The Research Column

Discipline: calf rearing; Key words: colostrum storage, colostrum feeding, calf health, immunoglobulin G.

Discipline: dairy and health; Key words: bioactive peptides, cytotoxicity, mutagenicity, immunomodulatory function, side effects.

Discipline: nutrition/feeding; Key words: milk protein, proteomics, bioactive, low abundance protein. 

Discipline: calf rearing; Key words: calf, colostrum, colostrum replacer, passive transfer. 

Discipline: fermentation/digestion; Key words: rumen microbiota, feed efficiency, behavior, PCA

Due to perceived health reasons, consumers have shown an increasing interest in the consumption of cheese with a lower fat content. One of the main properties of reduced-fat cheeses is a higher protein to fat ratio that results in a more compact structure leading to a firmer and rubbery texture, a lack of flavour, bitterness (unacceptable sensory properties), development of off-flavours, poorer melting properties and a translucent appearance.

Greenhouse gases (GHG), including methane (CH4), play an important role in global warming. Methane has 28 times the global warming potential of CO2. Although in SA the figures are much lower due to the small size of the dairy industry, the global dairy supply chain produces 20% of the livestock-sector’s GHG, and 46.5% of that is from enteric CH4.

Improved animal health and resilience are important breeding objectives for the dairy cow. Many diseases affecting the cow occur in the first 30 days after calving. Some of these diseases are associated with metabolic disorders such as ketosis and milk fever, which can have deleterious effects on animal health and welfare and farm profitability. Although heritability estimates of metabolic disorders are generally low, sufficient genetic variation exists suggesting that improvement in metabolic health through selection should be possible.

Accurate and timely detection of pregnancy is vital in commercial milk production enterprises. There are several methods to do so including observation of non-return to oestrus, trans-rectal palpation, trans-rectal or trans-cutaneous ultrasonography, and analysis of progesterone and pregnancy-associated glycoproteins in milk or blood. However, these methods have an associated cost, are not all efficient and some require animal handling, which might limit their practical implementation.

Feed efficiency is usually expressed as the amount of milk produced per unit of feed intake. However, this definition is a ratio trait, which is challenging to incorporate in selection indices. Residual feed intake (RFI) is an alternative expression of feed efficiency. It is defined as the difference between observed and predicted dry matter intake (DMI).