Polyacrylamide vertical gel electrophoresis was used to separate the caseins of sows' milk. Polymorphism was found in a region of the gels designated Cn3. The Cn3 polymorphism consists of two bands which appear to be controlled by two codominant alleles designated Cn 3 A and Cn 3 B . Homozygotes possess one band and heterozygotes posses both bands of equal intensity giving the following phenotypes: Cn3A, Cn3AB, and Cn3B. A chi-square test for goodness of fit of the observed phenotypes to that expected by the Hardy-Weinberg equilibrium formula and a segregation analysis of eight matings involving 19 female progeny conform to the hypothesis that the Cn3 polymorphism is controlled by two codominant autosomal alleles. Further family studies will be necessary to confirm the genetic control of the Cn3 polymorphism.

One hundred twenty-eight pigs were used in a balanced 24 × 8 factorial experiment in which the two-level factors were year, breed (Yorkshire and Duroc), line (high- and low-fat) and diet (normal and 25% reduction in gross energy intake). The pigs were slaughtered at eight ages from 84 to 392 days. The high-fat line gained 8 and 16% slower than the low-fat line in the Yorkshires and Durocs, respectively. There was an over-all 20% reduction in rate of gain and a 4% improvement in feed efficiency when energy intake was reduced. There was a significant breed x line x diet effect on rate of gain as a result of the variable, within line response to energy restriction. Average carcass and fat weights were heavier (P<.01) for Durocs than Yorkshires and the reverse was true for weight of lean and bone. Low-fat lines had more total lean and bone and less fat than high-fat lines. There were average decreases of 34% in fat weight and 7% in weight of lean and bone because of dietary energy restriction. This restriction resulted in changes of +4, −12, −10 and −9% in weight of lean for high-fat and low-fat Yorkshires and high-fat and low-fat Durocs, respectively.

Carcasses from steers of varying age and carcass composition as a result of nutritional level were used to evaluate specific gravity as an indicator of carcass composition. The correlation of composition of beef carcass cuts to the composition of the carcass was determined also. Carcasses containing 20.00 to 29.99% fat had the highest correlation coefficients between specific gravity and percent moisture, fat and protein. These correlation coefficients, although statistically significant, were low. Thus, density appears to be a rather poor estimator of carcass composition. When ether extract of the carcass was less than 20%, specific gravity was not highly correlated to carcass composition. When steer carcasses contained over 40% fat, higher correlation coefficients were obtained between density and composition. Density of the wholesale cuts and 9–10–11th rib was more highly correlated to their composition than was the case with the entire carcass. The composition of the left 9–10–11th rib was highly correlated to its density. In this respect, this cut is superior to other carcass cuts. The chemical composition of the chuck, round, rib, 9–10–11th rib, sir loin and short loin was highly correlated to the composition of the carcass. As a result of high correlations between density and composition and the high correlation of the composition of the 9–10–11th rib to carcass composition, it appears that the density of the 9–10–11th rib would be a good indicator of carcass composition.

Eight selection indexes for weanling beef calves were developed and compared. These were based on daily gain from birth to weaning, 203-day weight, and type score. Selection on the basis of an index combining daily gain and type or weaning weight and type in the best linear equation was concluded to be preferable to selecting on the basis of either growth or type singly. Estimates of heritabilities, genetic and phenotypic correlations, and economic values were calculated.

The production of early milk fat lambs is the most important phase of the sheep enterprise in the native lamb states of central and southeastern United States. In these states grade ewes, either native or crossbred westerns, are bred to rams of the various mutton breeds to produce a desirable market lamb. The native ewes usually are predominantly grade Hampshires. The western ewes are generally crosses of Hampshire, Suffolk, Columbia, or Corriedale rams on grade range ewes of predominantly Rambouillet or Merino breeding. The most popular breeds of rams are Hampshire, Suffolk, Southdown, Shropshire, and Dorset. Many producers believe that certain breeds of rams sire lambs that are heavier at birth and have proportionally larger heads than certain other breeds, thus causing increased difficulty at lambing. Differences in birth weights due to breed of sire have been reported by Miller (1935); Spencer et al. (1942); Kincaid (1943); Kean and Henning (1949); Blackwell and Henderson (1955) ; and Carter et al. (1957). Miller (1935) and Neville et al. (1958) reported breed of sire differences in other body measurements.

The area of loin eye, carcass weight, the separable lean of a particular beef cut, and various linear carcass measurements were evaluated as to their usefulness for predicting total carcass leanness. The area of loin eye was associated with only 18% of the variation of separable carcass lean, and 5–30% of the variation in the separable lean of the more valuable cuts of beef. Likewise, the relationships of the various linear carcass measurements with either loin eye area or carcass separable lean were quite low. Carcass width and circumference measurements were more highly related to loin eye area, while the various linear measurements descriptive of carcass length were closely related to total lean. Bone weight of the entire carcass was highly related to total separable carcass lean (r=0.75). The separable lean of a particular cut of beef was found to be more descriptive of carcass leanness or muscling than either the area of loin eye or the various carcass measurements. Correlation coefficients between total separable carcass lean and the lean of various wholesale cuts were 0.95 with round, 0.93 with chuck, 0.81 with foreshank, 0.80 with sirloin, and 0.75 with shortloin. From the regression equations calculated from these data, total carcass lean was found to increase by 2.94 and 20.43 lb. for each pound increase in separable round or foreshank lean, respectively. The high relationship of the lean content in these and other beef cuts (especially the round), to the total lean of the carcass is indicative of their usefulness to predict total carcass muscling in a particular beef carcass.

for the past 4 years the X-ray method of detecting animals heterozygous for “Snorter” dwarfism has been investigated. This method is based on vertebrae abnormalities as shown on radiographs of young calves. This study includes the radiographs of some 1500 calves representing several different lines of breeding in both the Hereford and Angus breeds. Also, include in this study are the test mating results of 89 animals (80 heifers, 9 bulls) X-rayed as calves. The data presented indicate: The X-ray method is highly accurate in identifying “Snorter” dwarf calves. There is considerable overlap within the range of normal morphology to mild vertebrae abnormality between presumed non-carrier and carrier animals. Radiographs of a bull's progeny may be used as a general method of predicting his dwarfism status before actually progeny testing him. However, the X-ray method is not recommended to the breeder as a basis for identification of individual animals with respect to genotype for dwarfism.