The Research Column

Four multi-lactation dairy cows in early lactation and subsequently in late lactation were fed two diets for 28 days in a changeover design that provided, within the same stage of lactation, similar amounts of rumen fermentable feed with either high (HS) or low starch (LS). All diets had similar dietary crude protein and rumen-undegradable protein content. Amino acid profiles were similar to that of casein.

Mastitis is the most common disease in dairy cows, causing significant economic effects on milk production and compromising animal welfare. Antibiotic dry cow therapy (aDCT) is an effective way to control mastitis, as cows are susceptible to new within-udder infection at the time of drying-off and again during the immediate post-calving period. Selective dry cow therapy means that only infected or presumed infected cows are treated, instead of dry cow therapy being used as a treatment for all cows.

Listeria monocytogenes is a pathogen which may cause listeriosis with sometimes grave consequences. It is a ubiquitous, gram-positive, facultative anaerobe that grows at refrigeration temperatures and is found throughout the environment, specifically in soil and water. Listeria monocytogenes may survive in food that has a relatively high acid and salt content and can tolerate high and low temperatures.

Colostrum management to provide adequate immunological protection to new born calves has been well investigated, and thresholds for colostrum quality, as well as optimum volume and timing for colostrum feeding have been established. However, less is known about the effect of colostrum from a single dam versus pooled colostrum from several cows on passive immunity, as well as the subsequent antibody survival in the calf.

Oestrus detection has become more difficult over the years due to decreases in the oestrus expression of high-producing dairy cows, and increased herd sizes and animal densities. Through the use of hormonal synchronization protocols, also known as timed artificial insemination protocols, it is possible to alleviate some of the challenges associated with oestrus detection. However, timed artificial insemination masks cows’ fertility performance, resulting in a possibly biased comparison of treated animals and innately fertile animals.

Below par post-calving health has a negative effect on the performance and survival of dairy cows and occurrence of uterine, metabolic and other health disorders which are risk factors for lower subsequent fertility and milk yield, and higher risk of culling. The interrelationship between loss in body condition score (BCS) and disease prevalence is however complex and establishing cause and effect associations is challenging. Increased risk of milk fever, ketosis, fatty liver, metritis, digestive disorders and mastitis in cows with greater loss of BCS after calving has been shown.

Trends in consumer food choices are sometimes spontaneous, not always rational, but nevertheless evoke changes in the food industry. In supermarkets with abundant product choices and information overload on labels, consumers are confused and mostly do not have the background to understand what the information means. Moreover, because of the industrialization of the agri-food industry, consumers lost contact with farm life and are often unfamiliar with the processes behind food production.

Lameness is the clinical condition of impaired locomotion and is caused by a range of foot and leg problems, the most common of which are hoof lesions caused by infectious agents or internal and external forces. It is a leading animal welfare concern in the dairy industry and also has substantive economic consequences, as productivity is decreased through reduced reproduction, milk production and increased culling. Various management practices for preventing lameness and treating lame cows have been developed. Despite this, lameness persists as an industry problem.

In last month’s column, I touched on the use of Saccharomyces cerevisiae fermentation products (SCFP) during the transient phase; the emphasis being on on performance, blood biomarkers, rumen fermentation, and ruminal bacteria population.

The transition period is a critical period for dairy cows, characterized between three weeks before and three weeks after calving. This is a challenging period for dairy cows because of milk genesis, uterine contraction, as well as metabolic and hormonal changes associated with negative energy balance. Yeast products and yeast-containing feed ingredients can be used as a nutritional feed additive to improve health and performance during the transition between pregnancy and early lactation.