The benefits of pasture-based systems on the fatty acid composition of sheep meat appear to be achievable despite variability in the quality of the pastures. Lambs fed high levels of temperate pastures have an excess of N-ammonia derived from protein degradation. Furthermore, animal performance is highly variable depending on the quality of the pasture at the time of grazing, and high animal performance in these systems appears to be linked to the use of high-quality pastures with high availability, and is possibly added to by the inclusion of concentrates that allow increasing energy intake and a better use of the N in the pasture. The combination of high-quality pastures and total mixed ration offers a good alternative to the inclusion of concentrates in the diet, improving the use of N, and avoiding acidosis problems. However, information to determine the effect of a number of nutritional strategies on meat quality, and the minimum level of pasture intake necessary to achieve the benefits of pastoral systems is still lacking.

The nutritive value of cardoon (Cynara cardunculu.s L.) green forage (GF), dry leaves (DL) and straw (S) was studied from chemical composition analyses and from voluntary intake, digestibility and rumen degradability estimations obtained using adult wethers. Aptitude for being ensiled according to the wilting period was also evaluated making silages with fresh forage and after 24 and 94 hours of wilting. Green forage had a high nutritive value, as shown by low levels of fibre and lignin and its very high digestibility (86 % for OM). Nevertheless, its voluntary intake was relatively low (64 g DM.kg!' L W O .7 5), although very variable among animals. Fermentation characteristics of the GF silages were good and wilting reduced silage losses and improved the quality of silages. Nutritive value of DL was high, but limited only by a moderate crude protein content. Supplemented with urea, it had an OM digestibility similar to a medium-good quality hay (65.9 % average) and a voluntary intake equivalent to a good quality grass (75.9 g DM.kg!' LW(7 5). Finally, S was a typical fibrous and low protein forage, but when supplemented with urea, it had an intake and a digestibility higher than those of cereal straws. Variations in digestibility for OM and energy among the different non-preserved Cynara cardunculus forages showed close relationships with fibre fractions , especially with the acid detergent lignin content. " (© Elsevier / Inra). Cardoon / degradability / digestibility / intake / silage Résumé — Valeur nutritive du fourrage vert et des sous-produits de culture de Cynara car-dunculus. La valeur nutritive du fourrage vert, des feuilles sèches et de « la paille » de Cardon (Cynara cardunculus L.) a été étudiée à partir des analyses de composition chimique, et des estimations de digestibilité, de dégradabilité et d'ingestion volontaire chez le mouton. La valeur énergétique des

To establish the effects of access time to high-quality temperate fresh forage (FF) on intake and performance of cows fed a total mixed ration (TMR), 9 Holstein cows were assigned to three 3 × 3 Latin squares with 20-d periods with sampling in the last 10 d. The following treatments were evaluated: 0 (T0), 4 (T4), and 8 (T8) h of daily access to FF. Forage (Lolium multiflorum) was cut daily and offered ad libitum beginning at 0800 h in individual stalls, and a TMR was offered ad libitum during the period when cows had no access to FF. Fresh forage dry matter intake (DMI) increased and TMR DMI decreased with the access time to FF, whereas total DMI was 3.0 kg higher for T4 than for T8; no differences were detected with T0. Compared with T0, 8h/d of access to FF decreased milk, protein, and casein yields, and tended to decrease fat and lactose yields, but treatment had no effect on milk composition or feed efficiency. The milk fatty acid profile in T8 had a higher content of rumenic, vaccenic, and linolenic acids compared with T0. We concluded that cows with 4h of access to high-quality FF had similar DMI and milk yields as cows fed only the TMR, but more than 4h of access reduced DMI and performance without changes in feed efficiency, although milk fat had enhanced levels of beneficial fatty acids.

Changes in chemical nitrogen fractions and ruminal degradability of wilted and ensiled temperate forages were studied. Seven cultivated pastures from Uruguayan farms were sampled for their study in each of the following silage-making steps: fresh forage (F), wilted forage (W), and silage (S). Samples were analysed for crude protein (CP), soluble protein in buffer phosphate (SP), and neutral and acid detergent insoluble nitrogen (NDIN and ADIN). The degradability of dry matter (DM) and nitrogen (N) were measured in situ in three cows, and the effective degradability (ED) was calculated using outflow rumen rates of 3 and 6% per h (ED03 and ED06). Wilting reduced both ED06 of DM (F = 56.29%, W = 54.25%; P = 0.033) and N (F = 71.65%, W = 68.03%; P < 0.001). However, wilting did not produce significant changes in the chemical fractions. Forage fermentation produced an increase in SP (Average value of fresh and wilted forages (F + W) = 27.35%, S = 44.25% of CP; P < 0.001) and ADIN (F + W = 9.90%, S = 13.56% of CP; P = 0.014). Ensiling increased the soluble fraction (a) (F + W = 43.15%, S = 59.68%; P < 0.001), the undegradable fraction (u) (F + W = 16.52%, S = 18.45%; P = 0.007) and decreased the non-soluble degradable fraction (b) (F + W = 40.34%, S = 21.87%; P < 0.001) of N. Thus, fermentation produced significant changes in the chemical N fractions and ruminal degradability of DM and N in temperate regions, while wilting affected only the latter.

The aim of the experiment was to study diurnal variation in water‐soluble carbohydrate (WSC) concentrations in leaf and stem of tall fescue and lucerne in autumn and to determine the impact of these changes on the rate and the extent of in vitro fermentation. Vegetative herbage of lucerne and tall fescue were sampled at 0900, 1300 and 1700 h, following three consecutive regrowths between April and May. Whole plants, leaf and stem were analysed for chemical composition and in vitro gas production. There was a linear increase in WSC throughout the day for all plants and plant components ( P < 0.001). In both fescue and lucerne, this rise resulted in an increased rate of gas production, although this relationship was more pronounced in fescue. Use of time of day to govern grazing management decisions to potentially improve the rumen supply of WSC and nitrogen in autumn can be achieved from tall fescue or lucerne pastures.