Palatability in sheep and in vitro nutritional value of dried and ensiled sainfoin (Onobrychis viciifolia) birdsfoot trefoil (Lotus corniculatus), and chicory (Cichorium intybus).

Three temperate forages, sainfoin, birdsfoot trefoil, and chicory, characterized by elevated contents of plant secondary compounds, were compared to a ryegrass-clover mixture (control) in dried (Experiment 1) and ensiled form (Experiment 2) in their palatability and nutritional value. Palatability was measured in adult wethers (n = 6) allowed to choose between the familiar control forage and one of the three test plants. Palatability index was calculated from differences in intake of control and test plants measured after given times. Generally at first contact, palatability of the unfamiliar plants was low. Lag time until palatability index approached or exceeded a value of 100 was 2-5 d, but could not be related to the content of condensed tannins. Sainfoin had a high palatability, the highest content of condensed tannins (77.4 +/- 10.23 g/kg DM), a high content of duodenally utilisable crude protein (94.7 +/- 16.87 g/100 g CP), and a high content of metabolizable energy (9.5 +/- 0.38 MJ ME/kg DM), making this plant most promising for various purposes including anthelmintic action.

Effect of feeding dehydrated and ensiled tanniferous sainfoin (Onobrychis viciifolia) on nitrogen and mineral digestion and metabolism of lambs.

The effects of tanniferous sainfoin on digestion and metabolism have been investigated in 12 lambs in an incomplete cross-over design (n = 6). Effects of condensed tannins (CT) were evaluated by comparing dehydrated and ensiled sainfoin treated with and without polyethylene glycol (PEG). Dehydrated and ensiled grass-clover mixtures served as controls. The lambs were fed the treatment diets, including a mineral supplement, for 21 d. During the last 7 d excreta, rumen fluid and blood were sampled. The CT of sainfoin decreased rumen fluid ammonia concentration (p < 0.001) and increased the plasma concentration mainly of essential amino acids (p < 0.001). Body retention of phosphorus, calcium and magnesium was lower with sainfoin compared to PEG-treated sainfoin (p < 0.05). Sainfoin without PEG resulted in lower digestibilities of organic matter and neutral detergent fibre than sainfoin with PEG and the grass-clover mixture (p < 0.001). Ensiling of sainfoin led to the lowest N-retention. In conclusion, the reduction in ruminal ammonia and urine-N losses by sainfoin CT did not improve N-retention.

Digestive and metabolic utilization of lauric, myristic and stearic acid in cows, and associated effects on milk fat quality.

In an experiment with 3 x 6 Brown Swiss cows, the effects of dietary supplementations (40 g/kg) of non-esterified lauric (12 : 0), myristic (14 : 0) and stearic acid (18 : 0) on digestibility, metabolisability, milk fat composition and melting properties were investigated. The diet consisted of forage and concentrate in a ratio of 3 : 2. Cows were fed the C18 : 0 supplemented diet for 10 days before treatment feeding started for a 15-day experimental period where, at the end, excreta were quantitatively collected and gaseous exchange was measured. The DM intake averaged 17.9 kg/d for the C14 : 0 and C18 : 0 diets and was reduced (P < 0.05) by 18% in the C12 : 0 diet. The realised intakes of total C12 : 0, C14 :0 and C18 : 0 amounted to 368, 391 and 617 g/d in the respective groups. The efficiency of ME utilization for lactation was higher (P < 0.001) in the C12 : 0 group than in the two other groups indicating differences in metabolism of C12 : 0 in comparison with C14 : 0 and C18 : 0. Shifts in dietary fatty acid supplementation were clearly reflected in the milk fat composition. Associated changes were elevated CLA and C18 : 1 trans when supplementing C12 : 0, and a high C18 : 1 to C16 : 0 ratio (P < 0.05) in the C12 : 0and C18 : 0 groups which resulted in an easier melting milk fat than with supplementary C14 : 0. Despite certain favourable effects of C12 : 0 in metabolic energy utilization and milk fat melting properties (relative to C14 : 0), more research is needed on how to improve its palatability for dairy cows.

Methane emissions of differently fed dairy cows and corresponding methane and nitrogen emissions from their manure during storage.

This study investigated the effects of supplementing 40 g lauric acid (C12) kg(-1) dry matter (DM) in feed on methane emissions from early-lactating dairy cows and the associated effects on methane, nitrous oxide and ammonia release from the manure during storage. Stearic acid (C18), a fatty acid without assumed methane-suppressing potential in the digestive tract of ruminants, was added at 40 g kg(-1) DM to a control diet. The complete feed consisted of forage and concentrate in a ratio of 1.5:1 (DM basis). The manure was stored for 14 weeks either as complete slurry or, separately, as urine-rich slurry and farmyard manure representing two common storage systems. Methane release of the cows, as measured in respiratory chambers, was lower with C12 by about 20%, but this was mostly resulting from a reduced feed intake and, partly, from a lower rate of fibre digestion. As milk yield declined less than feed intake, methane emission per kg of milk was significantly lower with C12 (11.4 g) than with C18 (14.0 g). Faeces of C12-fed cows had a higher proportion of undigested fibre and accordingly methane release from their manure was higher compared with the manure obtained from the C18-fed cows. Overall, manure-derived methane accounted for 8.2% and 15.4% of total methane after 7 and 14 weeks of storage, respectively. The evolution of methane widely differed between manure types and dietary treatments, with a retarded onset of release in complete slurry particularly in the C12 treatment. Emissions of nitrous oxide were lower in the manures from the C12 treatment. This partially compensated for the higher methane release from the C12 manure with respect to the greenhouse gas potential. The total greenhouse gas potential (cow and manure together) accounted for 8.7 and 10.5 kg equivalents of CO2 cow(-1) d(-1) with C12 and C18, respectively. At unaffected urine-N proportion ammonia and total nitrogen losses from stored manure were lower with C12 than with C18 corresponding to the differences in feed and nitrogen intake. The present results suggest that manure storage significantly contributes to total methane emission from dairy husbandry, and that the identification of effective dietary mitigation strategies has to consider both the digestive tract of the animals and the corresponding manure.