RESUMEN
Despite a high volume of market (cull) dairy cows entering the food chain every year, beef from market dairy cows is largely considered insignificant when compared with beef from beef cattle in the market and is widely thought to be used for ground beef only. Our study aimed to evaluate the effects of feeding dairy market cows on a lactating TMR diet before slaughter on carcass and beef quality traits. Forty-three Holstein market cows were randomly assigned into 2 treatments: Fed or Direct. Fed cows (n = 22) were dried off, then fed a lactating cow TMR ration for approximately 60 d whereas Direct cows (n = 21) were sent directly to slaughter. Hot carcass weight (HCW) was used to calculate the dressing percentage (DP) together with the animals' body weight recorded when animals left the farm to go to the abattoir. At 24h post-mortem, the rib fat thickness (RFT) and rib eye area (REA) were measured by a certified grader. Afterward, rib samples were collected between the 12th -10th ribs from one side of the carcass and divided into 5 ribeye steaks. The first steak was used for intramuscular fat (IMF) content analysis by NIRS. The other 4 steaks were then aged for 7, 14, 21, or 28 d. Following aging, the steaks available were assessed for tenderness using the Warner-Bratzler Shear Force protocol. Data were analyzed by mixed linear regression to compare experimental groups for continuous outcomes. HCW of the Fed cows was higher than the Direct cows, with a mean HCW of 408.3 kg and 326.1 kg, respectively (SE ± 9.0). Average DP in Fed cows was 49.1%, compared with 42.5% in Direct cows (SE ± 0.69). The average percentage of IMF in Fed cows was 8.1% and in Direct cows was 5.0% (SE ± 0.43). Fed cows had a mean REA of 68.1 cm2 and Direct cows had a mean of 57.7 cm2 (SE ± 11.9). No differences were found for RFT. The steaks aged for 14 d resulted in meat with a mean shear force (SF) of 4.19 kg in Fed cows, while Direct cows had a mean SF of 6.28 kg (SE ± 0.29) Feeding market dairy cows for 60 d before slaughter enhanced carcass weight and yield, IMF content, and tenderness. These results indicate that approximately 60 d of feeding can improve the quality of market dairy cow meat and may help improve market cow value.
RESUMEN
The welfare of cull cows during transport to slaughter is a current concern in the Canadian dairy industry. Cull cows sold through auction often have a high prevalence of lameness, low BCS, hock lesions, and udder engorgement. To evaluate whether drying off and feeding cull dairy cows before transport can mitigate these challenges, 45 cows designated for culling were randomly assigned to either be fed for 60 d after being dried off (fed group; n = 24) or to serve as controls by being sent directly to slaughter (direct group; n = 21). Two fed group cows were removed for health reasons before completing the feeding period. Both fed group and direct group cows were assessed for locomotion (5-point scale), BCS (5-point scale), hock lesions (3-point scale), udder engorgement (3-point scale), and BW at the time of enrollment. Fed group cows, locomotion, BCS, hock, and udder engorgement scores were assessed weekly until slaughter. Weights of the fed group cows were measured again the day before slaughter. Mixed linear regression models were used to assess continuous outcomes BCS and weight. Mixed logistic regression models were used to assess dichotomous outcomes presence of hock lesions and lameness. Fed group cows gained an average of 116.9 kg over the feeding period (SE ± 8.20). Fed group cows had an average weight at slaughter of 834.2 kg, whereas direct group cows' average weight was 767.3 kg (SE ± 26.8). The fed group cows' average BCS at the start of the trial was 2.4, and at slaughter was 3.6, with an average gain of 1.2 BCS points. At slaughter, the proportion of udders involuted in the fed group was 45.1% (10/22) and in the direct group cows, was 0% (0/21). No differences were found in locomotion or hock lesions between the fed group and direct groups. It is important to weigh potential benefits for the fed group cows with the fact that direct group cows did not endure a drying off procedure, nor were they placed at risk of potential adverse health events. However, despite these potential limitations, due to the improved BCS and udder engorgement scores, cows fed for 60 d may be better prepared for the transportation to slaughter, as well as sell for a higher price due to increased BW and body condition.