Evaluation of holstein crossbred bulls based on milk composition of progeny
Loading...
Files
Date
1997
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Department of Animal Breeding and Genetics, College of Veterinary and Animal Sciences, Mannuthy
Abstract
Sire evaluation programmes in Kerala state, so far have been hinged
around milk production alone, and no emphasis has been laid on milk
constituents. The milk constituents like fat and solids not fat determined the
market value and consumer's receptivity of milk. Reports on sire evaluation on
the basis of milk constituents were seriously lacking in literature and hence the
present investigation was undertaken with a view to compare the crossbred
sires on the basis of milk yield, fat, total solids, and solids not fat percentages
and their yields.
1284 milk samples belonging to 222 animals (103 progenies of Holstein
crossbred bulls with superior genetic worth and 119 contemporaries) calved
during the period 1995~96 formed the material for the study. These animals
belonged to farmers in the area of six AI centres around Thrissur and also the
animals maintained in three University Livestock farms. Milk samples were
collected during early, middle and late lactation both in morning and evening,
and the samples were analysed for fat, total solids and solids not fat
percentages. Milk fat percentage was estimated by Electronic Milk Tester with
frequent standardisation with Gerber's method. Total solids percentage was
determined by Gravimetric method and solids not fat by finding the difference
between total solids and fat percentages of milk. Fat, total solids and solids not
fat yields were calculated by multiplying the percentages of these constituents
with cumulative milk yield for each stage for lactation and adding.
--
The statistical analysis was done as per standard procedure. Least
squares technique as described by Harvey (1986) was employed to analyse the
effects of centre, sire and season on the characters studied. The effect of
centre was highly significant, while effects of sire and season were non-
significant.
The overall average 305 day milk yield was found to be 1829.68 kg. The
progenies in the first lactation had higher averages compared to the
contemporaries in different parities. Among the centres progeny average of
305 day milk yield was maximum for University Livestock Farm, Mannuthy
(2800 kg) followed by Ramavarmapuram (2426.71 kg).
University farm milk samples revealed higher values for 305 day milk
yield, fat, total solids and solids not fat percentages compared to field milk
samples. Among the centres, Arimbur recorded comparatively higher fat
percentages during all stages of lactation.
An important result from legal point of view was that,66.67 per cent of
cows in the early stage of lactation, recorded morning milk fat per cent below
the legal standards of 3.5. In case of solids not fat, 46.5 per cent were below
the PFA standard of 8.5 per cent.
Total solids and fat percentage showed an increasing trend with the
progress of lactation. But such a trend was not observed for solids not fat
percentage.
Heritability estimates were calculated by paternal half-sib method for milk
yield and its composition. Milk fat percentage had the highest heritability
estimate of 0.326iO.234.
The estimates of sire merit of Holstein Friesian test bulls for 305 day milk
yield.fat, total solids and solids not fat percentages and yields, were computed
by three methods of sire evaluation viz., daughter's average, contemporary
comparison and least squares means. The yield characteristics were found to
have more genetic variance than the corresponding percentages and hence
preferred for sire evaluation. Since there was slight difference in the ranking
of sires by these methods there is a need to study the accuracy of evaluation
by different methods and then to choose the best method for evaluation under
field conditions. The observation on the low milk fat and solids not fat
percentages pinpoints the necessity of urgently amending PFA act for the
benefit of the farmers.
Description
PG
Keywords
null
Citation
171440