Evaluation of holstein crossbred bulls based on milk composition of progeny
| dc.contributor.advisor | Sosamma Iype | |
| dc.contributor.author | Radhika, G | |
| dc.contributor.author | KAU | |
| dc.date.accessioned | 2019-05-16T05:20:46Z | |
| dc.date.available | 2019-05-16T05:20:46Z | |
| dc.date.issued | 1997 | |
| dc.description | PG | en_US |
| dc.description.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. | en_US |
| dc.identifier.citation | 171440 | en_US |
| dc.identifier.uri | http://krishikosh.egranth.ac.in/handle/1/5810103329 | |
| dc.keywords | Animal husbandry, crossbred bulls, animal breeding and genetics, least square analysis | en_US |
| dc.language.iso | en | en_US |
| dc.publisher | Department of Animal Breeding and Genetics, College of Veterinary and Animal Sciences, Mannuthy | en_US |
| dc.sub | Animal Genetics and Breeding | |
| dc.subject | null | en_US |
| dc.theme | Holstein crossbred bulls | en_US |
| dc.these.type | M.V.Sc. | en_US |
| dc.title | Evaluation of holstein crossbred bulls based on milk composition of progeny | en_US |
| dc.type | Thesis | en_US |