Annales De Zootechnie 

About: Annales De Zootechnie is an academic journal. The journal publishes majorly in the area(s): Rumen & Grazing. Over the lifetime, 2011 publications have been published receiving 18344 citations.

Methane production by ruminants: its contribution to global warming

Abstract: The aim of this paper is to review the role of methane in the global warming scenario and to examine the contribution to atmospheric methane made by enteric fermentation, mainly by ruminants. Agricultural emissions of methane in the EU-15 have recently been estimated at 10.2 million tonnes per year and represent the greatest source. Of these, approximately two-thirds come from enteric fermentation and one-third from livestock manure. Fermentation of feeds in the rumen is the largest source of methane from enteric fermentation and this paper considers in detail the reasons for, and the consequences of, the fact that the molar percentage of the different volatile fatty acids produced during fermentation influences the production of methane in the rumen. Acetate and butyrate promote methane production while propionate formation can be considered as a competitive pathway for hydrogen use in the rumen. The many alternative approaches to reducing methane are considered, both in terms of reduction per animal and reduction per unit of animal product. It was concluded that the most promising areas for future research for reducing methanogenesis are the development of new products/delivery systems for anti-methanogenic compounds or alternative electron acceptors in the rumen and reduction in protozoal numbers in the rumen. It is also stressed that the reason ruminants are so important to mankind is that much of the world's biomass is rich in fibre. They can convert this into high quality protein sources (i.e. meat and milk) for human consumption and this will need to be balanced against the concomitant production of methane.

Ruminant milk fat plasticity: nutritional control of saturated, polyunsaturated, trans and conjugated fatty acids

Abstract: After a brief survey of metabolic pathways and nutrient fluxes involved in mammary lipogenesis, this review summarises the known effects of diet on ruminant milk fat composition. Special attention is given to fatty acids that could play a positive role for human health, such as butyric acid, oleic acid, C18 to C22 polyunsaturated fatty acids and conjugated linoleic acid (CLA). The efficiency of the transfer of C18:2, C18:3, C20:5, C22:5 and C22:6, from the duodenum to the milk, is reviewed. The main dietary factors taken into account are the nature of forages, including pasture, and the supplementation of dairy rations with protected or unprotected vegetable or fish oils. Dose-response curves of milk CLA are reviewed for different fat supplements, as well as the non-linear relationship between milk CLA and trans C18:1. The potential of dietary factors to increase the mean CLA content in cow milk fat is about 300% above basal values. There is, however, a need to evaluate how the different feeding strategies could change the other aspects of milk fat quality.

Dietary fatty acids and human health

Abstract: A considerable amount of evidence has accumulated to support the view that the very long chain omega 3 fatty acids (eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)) have beneficial cardiovascular and anti-inflammatory properties and that levels of their consumption are insufficient in most Western diets. More recently, attention has been given to the possibility that the precursor omega-3 PUFA, alpha linolenic acid (ALNA), may share some of the beneficial actions of EPA/DHA on human health. Further research into the metabolism and physiological actions of ALNA, and comparisons with EPA/DHA, is needed before conclusions regarding the optimal amounts and types of omega-3 PUFA for human health can be defined. Conjugated linoleic acid (CLA), which arises as a metabolic by-product of rumen hydrogenation and which is found in foods of animal origin, has been proposed to possess potent health promoting properties, but much of this research has been conducted in experimental animals. There is an urgent need for complementary studies in human volunteers, to confirm the putative anti-carcinogenic, anti-atherogenic, anti-lipogenic and immuno-suppressive properties of CLA.

The effect of daily herbage allowance, herbage mass and animal factors upon herbage intake by grazing dairy cows

Abstract: L'effet de la quantite d'herbe allouee (DHA = biomasse (HM) x surface offerte journellement (DOA)) et des caracteristiques des animaux sur les quantites de MO d'herbe ingerees au pâturage (HOMI) ont ete analysees au cours de deux essais. Dans l'essai 1, deux niveaux de DHA (Bas et Moyen, 19 et 26 kg MO/vache/jour) ont ete compares dans un schema en continu en utilisant deux groupes de cinq vaches appariees. Dans le second essai, trois niveaux d'herbe allouee (Bas, Moyen et Haut ; 19, 29 et 46 kg/jour) ont ete compares dans un schema en carre latin 3 x 3 en utilisant trois lots de cinq vaches. Tous les animaux etaient en milieu de lactation et six primipares ont ete utilisees par essai. A la mise a l'herbe, la production de lait a 4 % (FCMt) et le poids vif (LW) variaient de 17 a 35 kg/jour et de 510 a 680 kg. Les vaches n'ont pas recu de concentre et ont ete conduites en pâturage rationne sur prairies de ray-grass anglais pendant toute la duree des essais. La biomasse coupee au niveau du sol a varie de 3,5 a 7,1 t MO/ha entre les periodes. Dans l'essai 1, HOMI (13,5 versus 14,9 kg/j) et la production de lait 4 % (20,6 versus 22,0 kg/jour) ont eu tendance a augmenter entre le traitement Bas et Moyen mais les differences n'ont pas ete significatives. Dans l'essai 2, HOMI a augmente de maniere curvilineaire (13,8 ; 16,2 ; 16,7 kg/jour) et la production de lait 4 % a augmente lineairement avec le niveau d'herbe allouee (20,4 ; 21,7 et 23,0 kg/jour). HOMI a toujours ete beaucoup plus faible pour les vaches primipares que les vaches adultes et des differences interindividuelles importantes sont apparues pour un meme rang de lactation. A partir de l'ensemble des donnees individuelles nous avons montre que HOMI peut etre predite a partir de DHA et des caracteristiques des animaux : HOMI = 7,9 - 98 DHA -1 + 0,264 FCMt + 0,0073 LW (n = 95, R 2 = 0,60, etr = 1,77 kg). Cependant, la precision de ce modele est sensiblement amelioree lorsque l'on considere separement les deux composantes de DHA : HOMI = -20,4 - 115 DCA -1 + 9,63 HM - 0,873 HM 2 + 0,266 FCMt + 0,0095 LW (R 2 = 0,70, etr = 1,56 kg). Ces relations montrent que HOMI est affectee par DHA mais aussi que la biomasse et/ou la structure initiale de la prairie affecte egalement les quantites ingerees. De plus les quantites ingerees augmentent avec le potentiel de production des animaux et cet accroissement couvre environ les deux tiers des besoins supplementaires de production pour des pâturages de bonne qualite.

Probiotics for ruminants

Abstract: The digestive anatomy and physiology of ruminants is markedly different to that of non-ruminant animals, including pigs and man. The ruminant has two additional digestive organs at the anterior end of the tract. The first of these, the rumen, contains in the dairy cow, for example, a liquid volume of 60–100 litres. This organ is essentially a fermentation chamber, containing about 1010 bacteria and 105–106 ciliate protozoa ml-1, together with an unknown, probably smalI, number of anaerobic fungi. The partly fermented food and the microorganisms then pass through the omasum, which is much smaller than the rumen (Figure 12.1). Its function is primarily to absorb both water and soluble nutrients.