| The production of high-quality milk is a prerequisite for sustaining a profitable dairy industry. The number of somatic cells (macrophages, polymorphonuclear neutrophils, lymphocytes and epithelial cells) per mL of milk, usually called somatic cell count (SCC) is routinely used to identify subclinical mastitis and define quality standards. Elevated SCCs are associated with changes in milk composition, resulting in poor quality of milk and milk products. SCC in milk is influenced by many factors, such as animal species, milk production level, lactation stage and also the individual and environmental factors besides management practices. A threshold of <200,000 cells/mL is considered to be of the most practical value for determining the health of mammary quarter. This review aims to highlight the importance of somatic cells for improving udder health and quality of milk as well as milk products.

The presented study aimed at investigating the residual feed intake (RFI) of Sahiwal calves, nutrient utilisation as affected by RFI and its relationship with methane (CH4) emissions and some blood metabolites. Eighteen male Sahiwal calves (10-18 months of age; mean body weight 133 kg) were fed ad libitum with a total mixed ration. After calculating RFI for individual calves (-0.40 to +0.34 kg DM/d), they were divided into three groups with low, medium and high RFI, respectively. Dry matter intake (DMI) was higher (p < 0.05) in Group High RFI, whereas digestibility of all nutrients except crude protein and ether extract was significantly higher in Group Low RFI. Nitrogen balance was also significantly higher in Group Low RFI (20.2 g/d) than in Group High RFI (17.0 g/d). Average daily gain and feed conversion ratio were similar among the groups. With exception of glucose, concentrations of all measured blood metabolites were higher in Group High RFI (p < 0.05). Compared with Group High RFI, the CH4 emission of Group Low RFI was significantly lower (on the basis g/d and g/kg DMI by 11% and 19%, respectively). Furthermore, the CH4 emission [g/d] was significantly correlated with RFI (r = 0.77). Because higher feed efficiency and less CH4 production were observed in Group Low RFI, it was concluded that RFI can be used as a measure of feed efficiency, which has a potential to select Sahiwal calves for lowered CH4 emissions.

Crop residues are often referred to as 'lignocellulosics' as they are rich in cellulose which is bound with a biopolymer lignin. Rumen microbiota (bacteria, protozoa and fungi), even with their hydrolytic enzymes, are not very competent enough to break these bonds efficiently. Biological treatment of such crop residues using white rot fungi (WRF) can break the ligno-cellulose complexes, liberating free cellulose and thus enhancing their feeding value for ruminants. Biologically treated roughages have higher digestibility for most of the nutrients (both cell walls and cell solubles) with an increase in crude protein content as compared to untreated material, besides ensuring more fermentable substrates in the rumen. Further, recent studies have indicated low methane emission from feedstuffs subjected to solid state fermentation (SSF) with ligninolytic fungi as a result of their improved digestion and nutrient assimilation. This review primarily deals with the nature and composition of crop residues, their inherent nutritive constraints as ruminant feed and to overcome the same by means of biological treatments. The progresses to date in in vitro and in vivo studies on biologically treated lignocellulosics have also been reviewed.

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