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Individual methane emissions are a potential breeding goal for selection plans aimed at improving the sustainability of ruminant farming systems. However, a large-scale recording of individual methane emissions is hampered by the high costs of the equipment and the logistics of the experiments. Equations have been developed to predict methane emissions in dairy cattle based on variables such as dry matter intake (DMI), gross energy intake, body weight and milk fatty acids (FAs) profile. No equations are currently available for dairy sheep. The aims of this study were: (i) to estimate the enteric methane yield (eMY, expressed as g/kg of DMI) and enteric methane intensity (eMI, expressed as g/kg of FPCM) of dairy sheep using equations developed for dairy cattle that consider as predictors milk FA; (ii) to evaluate the effect of stage of lactation, parity and month of lambing on eMY and eMI; (iii) to estimate the heritability of eMY and eMI. For this purpose, 964 individual milk samples from Sarda dairy ewes were analysed for milk composition and FA profile. Nine different equations were used to predict eMY and eMI. Values of eMY ranged from 19.4 g/kg to 20.4 g/kg of DMI, whereas values of eMI ranged from 15.1 g/kg to 21.0 g/kg of DMI, respectively. Stage of lactation was an important factor in the variability of eMY (p <.01). Indeed, this trait increased towards the end of lactation. Both eMY and eMI were negatively correlated with milk yield, lactose concentration and urea and positively correlated with fat concentration and NaCl, respectively. Heritability of eMI and eMY estimated using a single trait model was 0.13 ± 0.05 and 0.05 ± 0.04, respectively. The values of heritability estimated for eMY using a bivariate models ranged from 0.10 to 0.16 and they were higher than the value estimated for eMI. Results of the present study, even if based on prediction equations developed for cows, increased the knowledge about the phenotypic and genetic background of methane emissions in Sarda dairy sheep. Methane emissions were predicted from fatty acids using equation developed for cows. Estimates were in agreement with the values reported in literature. Methane emissions were lowly heritable. [ABSTRACT FROM AUTHOR]

Context. Decreasing enteric methane emissions from small ruminants is important because methane is a greenhouse gas and a major contributor to global warming. Aim. The objective of this work was to test the effect of a dietary premix consisting of a blend of essential oils, bioflavonoids and chestnut tannins (EOP, essential oils and polyphenols) on methane emission from dry non-pregnant ewes. Methods. Twenty-four dry Sarda ewes were allocated to two homogenous groups: control and treatment groups. Both were fed with a total mixed ration, and the treatment group was supplemented with 1 g/day.ewe of EOP blend. Each animal followed a 20-day adaptation period before methane emission measurements. Methane emissions were measured using a ventilated hood system equipped with a digital gas analyser. Key results. The addition of a dietary EOP blend to the total mixed ration did not affect feed intake and nutrient digestibility. Ewes that received the EOP blend had a 13% lower methane yield than ewes that received the control diet (22.4 vs 25.5 g of CH4 per kg of dry matter intake; P < 0.05, respectively). The EOP blend had no impact on daily methane emission when calculated as g CH4/ewe or g CH4/kg bodyweight. Conclusions. The EOP blend at a daily dose of 1 g/day.ewe decreased methane yield under the experimental conditions described in this work. Implications. Feeding an EOP dietary blend to ewes can decrease methane emission. These results were obtained in vivo with typical farm conditions, suggesting that a similar response may occur in field conditions. [ABSTRACT FROM AUTHOR]

Grape seed is a by-product of the winery and distillery industry which could be used in animal nutrition. To test the hypothesis that dietary supplementation with this by-product can decrease the biohydrogenation (BH) of healthy fatty acids (FA), the present study evaluated the effects of grape seed supplementation, alone or combined with linseed, on ruminal BH processes in dairy sheep. In this 60-d trial, 24 lactating Sarda dairy ewes were assigned to four homogeneous groups and fed as follows: (1) control diet (CON), (2) a diet supplemented with 300 g/d per head of grape seed (GS), (3) a diet supplemented with 220 g/d per head of extruded linseed (LIN), (4) and a diet supplemented with a mix of both grape seed and linseed (300 and 220 g/d per head, respectively) (MIX). Ammonia, pH, volatile fatty acids (VFA) and FA composition were determined in rumen liquor at three sampling dates (20, 40 and 60 d). Rumen pH was not influenced by diet (P>0.05). The ammonia content was increased (P<0.05) in GS and MIX compared with LIN and CON. The molar proportions of acetate and propionate and their ratio were not affected by the diet (P>0.05), whereas the molar proportion of butyrate was the lowest in MIX. Rumenic acid (RA; CLA cis- 9, trans- 11) concentration increased in GS compared with CON (0.78 vs. 0.45 mg/100 mg FA; P<0.05), whereas the percentage of vaccenic acid (VA; C18:1 trans- 11) tended to increase (P<0.10) in GS compared with CON. The concentration of VA was higher in MIX than in CON (8.18 vs. 3.77 mg/100 mg FA; P<0.05), whereas RA did not differ between the same groups. The concentration of linoleic acid (LA; C18:2 n –6) decreased and stearic acid (SA; C18:0) increased in all supplemented groups, whereas linolenic acid (LNA; C18:3 n –3) decreased in the two groups receiving grape seed compared with CON and LIN. The concentration of total odd- and branched-chain fatty acids (OBCFA) decreased in all supplemented groups compared with CON (P<0.05), evidencing that grape seed and linseed supplementation influenced the ruminal BH processes. Grape seed was able to increase the accumulation of RA when supplemented alone, and of VA when combined with linseed; however, the rumen accumulation of SA in both groups supplemented with grape seed evidenced that this by-product was not effective in decreasing the BH of dietary polyunsaturated fatty acids (PUFA). [ABSTRACT FROM AUTHOR]