < 0.05),
the highest LSM belonging to the buffaloes conceiving 1.5–3.5 months postpartum. Fat percentage is
significantly affected by parity – both in overall dataset (P < 0.05) and in adult buffaloes (P < 0.05),
second lactation marked by lowest LSM. Farm and period have highly significant effect on fat content
in both primiparous and pluriparous animals. In contrast to AFC, days open affects fat percentage
(P < 0.01), the highest LSM belonging to the cases of conception up to day 50 postpartum. With the
exclusion of parity (P > 0.05), the same effects define the variance of the trait protein content of milk
– farm and period at P < 0.001 and days open at P < 0.05.
Ключови думи: buffaloes; fat; milk yield; non-genetic factors; protein; variability
Дата на публикуване: 2022-02-25
Свали пълен текст