No abstract

The development and life performance of 404 high-producing Holstein dairy cows was studied from birth onwards and during two lactations. The management, environment and parental genetics of the cows were known in detail. Cluster analysis identified four performance 'types': high-yielding (HY) cows and persistently high-yielding (PHY) cows, which accounted for 33% of the animals; medium-yielding (MY) cows, 41%; and low-yielding (LY) cows, 26%. Prenatal determinants of the life performance of the progeny were analyzed. Developmental and environmental factors were excluded as determinants of performance (including birth weight, level of passive immunity transfer, growth rate, age at first parturition and reproductive efficiency). Life performance did show minor seasonal effects, with more HY cows but less PHY being born during the cold season (90.1% in HY; 58.3% in PHY v. 81.5%). Instead, the single most important factor influencing life performance of daughters was maternal age. HY cows were born from the youngest mothers (1.89±1.14 parturitions, 3.12±1.42-year old), whereas LY cows were born from the oldest (2.72±1.80 parturitions, 3.97±2.01-year old; P<0.001). Life performance of the dams did not differ among clusters. In addition, metabolic parameters (fat and protein yield) were found to correlate significantly with yields between the first and second lactations (milk yield: r=0.357; fat yield: r=0.211; protein yield: r=0.277; P<0.0001), suggesting the influence of the individual. These results suggest that under optimal health, nutritional and environmental conditions, maternal aging is an important determinant of the life performance of progeny and argue for the need to identify conditions that contribute to health and disease in progeny according to the Developmental Origin of Health and Disease or DOHaD concept. Our findings may help the development of novel management guidelines for dairy farms.

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The objective of this retrospective study was to investigate the prevalence of pregnancy loss (PL; between 28–110 pregnancy days) and its relationship with factors: farm, year (2015–2018), season, artificial insemination (AI)-rank, parity, AI-type (fixed-time vs. oestrus-AI), previous PL, days in milk (DIM), fixed-time-AI protocol, AI-technician, bull, and semen-type (sexed vs. conventional). Data of 19,437 Holstein cattle AIs from eight Spanish farms were studied. Overall conception rate was 34.3% (6696/19,437) and PL 12.3% (822/6696). The PL was more likely to occur in primiparous (10.8%, odds ratio (OR) = 1.35; p = 0.04) and multiparous (15.3%; OR = 2.02, p < 0.01) than in heifers (PL = 6.9%, reference). Pregnancies achieved with AI after observed oestrus and natural breedings were associated with less PL than pregnancies after fixed-time-AI (12.7 vs. 11.9%; OR = 0.12, p = 0.01). First AIs related to higher PL than ≥2nd AIs (PL = 13.8% vs. 11.2; OR = 0.73, p < 0.01). The factors season, fixed-time-AI protocol, DIM, bull, AI-technician, or type of semen were not significantly associated with PL. Therefore, farmers and consultants should adapt their preventive strategies relating to PL, particularly, to the parity of the cattle.

A high intramuscular fat content characterizes Wagyu (WY) cattle breed. Our objective was to compare beef from WY, WY-by-Angus, or Wangus (WN) steers with European, Angus-by-Charolais-Limousine crossbred steers (ACL), considering metabolic biomarkers pre-slaughtering and nutritional characteristics, including health-related indexes of the lipid fraction. The fattening system with olein-rich diets and no exercise restriction included 82 steers, 24 WY, 29 WN, and 29 ACL. The slaughter ages and weights were (median and interquartile range) 38.4 mo.-old (34.9–40.3 mo.) and 840 kg (785–895 kg) for WY; for WN, 30.6 mo. (26.9–36.5 mo.) and 832 kg (802–875 kg), and for ACL steers, 20.3 mo.-old (19.0–22.7 mo.) and 780 kg (715–852 kg). Blood lipid-related metabolites, except for non-esterified fatty acids (NEFA) and low-density level cholesterol (LDL), were higher in WY and WN than in ACL, while glucose was lower in WY and WN. Leptin was higher in WN than in ACL. Pre-slaughtering values of plasma HDL underscored as a possible metabolic biomarker directly related to beef quality. The amino-acid content in beef did not differ among experimental groups, except for more crude protein in ACL. Compared to ACL, WY steers showed higher intramuscular fat in sirloin (51.5 vs. 21.9%) and entrecote (59.6 vs. 27.6%), more unsaturated fatty acids in entrecote (55.8 vs. 53.0%), and more oleic acid in sirloin (46 vs. 41.3%) and entrecote (47.5 vs. 43.3%). Compared to ACL entrecote, WY and WN showed better atherogenic (0.6 and 0.55 vs. 0.69), thrombogenicity (0.82 and 0.92 vs. 1.1), and hypocholesterolemic/hypercholesterolemic index (1.9 and 2.1 vs. 1.7). Therefore, beef’s nutritional characteristics depend on breed/crossbred, slaughtering age and cut, with WY and WN entrecote samples showing a healthier lipid fraction.