Estimation of the breeding value and ranking of Holstein-Friesian bulls on fertility properties

Abstract

The analysis included 433 daughters of 10 bulls, calving for the first time in the period from 2007 to 2014, on 6 dairy farms of the Agricultural Corporation Belgrade AD. Fixed factors included in the model were the effects of the farm, year of calving and calving season, and as a random factor the impact of the bull sire. The observed fertility properties on the basis of which breeding values were calculated were the number of days of gestation, the age at the first insemination, the service period duration and the calving interval. Bulls were ranked on the basis of these properties and using the Spearman correlation coefficient, the degree of agreement between the ranks was determined. According to the breeding values calculated by using the Best Linear Unbiased Prediction (BLUP) method, the sire 1517 was best ranked for the trait duration of service period (-34,94 days) and the calving interval (-36,14 days), relative to the average of daughters. The effects of the farm and year of calving showed no significance (p>0.05) except on the duration of the gestation. The effect of the calving season showed a very high significance (p lt 0.001) for the following properties: age at first insemination, duration of the service period and calving interval, as well as significance (p lt 0.05) for the property duration of the gestation. A statistically very significant degree of agreement between the service period and the calving interval of 0.99** (p lt 0.01) was determined by the Spearman coefficient of correlation, while there was no significant difference between the other properties (p>0.05).

U analizu je uključeno 433 prvotelke, kćeri 10 bikova, prvi put oteljene u periodu od 2007. do 2014. godine, na 6 farmi krava Poljoprivredne korporacije Beograd AD. Kao fiksni faktori u modelu, uključeni su: uticaji farme, godina telenja i sezona telenja, i kao slučajan faktor uticaj bika oca. Praćene osobine plodnosti na osnovu kojih su izračunate priplodne vrednosti su: broj dana bremenitosti, uzrast pri prvom osemenjavanju, dužina servis perioda i međutelidbeni interval. Bikovi su rangirani na osnovu pomenutih osobina, a primenom Spirmanovog koeficijenta korelacije utvrđen je stepen slaganja između rangova. Prema izračunatim priplodnim vrednostima metodom najboljih linearnih objektivnih pokazatelja (Best Linear Unbiased Prediction - BLUP) utvrđeno je da je bik otac, broj 1517 je najbolje rangiran za osobine trajanje servis perioda (-34,94 dana) i međutelidbenog intervala (-36,14 dana) u odnosu na prosek kćeri.Uticaji farme i godine telenja nisu pokazali značajnost (p>0,05) samo kod osobine trajanje bremenitosti. Uticaj sezone telenja je pokazao vrlo visoku značajnost (p lt 0,001) za osobine: uzrast pri prvom osemenjavanju, dužina servis perioda i međutelidbeni interval, kao i značajnost (p lt 0,05) na osobinu trajanje bremenitosti. Spirmanovim koeficijentom korelacije utvrđen je statistički vrlo značajan stepen slaganja između trajanja servis perioda i međutelidbenog intervala (p lt 0,01), dok između drugih osobina nije bilo značajnosti (p>0,05).