No abstract

Isolation of genomic DNA is one of the basic steps in many different molecular analyses. There are a few reports on methods of DNA isolation from milk, but many of them are time consuming and expensive, and require relatively large volumes of raw milk. In this study a rapid, sensitive, and efficient method of DNA extraction from milk somatic cells of various mammals (cattle, sheep, goats, horses) is presented. It was found that milk is a good source of genomic DNA, and to obtain a sufficient amount and quality of DNA, suitable for molecular analysis such as PCR, 10 mL of raw milk is sufficient. Thanks to this method, stress in animals can be reduced during collection of researched material. Therefore, this method could be widely used in molecular analyses.

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.

Random regression models (RRM) have recently been used not only in the analysis of milk traits such as milk, fat and protein yield, but also somatic cell score (SCS), lactose yield and milk urea nitrogen (MUN), and very seldom they have been applied to analyze milk dry matter (DM) yield. RRM have many advantages over lactation models: 1) they account more accurately for environmental factors affecting the performance of cows in each day in milk (DIM) throughout the lactation, 2) they allow ABSTRACT: The objective of this research was to examine heritabilities and genetic, phenotypic and permanent environmental relationships between milk dry matter (DM) and milk traits such as milk, fat, protein and lactose yields, milk urea nitrogen (MUN) and somatic cell score (SCS) in extended (to 395 days) lactations of Holstein cows from a big farm in Poland. The data set consisted of 78 059 test day records from the first, second and third lactations of 3 792 cows, daughters of 210 sires and 1 677 dams. Single-or two-trait random regression models were used with fixed effects of calving year, calving month, dry period and calving interval and random additive genetic and permanent environmental effects. The last two fixed effects were not included in the analysis of first lactation data. The highest values of heritabilities for all traits, except DM, were observed in the second lactation. First lactation heritabilities for all traits -except milk yield and SCS -were smaller than those in the third lactation. Lactose yield was highly heritable, with average h 2 equal to 0.25, 0.29 and 0.28 in lactations 1, 2 and 3, respectively. Heritability for DM was slightly lower than that for lactose (0.22, 0.26 and 0.28 for lactations 1, 2 and 3, respectively). In all lactations heritabilities for SCS were below 0.1. Genetic correlations between DM and milk yield (0.64-0.74) were lower than those between MUN and milk yield (0.67-0.79) as well as between lactose and milk yield (0.72-0.82). In general, DM was much more closely correlated with fat or protein yield (0.55-0.79) than with MUN or lactose (0.38-0.76). Only in the third lactation the correlation between DM and protein (0.72) was lower than between lactose and protein (0.76). For all lactations there were very high genetic correlations between DM and lactose (0.96-0.98) and high correlations between ) and between lactose and MUN (0.70-0.85). The results suggest that further research is needed, focused on DM and its relationship with other traits in larger populations.

No abstract

Agroecology represents a pertinent option to improve the sustainability of agriculture. To promote its application, agroecological concepts should be taught to students and professionals in the agricultural sector. However, most agricultural courses are not adapted to teach these concepts due to little interactivity or interdisciplinarity, and a lack of a systems approach to farm management. Serious games help to fill these gaps by simulating complex models in which players can learn by doing. We thus developed a serious computer game, called SEGAE (SErious Game for AgroEcology learning), which represents a mixed crop-livestock farm and assesses impacts of farming practices on indicators related to environmental, economic, and social sustainability. Its pedagogical interest was evaluated through two types of surveys given to university students who played the game during a one-week workshop: A knowledge survey on agroecology, and a feedback survey based on flow theory. Results showed that students increased their knowledge of agroecology significantly, particularly those who had had little knowledge of crop production. More than 86% of the students enjoyed the game, appreciating its interaction and feedback. Thus, SEGAE is an interesting tool to help students acquire knowledge of agroecology in a fun way by facilitating interdisciplinary and collaborative learning.

Contents: Repeatability and heritability coefficients were estimated for ejaculate volume, mass movement, individual motility, sperm concentration, first and second post‐freezing control of motility, number of doses frozen, total number of spermatozoa and total number of motile spermatozoa per ejaculate in the first ten ejaculates of 175 Swiss Holstein and 673 Simmental young bulls (200 pure Simmental, 473 Simmental x Red Holstein crosses). Data were analysed using the univariate individual animal model with effects of interval between consecutive collections, age of bull at collection, season of collection, breed group of Simmental bulls according to percentage of Red Holstein genes, bull (within breed group) and permanent environment. Crossbred bulls had a better performance in all traits. Repeatability coefficients ranged from 0.28 to 0.46. They indicate that the prediction of semen quality in young bulls of the Swiss Holstein and the Simmental breed is possible to some extent. Heritabilities in Swiss Holstein bulls were generally very low and did usually not exceed 0.10, but standard errors of these estimates were high. Relatively high heritabilities (0.18–0.30) were found for Simmental bulls, Differences in heritabilities between these two breed groups were probably a consequence of the low number of Swiss Holstein bulls.

Bovine mastitis is a widespread disease of the mammary gland, highly contributing to the increase in veterinary costs in dairy industry. In the present study, the genetic polymorphism within bovine L-selectin gene was analysed and its impact on clinical mastitis occurrence, somatic cell score (SCS), and milk production traits in Polish Holstein-Friesian cows was examined. Polymorphism within L-selectin gene, molecule responsible for neutrophil attachment to endothelium, might have a potential role in immune response to bacterial infections and udder health. Two hundred and six Polish Holstein-Friesian cows were genotyped by polymerase chain reaction-restriction fragment length polymorphism method. Two single nucleotide polymorphisms mutations within the coding sequence of L-selectin gene were identified (c.165G&gt;A and c.567C&gt;T). The effect of c.165G&gt;A and c.567C&gt;T mutations on SCS was highly significant (P = 0.0019 and P = 0.0003, respectively). Strong associations (P ≤ 0.0001) were also observed between L-selectin polymorphism and milk production traits (milk yield, milk fat percentage, and milk protein percentage). However, the polymorphism in the analysed gene had no influence on the resistance or susceptibility of cows to clinical mastitis (only the tendency toward significance, P = 0.06 for c.567C&gt;T mutation was found). Potential exploitation of the information on the identified associations in genetic selection needs to confirm the obtained results in further investigations.