No abstract

The Ovsynch program may provide a useful treatment option for NVO cows within seasonally-calving pasture-based dairy herds.

Aims:  To identify and characterize the major lactic acid bacteria in the rumen of dairy cattle grazing improved pasture of rye grass and white clover and receiving a maize silage and grain supplement with and without virginiamycin. Methods and Results:  Eighty‐five bacterial isolates were obtained from the rumen of 16 Holstein‐Friesian dairy cows. The isolates were initially grouped on the basis of their Gram morphology and by restriction fragment length polymorphism analysis of the PCR amplified 16S rDNA. A more definitive analysis was undertaken by comparing the 16S rDNA sequences. Many of the isolates were closely related to other previously characterized rumen bacteria, including Streptococcus bovis, Lactobacillus vitulinus, Butyrivibrio fibrisolvens, Prevotella bryantii and Selenomonas ruminantium. The in vitro production of l‐ and/or d‐lactate was seen with all but five of the isolates examined, many of which were also resistant to virginiamycin. Conclusion:  Supplementation of grain with virginiamycin may reduce the risk of acidosis but does not prevent its occurrence in dairy cattle grazing improved pasture. Significance and Impact of the Study:  This study shows that lactic acid production is caused, not only by various thoroughly researched types of bacteria, but also by others previously identified in the rumen but not further characterized.

The combination of a low payload (1.0 g) progesterone releasing intravaginal device with eCG treatment at device removal within a GPG treatment is a clinically effective treatment for anoestrous in New Zealand dairy cows.

Errors associated with pre-mating heat detection are likely to result in between 15 to 30% of cycling cows not detected in oestrous before mating, resulting in the inclusion of cycling cows within the population of non-cycling cows. This mixed population of cows is then subjected to manual examination by veterinarians in order to assign cows to treatment groups. The corpus luteum test has modest sensitivity and high specificity and the size test has high sensitivity and low specificity. Therefore the use of a single examination of the ovaries of cows not detected on heat before the mating period, in order to classify them as anovulatory anoestrous cows with or without a corpus luteum, is not sufficient to accurately classify them and thus to recommend treatment.