The Research Column

Dairy cattle often experience negative energy balance during the calving transition period, because of reduced feed intake and a drastic increase in nutrient demands after the onset of lactation, thereby contributing to high risk of metabolic disease and low immunity. This implies that feeding strategies during the calving transition period should be designed to maintain feed intake to mitigate excessive fat mobilization.

Standardization of terminology is important as people often develop definitions which  the meaning thereof is not recognized or understood by others, or they use one term for different activities or functions. One such term is culling which is used in different ways leading to confusion or misinterpretation. To address this Dr J. Fetrow and colleagues were commissioned by the American Dairy Science Association to address the confusion and come up with recommendations.

The crossing of parents of unrelated strains, or breeds, often results in offspring that are more robust, with better health, growth, fertility, and production. In dairy cattle, crossbreeding has also been shown to improve functional traits such as fertility, health, calving ability, and survival. Despite the compelling evidence of the benefits of crossbreeding, the majority of dairy farmers still prefer traditional pure breeding, and crossbreeding in dairy cattle is far from common.

Successful reproductive performance is the basis for profitable dairy farming. Poor reproductive performance results in increased calving intervals and decreased milk production, and therefore significant economic losses to the farmer.

Technological advancements allow dairy farmers to increase the efficiency of use of land, labour, and capital to produce milk. Automatic milking systems (AMS) offer the possibility to increase productivity and profitability by potentially improving labour efficiency, milk production, animal welfare, and lifestyle.

To try and improve the efficiency of protein use in dairy production has been the goal of many studies in the past 40 years. Lower dietary protein with the same milk protein output should increase protein efficiency and profitability. However, reduced production is a potential risk of feeding diets with less protein, as feeding less protein may reduce the energetic and economic efficiency of producing milk. Thus, the challenge is to identify ways to feed less protein while maintaining or enhancing milk production.

Up to 90% of administrated antibiotics are eliminated from the animal body through the faeces or urine, implying that manure generated from animal production represents a major route of antibiotic transfer to the environment. The presence of antibiotics, even at very low concentrations, can contribute to emergence of antibiotic resistance genes (ARG) and selection of antibiotic resistant bacteria.

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.

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.

In the study, the effects of homogenization conducted at higher pressure than the conventional (10 megapascal [MPa] for the first stage and 5 MPa for the second stage) on curd structure of set yogurt was investigated, the focus being on the fat globule size. Each yogurt mix was adjusted at the range of fat globule sizes from 0.45 μm to 1.1 μm by a homogenizer and then heated at 95°C for 5 minutes (conventional heat treatment), 120°C for 2 seconds (ESL processing) or 140°C for 2 seconds.