RESUMEN
The objective of this research was to investigate the influence of beef hot carcass weight (HCW) on consumer sensory attributes. Beef carcasses (n = 116) were selected based on the USDA quality grade and HCW. Lightweight (LW; 296-341 kg), middleweight (MW; 386-432 kg), or heavyweight (HW; 466-524 kg) carcasses with USDA Choice (LC) or USDA Select (SEL) quality grades were used in this study. Carcasses were tracked through fabrication and the semitendinosus, chuck roll, and strip loin were collected and fabricated into eye of round, Denver cut, and strip loin steaks, respectively, for consumer sensory evaluation. USDA Select MW Denver cut steaks had increased overall liking and texture liking scores and were more tender and juicier than the SEL LW steaks (p ≤ 0.02). USDA Select MW strip loin steaks had increased overall and flavor liking scores and were more tender than the SEL LW steaks (p ≤ 0.02). USDA Choice MW eye of round steaks had increased overall, flavor, and texture liking scores and were juicier than the LW eye of round steaks (p ≤ 0.04). The steaks evaluated in this study were differentially impacted by HCW and little to no clear pattern of effects could be determined across cut or quality grade. Additional research is needed to determine the most acceptable HCW from a consumer perspective.
RESUMEN
Fatty acids (FA) differ in their transfer efficiencies and metabolic partitioning and lactating cows provide a robust model to investigate kinetics of FA transport. The objective was to compare kinetics of n-3 polyunsaturated FA (PUFA) trafficking through plasma and into milk. In the first experiment, ten ruminally cannulated multiparous Holstein cows were used in a crossover design with 7 d periods. Cows were milked at 6 h intervals and abomasal treatments provided a single dose of 80.1 g of α-linolenic acid as free FA (ALA-FFA) or 45.5 g EPA and 32.9 g DHA (LCn3-FFA). Transfer of n-3 PUFA to milk was nearly 50% higher for ALA-FFA than LCn3-FFA (48.2 and 32.7% of the bolus) and fit a bi-exponential model. Rapid transport of n-3 PUFA, assumed to be directly through chylomicrons, was nearly twice as high in ALA-FFA than LCn3-FFA and the subsequent slow transport, assumed to be indirect transfer through tissue recycling, was over 2.5-fold higher in LCn3-FFA than in ALA-FFA. Plasma analysis revealed LCn3-FFA enriched phospholipids and cholesterol esters, which had a slow clearance. In the second experiment, 4 cows received a bolus of a mixture of ALA, EPA, and DHA prepartum while not lactating and around d 10, 55, and 225 of lactation. Transfer of ALA to milk did not differ between stages of lactation, but DHA was lower in early compared to mid and late lactation. In conclusion, dietary ALA is rapidly and efficiently transferred to milk in cows while EPA and DHA are rapidly incorporated into plasma or tissue fractions not available to the mammary gland. This demonstrates clear differences in trafficking and partitioning of n-3 PUFA that ultimately impact tissue and organelle enrichment with implications for effective doses.
