Foraging Behaviour and Intake in Temperate Cultivated Grasslands

In temperate areas, grazing provides a large part of the nutrient requirements of ruminants and may be an important form of land use. In Europe, grassland occupies some 150 million hectares, and grazing provides about 60 to 75% of the nutrient requirements of cattle (Wilkins and Vidrih 2000). From the end of the 80’s, agricultural surpluses in Europe have led to production quotas and increased interest in more extensive systems. At the beginning of the 90’s, the emergence of the notion of sustainable agriculture combining economic, social (concerns in dereliction of less-favoured rural areas), and environmental issues (pollution, loss of biodiversity arising from intensification, environmental degradation…) strengthened the emphasis on livestock farming systems based on grazing. The challenge is to develop grazing systems that contribute to the economic sustainability of agriculture, that able to ensure the preservation of the rural landscape, with minimum recourse to non-renewable resources, while preserving and/or improving the environment. Grazing systems are further favoured by the ‘green’ image of their products, grassland-based food production being considered as safe, ‘natural’ and respectful towards animal welfare. Recent findings demonstrated the nutritional advantages of grassland-based food products (Demeyer and Doreau 1999), and the possibility of traceing grass-feeding in animal products by the use of biomarkers (Prache and Theriez 1999). In the milk production systems of Europe, milk quotas have increased the pressure on production costs so emphasizing the interest in increasing the animals’ voluntary intake from grazed swards. Environmental concerns have questioned N fertilisation and cattle waste management. Both renewed interest in increasing the use of legumes in swards. In grasslands areas that are devoted to beef cattle and sheep, systems are generally more extensive; farmers have to manage larger flocks on larger and more diversified areas, and to conciliate production with environmental objectives (maintaining open landscapes, contributing to landscape biodiversity)

Comparaison des qualités sensorielles de la viande et de la carcasse d’agneaux élevés au pâturage en production biologique ou conventionnelle à deux niveaux de disponibilités en herbe

Nous avons comparé les qualités sensorielles des carcasses et des viandes d’agneaux engraissés au pâturage en élevage biologique ou conventionnel (O vs. C) à deux niveaux de disponibilités en herbe (Haut H vs. Bas L). Le profil de croissance a été maintenu similaire entre les deux systèmes de production. L’expérimentation a été conduite pendant deux années avec 12 agneaux mâles castrés de race Limousine dans chaque groupe OH, OL, CH et CL chaque année. Les traitements O et C différaient par le niveau de fertilisation azotée minérale épandu sur les parcelles. Les parcelles expérimentales étaient des repousses après fauche et elles étaient conduites en pâturage tournant pour conduire à un âge moyen des agneaux à l’abattage de 5 et 6 mois dans les lots H et L respectivement. Les côtelettes O ont été moins appréciées que les côtelettes C. L’indice de rouge du muscle longissimus thoracis et lumborum après 2h d’exposition à l’air a été plus élevé chez les agneaux L que chez les agneaux H, indiquant les effets possibles d’une intensification de l’élevage biologique à travers une augmentation du chargement

Un mode de conduite biologique et un niveau élevé d'herbe améliorent la qualité nutritionelle des acides gras de la viande chez l'agneau engraisse au pâturage

This study aimed at comparing the nutritional quality of meat fatty acids (FA) of pasture-fed lambs reared organically or conventionally and offered two levels of herbage availability. Forty eight castrated male lambs of Limousine breed were used in a 2 x 2 experimental design, i.e. production system (Organic –O- vs. Conventional –C-) x level of herbage availability (High vs. Low). The O and C pastures differed in the level of on-pasture mineral N fertilization (0 vs. 100 U. ha-1. year-1) since 10 years. The level of pasture availability was managed to obtain a mean lamb age at slaughter of 5 vs. 6 months in the High and the Low level respectively. GLC analysis of fatty acids from the Longissimus thoracis muscle showed that organic farming system improved the health value of lamb meat by decreasing the level of saturated FA and especially 16:0, thus leading to a higher value of polyunsaturated FA (PUFA) to saturated FA ratio (+15%, P<0.03) and increasing the level of CLA (+18.2%, P< 0.002). The high level of herbage availability led to a better nutritional and health value of meat FA by increasing significantly deposition of n-6 PUFA (+16.3%), n-3 PUFA (+15%) and CLA (+20.2%) in LT muscle to the detriment of saturated FA (-3.4%). In conclusion, the present study confirmed the general interest of pasture-feeding on the nutritional quality of the lamb meat. It showed, for the first time, the beneficial impact of organic farming on the health value of lamb meat FA by favouring deposition of PUFA (compared to saturated FA) and CLA, this effect being reinforced by a high level of pasture availability

Elasticity of Ingestive Behaviour and Intake in Sheep Associated with Food Diversity on Plurispecific Swards

Animals on heterogeneous swards generally opt for a varied diet. This may stimulate their intake, unless searching constraints limit intake rate (Champion et al., 1998). However the management of plurispecific swards presents a risk of overgrazing the preferred species and undergrazing the less-preferred species. This study aimed to test the effect of type of diversity and type of management on the elasticity of ingestive behaviour and intake in sheep

Qualités de la viande d’agneaux d’herbe produits en élevage biologique ou conventionnel

La mention "Agriculture Biologique" sur un produit garantit une manière de produire, mais l’obligation de résultats est limitée à la conformation et l’état d’engraissement de la carcasse, d’où des questions sur les qualités alimentaires du produit viande

Comparison of the meat and carcass quality of lambs raised in organic or conventional production systems.

The ‘organic’ label on a product guarantees that synthetic fertilisers, pesticides and hormones are not used in the production process and that the use of pharmaceutical products and drugs is limited. However, product quality is often questioned and we have to anticipate the consumer demand for product quality guarantees. This study was conducted to compare the sensory and nutritional meat and carcass qualities of lambs raised under an organic (O) or a conventional (C) production system. Comparisons were made with both pasture-fed lambs and lambs that were stall-fed indoors with concentrate and hay. The experiment was conducted over two years for stall-fed lambs (S) (group O, n=24; group C, n=24) and three years for pasture-fed lambs (P) (group O, n=36; group C, n=36). For P lambs, O and C production systems differed in terms of the level of mineral N fertilisation of the pasture. For S lambs, the feed was organic vs. conventional, and the ingredients of O and C concentrates were the same. The nutritional quality of the meat (longissimus dorsi) was assessed in terms of its fatty acid (FA) composition, and the sensory quality of the loin chop was assessed by a trained sensory panel. In stall-fed lambs, the health value of meat FA for human consumption was higher in the O group than in the C group, but there was no difference in the sensory quality of the meat and the carcass between the O and C groups. In pasture-fed lambs, there were no significant differences between the O and C groups in terms of the health value of meat FA. However, in pasture-fed lambs, the loin chops had a higher level of abnormal odour of the fat in the organic than in the conventional group, probably due to a higher proportion of white clover in the diet

Carcass characteristics and beef quality of young grass-fed Angus x Salers bovines

To characterize carcass and meat attributes, such as beef eating quality in specific farming conditions, 31 young grass-fed crossbred Angus x Salers cattle in two farming systems (a mono-cattle system versus a mixed system with beef cattle and sheep) were used in this study. Three muscle cuts (striploin—m. longissimus dorsi et thoracis; bolar blade—m. triceps brachii caput longum; internal flank plate—m. obliquus internus abdominis) were used for consumer eating quality testing and striploin was used for panelist eating quality assessment, and objective measurements [Warner–Bratzler shear force (WBSF) and fatty acid (FA) and antioxidant contents]. Results indicated that the farming system had no impact on carcass characteristics or meat quality, but it tended to affect FA content, which is likely explained by between-system differences in animal maturity (assessed by ossification score). Animal gender had significant effects on three eating quality traits evaluated by untrained consumers, with higher flavor liking, overall liking, and overall meat eating quality (MQ4) scores in females than in males. Additionally, FA contents were correlated with sensory quality traits to varying extents: consumer-scored tenderness, flavor, and overall liking were mainly positively correlated with ω-3 and ω-6 polyunsaturated fatty acid (PUFA) contents, and panelist-evaluated tenderness and abnormal flavor were more positively correlated with total lipids, saturated fatty acid (SFA), and monounsaturated fatty acid (MUFA) contents. Overall, this study showed that specific grass-fed crossbred Angus x Salers cattle can produce lean meat rich in ω-3 PUFAs with a low ω-6/ω-3 ratio and with “better than average” beef eating quality

Dietary experience modifies horses' feeding behavior and selection patterns of three macronutrient rich diets

Choice feeding is often used to investigate an animal’s nutritional requirements and dietary preferences. A problem with this approach is that animals with long gut transit times, such as the horse, may find it difficult to associate a chosen food with its nutritional consequence when alternative foods are presented simultaneously. One solution is to present foods singly for a period of time before a simultaneous choice session to allow the development of learned associations. This method was used to determine if horse’s voluntary intake and feeding behavior was influenced by the macronutrient composition of the diet. Seven stabled horses, maintained on a low intensity exercise regimen, were allowed, on an ad libitum basis, haylage and 3 isocaloric forage based diets that were rich in 1 of 3 macronutrients (protein, lipid, and hydrolyzable carbohydrate). Initially, diets were presented as a 3-way choice for 5 d (self-selection a [SSa]), then singly (monadic phase) with exposure to each diet for 2 separate periods of 3 d each, and finally again as a choice for 5 d (self-selection b [SSb]). The total amount of trial diet offered differed with trial phase, with 2 to 2.5% of BW during SSa and the monadic phase, increasing to ad libitum access during SSb. To control differences in the total amount of trial diet offered, 2 measurements of voluntary intake were taken at 4 and 22 h postpresentation. Daily macronutrient and energy intakes were estimated from proximate analysis of the trial diets and batches of haylage fed. Feeding behavior was observed over a single 4-h period during both self-selection phases. Horses showed no initial preference after 4 h for any 1 diet during SSa. Following the monadic phase, horses demonstrated a preference for the protein and hydrolyzable carbohydrate rich diets over the lipid rich diet (P < 0.001). Dietary experience modified foraging behavior as the total number of visits to the diets decreased during SSb (P < 0.005). Analysis of 24 -h macronutrient consumption showed that protein and hydrolyzable carbohydrate intake increased during SSb, whereas lipid intake remained constant over both self-selection phases (P < 0.001). These data indicate for perhaps the first time that horses can respond to dietary macronutrient content and that single presentations during choice studies facilitates expression of dietary preferences