The Research Column

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.

Whole milk powder is an important product that is often exported to be reconstituted and used for various purposes. The spray drying to obtain the product enables milk to be easily transported and stored for extended periods of time. However, the spray drying process can also facilitate oxidative changes as the high fat content is exposed to elevated temperatures, resulting in reduced shelf life due to off-flavour development. Moreover, whole milk powder can also be subjected to extreme temperature fluctuations during transport and storage, further affecting oxidative stability.

The environmental impact of producing animal source foods is a critical topic of policy discussion in domestic and international governments, social media, the popular press, and the consumer marketplace. Livestock’s contribution to the environmental impacts associated with food production are significant concerns for all food chain stakeholders, including livestock producers who play a major role in reducing environmental impacts per unit of food.

Although limited in South Africa, many dairy cattle worldwide are still housed in tiestalls, meaning that they are tethered by the neck to individual stalls. On some farms, tied cattle are permitted seasonal access to pasture, but otherwise their movements are restricted compared with cows housed in freestall barns or other loose housing systems. The aim of the systematic review by Dr A Beaver and colleagues was to summarize the scientific literature pertaining to the welfare of tied dairy cattle through comparison with less-restrictive housing systems.

The environmental effects of mineral nitrogen are of global concern, and there is growing determination to mitigate its use for agricultural purposes. The replacement of synthetic fertilizer N with N fixed by bacteria (biological N fixation) in association with legumes such as white clover (Trifolium repens L.) offers the potential to lower fertilizer N use, nitrous oxide and ammonia emissions, and energy use.