Protein metabolism, body composition and oxygen consumption in young bulls divergent in residual feed intake offered two contrasting forage-based diets.

Protein metabolism and body composition have been identified as major determinants of residual feed intake (RFI) in beef cattle fed high-starch fattening diets. This study aimed to evaluate if these two identified RFI determinants in beef cattle are the same across two contrasting silage-based diets. During two consecutive years, an 84-day feed efficiency test (Test A) immediately followed by a second 112-day feed efficiency test (Test B) was carried out using a total of 100 animals offered either one of two diets (either corn silage- or grass silage-based) over 196 days.

Common and diet-specific metabolic pathways underlying residual feed intake in fattening Charolais yearling bulls.

Residual feed intake (RFI) is one of the preferred traits for feed efficiency animal breeding. However, RFI measurement is expensive and time-consuming and animal ranking may depend on the nature of the diets. We aimed to explore RFI plasma biomarkers and to unravel the underlying metabolic pathways in yearling bulls fed either a corn-silage diet rich in starch (corn diet) or a grass-silage diet rich in fiber (grass diet).

Contribution of nutrient fluxes to the evolution of the net energy systems, example of the INRA feeding system for beef cattle.

Energy feeding systems define energy as a whole, but progress made to define metabolizable energy (ME) as the sum of the metabolizable nutrients produced by digestion and available for tissue metabolism in a wide range of nutritional situations opens the way to quantitatively model and predict nutrient fluxes between and within tissues and organs and improve predictions of energy use. This review addresses the contribution of nutrient flux concepts and data to the evolution of the Institut de la Recherche Agronomique (INRA) energy feeding system for growing and fattening cattle and evaluates the outcomes on the net energy (NE) requirements. It summarizes recent progress made to quantitatively predict nutrient fluxes both at digestive and visceral levels.

The origin of N isotopic discrimination and its relationship with feed efficiency in fattening yearling bulls is diet-dependent.

Nitrogen (N) isotopic discrimination (i.e. the difference in natural 15N abundance between the animal proteins and the diet; Δ15N) is known to correlate with N use efficiency (NUE) and feed conversion efficiency (FCE) in ruminants.

Natural 15N abundance in specific amino acids indicates associations between transamination rates and residual feed intake in beef cattle.

Improving the ability of animals to convert feed resources into food for humans is needed for more sustainable livestock systems. Genetic selection for animals eating less while maintaining their performance (i.e.

Exploration of Biological Markers of Feed Efficiency in Young Bulls.

The efficiency with which ruminants convert feed to desirable products is difficult to measure under normal commercial settings. We explored the use of potential biological markers from easily obtainable samples, that is, blood, hair, and feces, to characterize potential causes of divergent efficiency when considered as residual feed intake (RFI) or feed conversion efficiency (FCE). A total of 54 Charolais bulls, 20 in period 1 and 34 in period 2, were examined for individual dry matter intake (DMI) and growth.

Natural (15)N Abundance in Key Amino Acids from Lamb Muscle: Exploring a New Horizon in Diet Authentication and Assessment of Feed Efficiency in Ruminants.

Natural (15)N abundance (δ(15)N) varies between individual amino acids (AAs). We hypothesized that δ(15)N of nontransaminating and essential AAs ("source" AAs, such as phenylalanine) present in animal tissues could be used as a marker of dietary origin, whereas δ(15)N of transaminating AAs ("trophic" AAs, such as glutamic acid) could give more detailed insights into animal feed efficiency. Two diets based on dehydrated Lucerne pellets were tested in growing lambs, which promoted different feed efficiencies.

Conception and development of a bibliographic database of blood nutrient fluxes across organs and tissues in ruminants: data gathering and management prior to meta-analysis.

In the organism, nutrient exchanges among tissues and organs are subject to numerous sources of physiological or nutritional variation, and the contribution of individual factors needs to be quantified before establishing general response laws. To achieve this, meta-analysis of data from publications is a useful tool. The objective of this work was to develop a bibliographic database of nutrient fluxes across organs and tissues of ruminant animals (Flora) under Access using the Merise method.

Influence of maturation and cooking treatments on the nutritional value of bovine meats: Water losses and vitamin B12.

The aim of the study was to determine the influence of maturation and of cooking processes on water losses and on the vitamin B12 content of meat. Three types of muscle (Longissimus lumborum, Longissimus thoracis and Triceps brachii) were sampled from a total of 16 animals, representative of animals raised for meat production in France. Three durations of maturation were compared: 1, 3 and 14 days.

Nutritional value of meat: the influence of nutrition and physical activity on vitamin B12 concentrations in ruminant tissues.

An important nutritional characteristic of ruminant meat is its high content in vitamin B12. The variability of these contents is not known. Three studies were been set up in order to test the influence of the animal species (2 studies on Charolais steers slaughtered at 30-32 months of age, n = 24 and n = 30 and a third one on lambs slaughtered at 4.

Whole body glucose turnover in growing and non-productive adult ruminants: meta-analysis and review.

The objectives of the present paper were to review and quantitatively determine the influence of the nutritional factors on whole body glucose turnover in growing and adult non-productive ruminants. A meta-analysis approach was used. The dietary grain: forage ratio significantly increased the slope of the relationship between glucose turnover and metabolisable energy intake.

Propionate supplementation did not increase whole body glucose turnover in growing lambs fed rye grass.

The objective of the present study was to investigate the effects of propionate supplementation on whole body glucose turnover in growing lambs fed frozen rye-grass at 1.5 x maintenance using [1-13C]-glucose. Intraruminal infusion of propionate (0.

Effects of intraruminal propionate supplementation on nitrogen utilisation by the portal-drained viscera, the liver and the hindlimb in lambs fed frozen rye grass.

The influence of propionate supplementation on the splanchnic metabolism of amino acids (AA) and other N compounds (urea-N and NH3-N) and the supply of AA and NH3-N to the hindlimb was investigated in growing lambs. Six rumen-cannulated and multicatheterised lambs (32.2 kg) were fed frozen rye grass at 690 kJ metabolisable energy intake/d per kg average metabolic body weight.

The incorporation of solubilized wheat proteins in milk replacers for veal calves: effects on growth performance and muscle oxidative capacity.

Replacement of skim milk proteins by solubilized wheat protein (SWP) in milk replacers for veal calves would contribute to the reduction in feeding costs. The occurrence of metabolic disorders has, however, been reported. Forty-two male calves received one of three treatments over 140 days: a control diet, a diet containing SWP without or with branched-chain amino acid supplementation.

Intraruminal propionate supplementation modifies hindlimb energy metabolism without changing the splanchnic release of glucose in growing lambs.

The influence of propionate supplementation on the splanchnic metabolism of energy-yielding nutrients and the supply of glucose to the hindlimb was investigated in growing lambs. Six rumen-cannulated and multicatheterized lambs (32.2 kg), fed frozen rye grass at 690 kJ metabolizable energy intake/d per kg body weight0.