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Review: Enhancing gastrointestinal health in dairy cows
- J. C. Plaizier, M. Danesh Mesgaran, H. Derakhshani, H. Golder, E. Khafipour, J. L. Kleen, I. Lean, J. Loor, G. Penner, Q. Zebeli
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Due to their high energy requirements, high-yielding dairy cows receive high-grain diets. This commonly jeopardises their gastrointestinal health by causing subacute ruminal acidosis (SARA) and hindgut acidosis. These disorders can disrupt nutrient utilisations, impair the functionalities of gastrointestinal microbiota, and reduce the absorptive and barrier capacities of gastrointestinal epithelia. They can also trigger inflammatory responses. The symptoms of SARA are not only due to a depressed rumen pH. Hence, the diagnosis of this disorder based solely on reticulo-rumen pH values is inaccurate. An accurate diagnosis requires a combination of clinical examinations of cows, including blood, milk, urine and faeces parameters, as well as analyses of herd management and feed quality, including the dietary contents of NDF, starch and physical effective NDF. Grain-induced SARA increases acidity and shifts availabilities of substrates for microorganisms in the reticulo-rumen and hindgut and can result in a dysbiotic microbiota that are characterised by low richness, diversity and functionality. Also, amylolytic microorganisms become more dominant at the expense of proteolytic and fibrolytic ones. Opportunistic microorganisms can take advantage of newly available niches, which, combined with reduced functionalities of epithelia, can contribute to an overall reduction in nutrient utilisation and increasing endotoxins and pathogens in digesta and faeces. The reduced barrier function of epithelia increases translocation of these endotoxins and other immunogenic compounds out of the digestive tract, which may be the cause of inflammations. This needs to be confirmed by determining the toxicity of these compounds. Cows differ in their susceptibility to poor gastrointestinal health, due to variations in genetics, feeding history, diet adaptation, gastrointestinal microbiota, metabolic adaptation, stress and infections. These differences may also offer opportunities for the management of gastrointestinal health. Strategies to prevent SARA include balancing the diet for physical effective fibre, non-fibre carbohydrates and starch, managing the different fractions of non-fibre carbohydrates, and consideration of the type and processing of grain and forage digestibility. Gastrointestinal health disorders due to high grain feeding may be attenuated by a variety of feed supplements and additives, including buffers, antibiotics, probiotics/direct fed microbials and yeast products. However, the efficacy of strategies to prevent these disorders must be improved. This requires a better understanding of the mechanisms through which these strategies affect the functionality of gastrointestinal microbiota and epithelia, and the immunity, inflammation and ‘gastrointestinal-health robustness’ of cows. More representative models to induce SARA are also needed.
Changes in crude protein fractions of forage legumes during the spring growth and summer regrowth period
- M. KRAWUTSCHKE, J. KLEEN, N. WEIHER, R. LOGES, F. TAUBE, M. GIERUS
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- The Journal of Agricultural Science / Volume 151 / Issue 1 / February 2013
- Published online by Cambridge University Press:
- 30 March 2012, pp. 72-90
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Only a few previous studies have analysed the crude protein (CP) fractions of the Cornell Net Carbohydrate and Protein System during the growth period of forage legumes. The objective of the present study was to investigate the changes in CP fractions during the spring growth and summer–autumn regrowth period of five forage legume species (alfalfa (also known as lucerne, Medicago sativa L.), birdsfoot trefoil (Lotus corniculatus L.), kura clover (Trifolium ambiguum M.B.), red clover (Trifolium pratense L.) and white clover (Trifolium repens L.)) grown in binary mixtures with perennial ryegrass (Lolium perenne L.) and also in pure stands (two red clover cultivars). Additionally, the specific polyphenol oxidase (PPO) activity was measured photometrically in the leaves of pure red clover swards. In both pure and mixed cropping, CP fraction A increased with advancing maturity, except for the legumes from mixed cropping in the summer–autumn growth period 2004 and 2005. The variation of CP fraction A was mostly positively related to the N yield and the amount of dinitrogen fixation. Although CP fraction A of pure red clover was negatively correlated with the specific PPO activity in the spring growth period, the specific PPO activity was less relevant for the variation of CP fraction A with respect to the whole growing season. CP fraction B generally made up the largest proportion of the CP. Pure red clover stands showed reducing amounts of CP fraction C during the growth period, whereas in legumes grown with ryegrass an increase was usually observed. Despite these differences, there was generally an increase of CP fraction C when the content of non-structural carbohydrates decreased. Red clover and birdsfoot trefoil herbage contained the highest proportions of CP fraction C in the CP, regardless of growth period and year. In conclusion, red clover and birdsfoot trefoil had a more favourable CP composition for ruminant nutrition compared to the other legume species, and in red clover this could not be clearly attributed to the specific PPO activity.
Agronomic performance and nutritive value of forage legumes in binary mixtures with perennial ryegrass under different defoliation systems
- J. KLEEN, F. TAUBE, M. GIERUS
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- The Journal of Agricultural Science / Volume 149 / Issue 1 / February 2011
- Published online by Cambridge University Press:
- 08 July 2010, pp. 73-84
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Protein in forage legumes is often poorly utilized by ruminants and high nitrogen (N) losses are expected. The objective of the present study was to investigate the effects of forage legumes (white clover, WC; red clover, RC; lucerne, LG; and birdsfoot trefoil, BT) in binary mixtures with perennial ryegrass (G) under different defoliation systems (silage, simulated grazing and grazing) on agronomic performance and forage quality. A high proportion of legumes may favour dry matter (DM) yield and the defoliation system may reduce the persistence of certain forage legumes, with a negative influence on the energy and N yield. Annual DM yield under grazing was highest for WC mixtures (WC+G, 1059·2 g DM/m²) compared to all other mixtures, confirming its adaptation to grazing. Mixtures with RC (RC+G) and LG (LG+G) performed similarly to WC+G, whereas BT mixtures (BT+G) were less competitive under more intensively used systems. Analyses of crude protein, cell wall characterization and protein fractionation showed a three-way interaction between year, mixture and defoliation system. RC and BT resulted in a positive protein quality of the mixtures, probably due to their content of secondary plant compounds. In conclusion, different forage legumes did not perform equally in the cutting and grazing systems, and both legume species and defoliation systems interacted in the production of forage of high protein quality for ruminant nutrition.