Effect of extruded linseeds alone or in combination with fish oil on intake, milk production, plasma metabolite concentrations and milk fatty acid composition in lactating goats

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Comparison of the nutritional regulation of milk fat secretion and composition in cows and goats.

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Comparison of ruminal lipid metabolism in dairy cows and goats fed diets supplemented with starch, plant oil or fish oil

16 páginas, 5 tablas, 1 figura.Direct comparison of cow and goat performanceand milk fatty acid responses to diets known to inducemilk fat depression (MFD) in the bovine revealsrelevant species-by-diet interactions in ruminal lipidmetabolism. Thus, this study was conducted to inferpotential mechanisms responsible for differences in therumen microbial biohydrogenation (BH) due to dietand ruminant species. To meet this objective, 12 cowsand 15 goats were fed a basal diet (control), a similardiet supplemented with 2.2% fish oil (FO), or a dietcontaining 5.3% sunflower oil and additional starch(+38%; SOS) according to a 3 × 3 Latin square designwith 25-d experimental periods. On the last day of eachperiod, fatty acid composition (by gas chromatography)and bacterial community (by terminal-RFLP),as well as fermentation characteristics, were measuredin rumen fluid samples. Results showed significant differencesin the response of cows and goats to dietarytreatments, although variations in some fermentationparameters (e.g., decreases in the acetate-to-propionateratio due to FO or SOS) were similar in both species.Main alterations in ruminal BH pathways potentiallyresponsible for MFD on the SOS diet (i.e., the shiftfrom trans-11 to trans-10 18:1 and related increases intrans-10,cis-12 18:2) tended to be more pronounced incows, which is consistent with an associated MFD onlyin this species. However, changes linked to FO-inducedMFD (e.g., decreases in 18:0 and increases in totaltrans-18:1) were stronger in caprine rumen fluid, whichmay explain their unexpected susceptibility (althoughless marked than in bovine) to the negative effect ofFO on milk fat content. Altogether, these results suggestthat distinct ruminal mechanisms lead to eachtype of diet-induced MFD and confirm a pronouncedinteraction with species. With regard to microbiota,differences between cows and goats in the compositionof the rumen bacterial community might be behindthe disparity in the microorganisms affected by theexperimental diets (e.g., Ruminococcaceae, Lachnospiraceae,and Succinivibrionaceae in the bovine, andPseudobutryrivibrio, Clostridium cluster IV, Prevotella,and Veillonellaceae in the caprine), which hinderedthe assignation of bacterial populations to particularBH steps or pathways. Furthermore, most relevantvariations in microbial groups corresponded to as yetuncultured bacteria and suggest that these microorganismsmay play a predominant role in the ruminal lipidmetabolism in both cows and goats.This study was supported by INRA (UMR1213; France) and the Spanish Ministry of Economy and Competitiveness (MINECO; AGL2014-54587). P. G. Toral was granted a postdoctoral fellowship from Fundación Alfonso Martín Escudero (Madrid, Spain) and a research contract from the MINECO (Juan de la Cierva program).Peer reviewe

Rapeseed or linseed in dairy cow diets over 2 consecutive lactations:Effects on adipose fatty acid profile and carry-over effects on milk fat composition in subsequent early lactation

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High NEFA concentrations around parturition are associated with delayed ovulations in grazing dairy cows

The objectives of this study were to assess indicators of metabolic status of grazing dairy cows around parturition, and the relationship between these indicators with the resumption of ovulations postpartum (ROP). Holstein multiparous cows (N=20) grazing on improved pastures and supplemented with concentrates were body condition scored and tail bled weekly from wk −2 through +9 related to parturition. Plasma samples were analyzed for nonesterified fatty acids (NEFA), leptin, insulin-like growth factor-1 (IGF-1) and progesterone (P4). Data were analyzed with mixed models, logistic regression, with receiver operator characteristic (ROC), and Cox regression analysis. Cows having Delayed Ovulation ([DO], ROP on week ≥5) had lower BCS, and higher NEFAs than cows having a normal ROP around parturition (BCS: 2.73±0.08 vs. 2.94±0.05, Pb0.05, and NEFA: 0.43±0.04 vs. 0.35±0.02 mM, Pb0.10, respectively). Also, DO cows had lower BCS than normal herdmates (2.59±0.10 vs. 2.99±0.06, Pb0.01) around time of ROP, but they had similar NEFA, leptin and IGF-1. The risk for DO increased as NEFA increased (0.4% and 0.5% per every increasing mM of NEFA in prepartum and postpartum, respectively). The ROC curve showed that NEFA (prepartum and postpartum) had areas of 0.85 and 0.80, and cut-off values of 0.39 and 0.47 mM. Finally, hazard for ROP increased as prepartum IGF-1 increased, and it decreased as postpartum NEFA increased. In conclusion, cows with lower BCS and higher prepartum and postpartum NEFA had higher odds for getting DO than herdmates with greater BCS and lower NEFA concentrations.Facultad de Ciencias Veterinaria

Chemical markers for rumen methanogens and methanogenesis

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