W. Jagusiak

Associations between strain, herd size, age at first calving, culling reason and lifetime performance characteristics in Holstein-Friesian cows.

Cow longevity and lifetime performance traits are good indicators of breeding effectiveness and animal welfare. They are also interrelated with the economics of dairy herd. Unfortunately, a high milk yield is often associated with deteriorated cow health and fertility and, consequently, with an increased culling rate. This situation, observed also in the Polish population of Holstein-Friesian cattle, inspired us to undertake a study on the associations between some factors and lifetime performance characteristics. The data set consisted of the records on 135 496 cows, including 131 526 of the Black and White strain (BW), and 3970 of the Red and White strain (RW) covered by performance recording and culled in 2012. It was found that cows of the BW strain and those from the largest herds (>100 cows) reached higher lifetime and mean daily energy-corrected milk (ECM) yields than cows of the RW strain and those from smaller herds culled at a similar age. Cows youngest at first calving (<2.0 years) were characterised by the highest lifetime ECM yield. It indicates that heifers can be bred even when they are younger than 15 to 16 months with no significant negative effect on their later performance. Infertility and reproduction problems (39.6%) and udder diseases (15.5%) constituted the most frequent reasons for cow culling. Cow longevity and lifetime productivity were considerably affected by the interactions between the studied factors.

Recognition of culling reasons in Polish dairy cows using data mining methods

Data mining methods were used to recognize culling reasons in dairy cows.It is impossible to accurately recognize culling reasons using routinely recorded data.More specific data are required to improve the recognition ability of the models. Cow longevity and reasons for culling are one of the most important research problems in the contemporary cattle breeding. Therefore, the analysis of the relationship between cow performance and involuntary disposal contributes to taking more informed decisions in herd management. The aim of the present study was to compare the efficiency of artificial neural networks (ANN) and boosted classification trees (BT) with that of linear discriminant analysis (LDA) and classification functions (CF) in recognizing culling reasons of dairy cows in Poland, based on the lifetime performance data, routinely monitored in a herd. The analyses carried out in the present study showed that the accurate recognition of different culling reasons based on predictors included in the above-mentioned models is, in general, impossible. Only BT had limited discrimination abilities, but the results obtained using this method were not much improved compared with ANN and LDA with CF. In order to predict precisely various culling reasons, more specific data are required. They could be obtained from the increasingly popular, technologically advanced, systems of real-time monitoring of animal health status (physical activity, rumination rate, etc.), dependent also on environmental conditions (e.g. temperature-humidity index).

Analysis of lifetime performance and culling reasons in Black-and-White Holstein-Friesian cows compared with crossbreds

Abstract The effect of crossbreeding Holstein-Friesian cows with other breeds is usually improved genetic potential of crossbreds in terms of longevity. However, culling decisions, which in practice determine the longevity in dairy cows, are contingent on many environmental and economic factors. Therefore, the aim of this study was to evaluate longevity in relation to culling reasons in Holstein-Friesian cows of the Black-and-White strain (HO) and crossbreds, taking genotype, age at first calving, herd size, culling season, culling reason and milking temperament into consideration. The data analysed concerned 154,256 dairy cows culled in Poland in 2015. It was found that all studied factors significantly affected cow lifetime performance. The mean age at culling in dairy cows of HO strain exceeded 6 years, with mean lifetime energy-corrected milk (LECM) yield of 28,933 kg and mean lifetime energy-corrected milk yield per milking day (DECM) of 20.2 kg. Crossbreds, on the other hand, tended to have shorter lifespans, with mean LECM yield amounting to less than 25,000 kg. Mean LECM yield of cows surviving for the longest period (9.2 years), amounted to 47,771 kg, and reproduction problems were unquestionably the most common (40%) reason for cows’ culling. A suggestion was made to take milking temperament into account in breeding practice, as this trait proves to be closely related to the longevity characteristics of dairy cows. It was also proposed that the culling reasons be subjected to a more comprehensive analysis, considering the “life history” of cows as well as the interactions between different reasons for their removal from the herd.

Genetic parameters of conformation traits in young Polish Holstein-Friesian bulls.

Abstract The objective of this study was to estimate the genetic parameters of conformation traits in Polish Holstein-Friesian bulls evaluated for registration in the herd book and for entry into progeny testing. Data were 8 linearly scored (1-9 scale) and 6 composite (scored from 50 to 100) conformation traits of 2,738 young bulls born between 2001 and 2011. The multiple-trait REML method was applied for (co)variance component estimation. The linear model included fixed linear regressions on age at evaluation (from 10 to 23 months), fixed effects of year of birth, fixed effects of herd-classifier, and random animal effect. Heritability estimates for all analysed traits were within the range of 0.04-0.37. Among the 6 composite type traits, heritability was highest for size and for overall conformation score. The lowest heritability was for feet and legs. Among the linearly scored traits, heritability was the lowest for rear legs - side view and foot angle, and the highest for rump angle and muscularity of front end. Composite traits showed the highest genetic correlations with muscularity and final score playing the dominant role. Genetic correlations among linear traits were low and moderate (0.02-0.53). The relatively low genetic and phenotypic correlations indicated that no conformation trait of bulls can be improved by indirect selection alone. More research is needed to establish relationship between bull conformation traits and the conformation of their progeny.

Genetic background of conformation defects in Polish Black-and-White Holstein-Friesian bulls - analysis of phenotypic distribution.

Abstract Phenotypic distribution of 22 routinely evaluated conformation defects was analysed in a population of Polish Black-and-White Holstein-Friesian bulls, sired by different males. Some variation was observed in mean frequency of different morphological defects and in their severity. Large differences were found in frequency of conformation defects and in their number between groups of half-brothers. The most common defects in the bull population analysed were two types of leg defects: wide interdigital space and soft pasterns, which occurred in 199 and 70 animals, respectively. Wide interdigital space was most frequent in 4 groups of half-brothers, in which this defect affected more than 25% of the bulls. The least common defects were the defects of external genitalia, which were found in single animals. The only defect that did not occur was that of testes. The statistical significance of the phenotypic distributions obtained for bull conformation defects was confirmed using the chi-square test of independence and the Fisher-Yates exact test. STRESZCZENIE W literaturze specjalistycznej brak jest prac poświęconych zagadnieniom związanym z genetycznymi uwarunkowaniami wad pokroju buhajów bydła holsztyńsko-fryzyjskiego. Nielicznie prezentowane wyniki badań dotyczące tej tematyki obejmują wyłącznie żeńską część populacji. Biorąc pod uwagę priorytetowe znaczenie ścieżek ojcowskich w programach hodowlanych bydła mlecznego, a zwłaszcza ścieżki ojciec - syn, wskazane jest objęcie takimi analizami krajowej populacji buhajów hodowlanych. Badanie mechanizmu dziedziczenia cech poprzez porównawczą analizę rozkładu fenotypów rodziców i potomstwa jest podstawowym sposobem zdobywania wiedzy o ich genetycznych uwarunkowaniach. W ramach badań analizowano rozkład fenotypowy 22 rutynowo ocenianych wad pokroju w populacji buhajów rasy polskiej holsztyńsko-fryzyjskiej odmiany czarno-białej, pochodzących po różnych ojcach. Wykazano zmienność w średniej frekwencji występowania poszczególnych wad budowy zewnętrznej i stopniu ich nasilenia. Stwierdzono duże zróżnicowanie w częstości występowania wad pokroju oraz ich liczbie pomiędzy grupami półbraci. Dominującymi defektami w analizowanej populacji buhajów są dwa rodzaje wad kończyn: zbyt szeroka szpara racicy oraz miękka pęcina, które wystąpiły odpowiednio u 199 i 70 osobników. W przypadku pierwszej z wymienionych cech stwierdzono wyraźną dominację jej częstości w 4 grupach półbraci, w obrębie których buhaje z tym rodzajem defektu stanowiły powyżej 25%. Najrzadziej występującymi wadami były defekty zewnętrznych narządów rozrodczych, które odnotowano u pojedynczych osobników. Nie stwierdzono występowania jedynie jednej cechy - wady jąder. Statystyczną istotność uzyskanych rozkładów fenotypowych wad pokroju buhajów potwierdzono testem niezależności chi-kwadrat i testem dokładności Fishera-Yatesa. Otrzymane wyniki świadczą także o możliwości podjęcia badań nad oszacowaniem parametrów genetycznych wad pokroju buhajów, których znajomość pozwoliłaby na opracowanie optymalnej strategii selekcji w krajowej populacji bydła holsztyńsko-fryzyjskiego