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Grazing plays an important role in milk production in most regions of the world. In this review, some challenges to the grazing cow are discussed together with opportunities for future improvement. We focus on daily feed intake, efficiency of pasture utilization, output of milk per head, environmental impact of grazing and the nutritional quality to humans of milk produced from dairy cows in contrasting production systems. Challenges are discussed in the context of a trend towards increased size of individual herds and include limited and variable levels of daily herbage consumption, lower levels of milk output per cow, excessive excretion of nitrogenous compounds and requirements for minimal periods of grazing regardless of production system. A major challenge is to engage more farmers in making appropriate adjustments to their grazing management. In relation to product quality, the main challenge is to demonstrate enhanced nutritional/processing benefits of milk from grazed cows. Opportunities include more accurate diet formulations, supplementation of grazed pasture to match macro‐ and micronutrient supply with animal requirement and plant breeding. The application of robotics and artificial intelligence to pasture management will assist in matching daily supply to animal requirement. Wider consumer recognition of the perceived enhanced nutritional value of milk from grazed cows, together with greater appreciation of the animal health, welfare and behavioural benefits of grazing should contribute to the future sustainability of demand for milk from dairy cows on pasture. [ABSTRACT FROM AUTHOR]

The case for grazing dairy cows at pasture is reviewed in six categories: (i) optimal land use for food production; (ii) soil carbon sequestration; (iii) carbon footprint; (iv) animal health and welfare; (v) effects on human health of milk produced from grazed pasture; and (vi) consumer demand for milk from grazed cows. Land best-suited to grazing is uncultivatable peaty soil receiving relatively low levels of fertilisation. With soil carbon sequestration, carbon footprint is lower for grazing than for other systems of milk production. Some indices of animal health and welfare (e.g., lameness, status of hock integument) are influenced positively by extent of grazing. Benefits to human health may accrue from higher levels of essential amino acids, carotenoids, omega-3 fatty acids and conjugated linoleic acid in milk from cows given pasture compared to diets based on silage and concentrates. Milk producers, processors and supermarkets are responding to consumer demand for milk and milk products from cows given access to pasture during the grazing season. The major constraint to milk production from grazing is energy intake. Research opportunities to address this constraint include application of remote sensing and artificial intelligence to grazing management. [ABSTRACT FROM AUTHOR]

Troponin C has been isolated from rabbit slow skeletal and cardiac muscle and the complete amino acid sequence of the slow muscle protein determined. Amino acid analysis and peptide mapping of the cardiac protein showed it to be very similar to, if not identical with, the slow muscle protein. This identity has been proved by the isolation and characterisation of tryptic peptides from the cardiac protein. It seems very likely that troponin C from these two tissues is the product of a single gene, in contrast to troponin I and troponin T which are the products of different genes. The amino acid sequence shows only one difference from that of bovine cardiac troponin C, the highly conservative replacement of an aspartic for a glutamic acid at position 115. No differences were found in the N-terminal region where these proteins appear to have lost one of the Ca2+ binding sites found in fast skeletal muscle troponin C. The possible significance of this finding in relation to the binding of troponin C to the different types of troponin I is discussed. [ABSTRACT FROM AUTHOR]

The amino acid sequence of troponin I from chicken breast and leg muscle has been determined using tryptic and CNBr peptides. The protein contains 182 residues and has a molecular weight of 21136. The N-terminus is blocked and is probably acetylated. 35 of the residues have acidic and 45 have basic side chains giving an overall net positive charge of 9. The CNBr peptides from both breast and leg troponin I have been shown to be identical and no heterogeneity has been found in the tryptic peptides isolated from a mixture of the two proteins. It may thus be taken that the two proteins are identical. Comparison with the sequence of troponin I from rabbit fast skeletal muscle shows strong homology with 34 differences out of 182 residues. The major difference is in a deletion of three residues, from 152 to 154, in the rabbit protein. [ABSTRACT FROM AUTHOR]

Grassland accounts for a high proportion of the agricultural area of the United Kingdom, but the significance of its contribution to the nation's food supply has been questioned. Using representative figures for the composition of UK ruminant livestock diets, we estimated the total production of human-edible protein from grass and forage crops consumed by cattle and sheep. We found that this equates to 21.5 g of protein per person per day, of which 15.2 g comes from milk, 4.71 g from beef and 1.60 g from sheep meat. This represents 45% of the total amount of human-edible animal protein produced in the UK (46.6 g/head) and is equivalent to one-third of the recommended adult human daily protein intake of 64 g/head. Given the growing pressure to produce food in a more resource-efficient manner, grasslands have a valuable role to play in providing food alongside multiple public goods. [ABSTRACT FROM AUTHOR]

Two monoclonal antibodies, T1/7 and T1/61, have been prepared which are specific for chicken fast muscle troponin T. Both are of the IgGλ1 subclass. Both antibodies cross-react strongly with human fast and chicken cardiac troponin T, but while T1/7 reacts weakly with rabbit fast troponin T, T1/61 does not. The antibodies can be used for fibre typing of both chicken and human muscle. The antibodies have been used to identify fast troponin T on two-dimensional maps of proteins from a variety of chicken muscles by electrophoretic transfer to nitrocellulose followed by immunoperoxidase staining. Using this technique live variant forms of fast troponin T, have been identified. Two variants, fBT1 and fBT2, are expressed in breast muscle, while the other three, fLT1, fLT2 and fLT3 are expressed in leg muscle. Of the leg muscle variants, fLT1 and fLT2 correspond to the two forms described previously [Wilkinson, J. M., Moir, A. J. G. and Waterfield, M. D. (1984) Eur. J. Biochem. 143, 47 - 56]. The third variant, fLT3, has not been described before and is expressed in muscles which have a high content of slow fibres. In addition to these clearly defined variant forms immunostaining reveals multiple minor variants of troponin T present in leg muscle which may reflect complex RNA processing of the troponin T gene transcript. [ABSTRACT FROM AUTHOR]