When winter temperatures are colder than normal, larger calf birth weights can be expected in the spring. This is especially true with more calving difficulty in two-year-old heifers.
A six-year study was conducted to investigate effects of winter temperatures on two-year-old cows and their subsequent calf birth weights and calving difficulty in the spring. The winter of 1992-1993 (coldest) was 11° F. colder than the winter of 1994-1995 (warmest).
The coldest winter was followed by calf birth weights that were 11 lbs. heavier with 29% greater calving difficulty compared to the warmest winter.
Study results reported in the “Ohio State University Veterinary Newsletter” (Vol. 26, No. 1, fall 1999) indicate that as average winter temperatures decreased 1° F, subsequent calf birth weights increased 1 lb. and calving difficulty increased 2.6%. Hide temperatures increased slightly, but calf birth weights were unchanged.
The first research on this topic was conducted at the U.S. Meat Animal Research Center, Clay Center, NE, 25 years ago. Genetically similar heifers were bred in Nebraska to the same sires. Half were wintered in Louisiana with the remainder staying in Nebraska. The difference in birth weight was 20 lbs. Submitted by Bill Kvasnicka, Extension veterinarian, University of Nevada, Reno, firstname.lastname@example.org.
An online video image analysis system more accurately predicted carcass cutout yields than online USDA graders, according to a Colorado State University (CSU) study. CSU researchers used 296 steer and heifer carcasses to evaluate the accuracy of four different methods of predicting fabricated yields of closely trimmed subprimals:
Whole yield grade numbers assigned by USDA graders online at chain speed (10-12 seconds/carcass);
Yield grades assigned off-line to the nearest 0.1 by expert USDA graders at a comfortable rate of speed;
A video image analysis system, “Computer Vision System” (CVS), to estimate carcass yield at chain speed;
CVS measured ribeye area in conjunction with expert grader estimates of the remaining yield grade factors (fat thickness, carcass weight, and percent of kidney, pelvic and heart fat).
Accuracies of the four systems were 39%, 67%, 64% and 65%, respectively. The authors concluded that prediction models using the CVS estimates — either alone or combined with some human grader estimates — more accurately predicted carcass cutout yields than did yield grades assigned by online graders (Cannell et al. 2002. J. Anim. Sci. 80: 1195).