Phenotypic and genetic characterisation of methane emission predicted from milk fatty acid profile of Sarda dairy ewes

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

Effects of grape seed supplementation, alone or associatedwith linseed, on ruminal metabolism in Sarda dairy sheep

Grape seed is a by-product of the winery and distillery industry which could be used inanimal nutrition. To test the hypothesis that dietary supplementation with this by-productcan decrease the biohydrogenation (BH) of healthy fatty acids (FA), the present study evalu-ated the effects of grape seed supplementation, alone or combined with linseed, on ruminalBH processes in dairy sheep. In this 60-d trial, 24 lactating Sarda dairy ewes were assignedto four homogeneous groups and fed as follows: (1) control diet (CON), (2) a diet supple-mented with 300 g/d per head of grape seed (GS), (3) a diet supplemented with 220 g/d perhead of extruded linseed (LIN), (4) and a diet supplemented with a mix of both grape seedand linseed (300 and 220 g/d per head, respectively) (MIX). Ammonia, pH, volatile fattyacids (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&gt;0.05). The ammonia content wasincreased (P&lt;0.05) in GS and MIX compared with LIN and CON. The molar proportions ofacetate and propionate and their ratio were not affected by the diet (P>0.05), whereas themolar 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&lt;0.05),whereas the percentage of vaccenic acid (VA; C18:1 trans-11) tended to increase (P&lt;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&lt;0.05), whereas RA did not differ between the same groups. The con-centration of linoleic acid (LA; C18:2 n–6) decreased and stearic acid (SA; C18:0) increasedin all supplemented groups, whereas linolenic acid (LNA; C18:3 n–3) decreased in the twogroups receiving grape seed compared with CON and LIN. The concentration of total odd-and branched-chain fatty acids (OBCFA) decreased in all supplemented groups comparedwith CON (P&lt;0.05), evidencing that grape seed and linseed supplementation influencedthe ruminal BH processes. Grape seed was able to increase the accumulation of RA whensupplemented alone, and of VA when combined with linseed; however, the rumen accumu-lation of SA in both groups supplemented with grape seed evidenced that this by-productwas not effective in decreasing the BH of dietary polyunsaturated fatty acids (PUFA)

Effects of diets containing grape seed, linseed, or both on milk production traits, liver and kidney activities, and immunity of lactating dairy ewes

This study aimed to evaluate the effects of the dietary inclusion of grape seed, alone or in combination with linseed, on milk production traits, immune response, and liver and kidney metabolic activity of lactating ewes. Twenty-four Sarda dairy ewes were randomly assigned to 4 dietary treatments consisting of a control diet (CON), a diet containing 300 g/d per head of grape seed (GS), a diet containing 220 g/d per head of extruded linseed (LIN), and a diet containing a mix of 300 g/d per head of grape seed and 220 g/d per head of extruded linseed (MIX). The study lasted 10 wk, with 2 wk of adaptation period and 8 wk of experimental period. Milk yield was measured and samples were collected weekly and analyzed for fat, protein, casein, lactose, pH, milk urea nitrogen, and somatic cell count. Blood samples were collected every 2 wk by jugular vein puncture and analyzed for hematological parameters, for albumin, alkaline phosphatase, bilirubin, creatinine, gamma glutamyltransferase, aspartate aminotransferase, alanine aminotransferase, protein, blood urea nitrogen, and for anti-albumin IgG, IL-6, and lymphocyte T-helper (CD4+) and lymphocyte T-cytotoxic (CD8+) cells. On d 0, 45, and 60 of the trial, lymphocyte response to phytohemagglutinin was determined in vivo on each animal by measuring skin-fold thickness (SFT) at the site of phytohemagglutinin injection. Humoral response to chicken egg albumin was stimulated by a subcutaneous injection with albumin. Dietary treatments did not affect milk yield and composition. Milk urea nitrogen and lactose were affected by diet × period. Diets did not influence hematological, kidney, and liver parameters, except for blood urea nitrogen, which decreased in LIN and increased in MIX compared with CON and GS. Dietary treatments did not alter CD4+, CD8+, and CD4+-to-CD8+ ratio. The SFT was reduced in GS and MIX and increased in LIN compared with CON. The IgG and IL-6 were affected by diet × period. The reduction in IgG on d 60 and SFT in ewes fed GS suggests an immunomodulatory effect of this residue. The limited variation in milk and hematological and metabolic parameters suggests that GS and LIN can be included, alone or in combination, in the diet of dairy ewes without adverse effects on milk production and health status

Use of principal component analysis for revealing and understanding differences in milk fatty acid profile in different ruminant species

Fatty acid (FA) profile is a crucial factor in defining milk properties and quality. Increasing attention is placed on those FA having a positive role on human health, such as polyunsaturated FA (PUFA), oleic acid, vaccenic acid and conjugated linoleic acid (CLA). In the present work, the FA profile obtained from gas-chromatographic analysis of 703 individual milk samples (289 cows, 214 buffaloes and 200 ewes), were used to evaluate the suitability of principal component (PC) analysis (PCA) to investigate differences in milk FA profile among these species. Thirty-six FA were analyzed by PCA. The first and second PC (PC1 and PC2) accounted for 51% of the total variability (30%, 21%, for PC1, PC2, respectively). Elements of eigenvector of PC1 were positively associated with few FA, including C16:0 (0.50), the most abundant FA in milk of the 3 species (~29.3% of FA). Among those negatively correlated with PC1, some relevant FA for human health were retrieved: C18:1t11 (−0.75), CLAc9t11 (−0.79), C18:3n-3 (−0.76), EPA (−0.81) and DPA (−0.89). Negative correlations with PC2 were observed, in general, for medium chain FA (e.g., C15:0, C16:0), whereas long chain FA (e.g., C18:1 isomers, C18:2n-6 and other PUFA) exhibited positive values. Score values of PC1 and PC2 allowed the description of the relationship among animals based exclusively on the milk FA profile, revealing a clear discrimination of the 3 species: PC1 discriminated ewes milk from that of cows and buffaloes, whereas, PC2 was able to discriminate cows from buffaloes, with ewes showing intermediate values. In general, the use of PCA evidenced as a great part of variance of FA profile of ruminants (PC1) is related to the distinction between small or large ruminants, also evidencing higher amount of beneficial FA for ewes. An important part of variance (PC2) indicates as ewes milk FA has intermediate characteristics compared with cow and buffalo mil