The paper reviews the various factors affecting dystocia in cattle. It is based mainly on the recent studies found in the literature of the subject but refers occasionally to some older papers as well. The factors are grouped into four main categories: direct factors, phenotypic factors related to calf and cow, non-genetic and genetic factors. The first group includes malpresentations and uterine torsion. The second one includes: calf birth weight, multiple calvings, perinatal mortality, cow pelvic area, cow body weight and body condition at calving, gestation length. The non-genetic factors are: cow age and parity, year and season of calving, place of calving, maintenance practises, disorders, calf sex and nutrition. Other non-genetic factors are the level of hormones in the periparturient period, in vitro production of embryos and embryo cloning. Finally, the genotypes of cow, bull and calf, inbreeding, muscular hypertrophy, selection and quantitative trait loci form the fourth group of genetic factors.

SummaryAssociations between polymorphism of the bovine growth hormone (GH) gene (Leu/Val) and milk production traits of Black-and-White cattle with different proportional share of Holstein Friesian genes were analysed. A total of 1086 cows were included in the study. PCR-RFLP method was used for genotyping. The frequencies of genotypes and alleles were as follows: 0.653 for LL genotype, 0.324 for LV and 0.023 for VV, and 0.815 for GH L and 0.185 for GH V . Associations between Leu/Val polymorphism and milk production traits of cows were found only in first lactation. Cows with LL genotype had higher milk, fat and protein yield compared to LV individuals (P ≤ 0.01).

Non-ruminants Full-length research article Optimization of solid-state fermentation conditions of Bacillus licheniformis and its effects on Clostridium perfringens-induced necrotic enteritis in broilers ABSTRACT-In the present study, we examined the growth parameters of Bacillus licheniformis in solid-state fermentation (SSF) and evaluated the effects of Bacillus licheniformis-fermented products on Clostridium perfringens-challenged broilers. During four and six days of SSF, the highest viable biomass was observed at 5% glucose, 10% soybean meal, 3% yeast, and 50% initial moisture content. The Bacillus licheniformis SSF products were heat-and acid-resistant. Furthermore, the fermented products were able to inhibit the growth of Clostridium perfringens and Staphylococcus aureus in vitro. In feeding experiments, in a similar manner to the antibiotic treatment group, dietary supplementation of Bacillus licheniformis-fermented products significantly improved intestinal morphology and necrotic lesions under Clostridium perfringens challenge, accompanied by increased IFN-γ mRNA expression in the spleen and bursa of Fabricius. These results together suggest that Bacillus licheniformis-fermented products have potential for development as feed additives and use as possible substitutes for antibiotics to treat Clostridium perfringens in the poultry industry.

Associations between polymorphism localised in the third exon of the prolactin gene (PRL-RsaI) and milk production traits of Black-and-White and Jersey cattle were analysed. A total of 427 cows were included in the study. PCR-RFLP method was used. The frequencies of genotypes and alleles were as follows: 0.7107 -AA, 0.2851 -AB, 0.0042 -BB; 0.8533 -PRL A and 0.1467 -PRL B for Black-and-White cattle and 0.0919 -AA, 0.4324 -AB, 0.4757 -BB; 0.3081 -PRL A and 0.6919 -PRL B for Jersey cattle. Statistically significant differences between the breeds were observed in the frequencies of genotypes and alleles. Associations between PRL-RsaI polymorphism and milk production traits of Jersey cows and lack of associations with these traits in Black-andWhite cows were observed.

Swine dysentery and necrotic enteritis are a bane to animal husbandry worldwide. Some countries have already banned the use of antibiotics as growth promoters in animal production. Surfactin is a potential alternative to antibiotics and antibacterial agents. However, the antibacterial activity of Bacillus species-derived surfactin on Brachyspira hyodysenteriae and Clostridium perfringens are still poorly understood. In the current study, the antibacterial effects of surfactin produced from Bacillus subtilis and Bacillus licheniformis on B. hyodysenteriae and C. perfringens were evaluated. Results showed that multiple surfactin isoforms were detected in B. subtilis, while only one surfactin isoform was detected in B. licheniformis fermented products. The surfactin produced from B. subtilis exhibited significant antibacterial activity against B. hyodysenteriae compared with surfactin produced from B. licheniformis. B. subtilis-derived surfactin could inhibit bacterial growth and disrupt the morphology of B. hyodysenteriae. Furthermore, the surfactin produced from B. subtilis have the highest activity against C. perfringens growth. In contrast, B. licheniformis fermented product-derived surfactin had a strong bacterial killing activity against C. perfringens compared with surfactin produced from B. subtilis. These results together suggest that Bacillus species-derived surfactin have potential for development as feed additives and use as a possible substitute for antibiotics to prevent B. hyodysenteriae and C. perfringens-associated disease in the animal industry.