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Although more than 3 million head of dairy cows enter the food supply chain in the U.S. every year, research on this topic remains limited and scarce. Meat production from dairy cows is a significant component of beef production, accounting for almost 10% of U.S. commercial beef production. Thus, the purpose of this review is to demonstrate the importance of dairy cows as a beef source, and to provide an overview on topics from farm to meat product—culling, marketing, transportation, welfare, body composition and its relationship with lactation particularities, carcass characteristics, meat quality, and traceability. Current scientific evidence has shown that culling a dairy cow at an appropriate time has beneficial effects on cow welfare and, consequently, cow value. During marketing the dairy cow is visually evaluated for health and factors associated with its expected carcass value; thus, marketing a well-conditioned cow will ensure that the animal is fit for transportation and provides high carcass yield. However, limitations such as low body condition score, lameness or mobility problems, and visual defects remain persistent. Even though beef harvest plants accommodate cows in all body composition states, the current carcass grade system does not reflect the mature cow industry needs. Therefore, improvement of the grading system could maximize carcass utilization and increase cow carcass value by recognizing subprimal cuts that could be merchandised as whole muscle cuts. Lastly, implementation of a traceability system would unify information from the farm to harvest assisting the industry in making further advancements.

Clinical signs of photosensitivity in cattle can occur sporadically and unpredictably. It is believed that cases of photosensitivity may be underreported, causing inaccurate and inflated reports of mortality. Additionally, because secondary photosensitization in grazing cattle occurs with liver damage or dysfunction, photosensitivity can have many potential or associated causes. This case links a previous occurrence of coccidiosis to an outbreak of photosensitivity in grazing Holstein steers. Grazing management staff first observed clinical signs of photosensitivity 17 days after an outbreak of coccidiosis and subsequent turnout to spring pastures. Clinical signs were observed in 25% of the population. The severity of photosensitivity was variable and ranged from blistered skin on the muzzle to sloughing of unpigmented epidermis and thinly haired regions. Severely affected cattle were removed from pasture, housed under shade, monitored for infection, and recovered without treatment. Mild cases remained on pasture and recovered without treatment. Photosensitivity did not reoccur in the cattle that remained on pasture or in mildly affected cattle returned to pasture. Photosensitivity did not appear to be associated with pasture weeds, a specific forage species, or variable or extreme weather conditions that could have resulted in mycotoxin production. The occurrence appears to have been a result of a previous and concurrent coccidiosis outbreak that caused secondary photosensitization through hepatic lipidosis caused by anorexia and dehydration associated with the severe coccidiosis. Although clinical signs appeared suddenly, cattle recovered quickly and without treatment.

The objective of this study was to evaluate the role of reductive acetogenesis as an alternative H 2 disposal mechanism in the rumen. H 2 /CO 2 -supported acetogenic ruminal bacteria were enumerated by using a selective inhibitor of methanogenesis, 2-bromoethanesulfonic acid (BES). Acetogenic bacteria ranged in density from 2.5 × 10 5 cells/ml in beef cows fed a high-forage diet to 75 cells/ml in finishing steers fed a high-grain diet. Negligible endogenous acetogenic activity was demonstrated in incubations containing ruminal contents, NaH 13 CO 3 , and 100% H 2 gas phase since [U- 13 C]acetate, as measured by mass spectroscopy, did not accumulate. Enhancement of acetogenesis was observed in these incubations when methanogenesis was inhibited by BES and/or by the addition of an axenic culture of the rumen acetogen Acetitomaculum ruminis 190A4 (10 7 CFU/ml). To assess the relative importance of population density and/or H 2 concentration for reductive acetogenesis in ruminal contents, incubations as described above were performed under a 100% N 2 gas phase. Both selective inhibition of methanogenesis and A. ruminis 190A4 fortification (>10 5 CFU/ml) were necessary for the detection of reductive acetogenesis under H 2 -limiting conditions. Under these conditions, H 2 accumulated to 4,800 ppm. In contrast, H 2 accumulated to 400 ppm in incubations with active methanogenesis (without BES). These H 2 concentrations correlated well with the pure culture H 2 threshold concentrations determined for A. ruminis 190A4 (3,830 ppm) and the ruminal methanogen 10-16B (126 ppm). The data demonstrate that ruminal methanogenic bacteria limited reductive acetogenesis by lowering the H 2 partial pressure below the level necessary for H 2 utilization by A. ruminis 190A4.

Techniques were evaluated for formation of a liquid inoculum from shredded municipal refuse, including chilling the refuse at 4°C prior to blending and multiple washing and blending cycles. The average count of cellulolytic bacteria from six different detachment treatments was 5.1 × 10 4 cells per g (dry weight) of refuse with a range of 0.7 × 10 4 to 12.7 × 10 4 cells per g (dry weight). The liquid obtained from blending the refuse in phosphate buffer followed by hand squeezing was the selected detachment procedure. The inoculum formation procedure was validated by the addition of ruminal cellulolytic bacteria to refuse and recovery of the cellulolytic bacteria by most-probable-number enumerations. The ratio of measured to expected cell counts among tests in which different volumes of ruminal fluid were added to refuse ranged from 2.7 to 14.4. There was no evidence of anaerobic cellulolytic fungi in a refuse sample.