To explore the potential of cattle to produce both milk and beef, the genetic aspects of beef production among Holstein-Friesian bulls pedigree selected for milk were studied. The data included growth records of 504 bulls (DPT) by 120 sires (SPT) pedigree selected for progeny testing by American Breeders Service, 1964 to 1971. DPT bulls with proofs had an average predicted difference for milk (PMD) of +180 kilograms. The daughter average was 7,273 kg per lactation under varying herd conditions. Sires accounted for 10% of the variation in average daily gain (ADG), 10% in daily gain per 100 kg body weight (DG/100) and 16% in body weight, indicating substantial genetic variability in beef traits. Sire variance components for beef traits varied with age. There were wide ranges in estimated breeding value (EBV) and estimated transmitting ability (ETA) for beef traits among DPT and SPT bulls, respectively. Ranking EBV among DPT bulls and ETA among SPT bulls for beef traits and selecting the top 10% and 20%, respectively, showed high selection differentials, empirically reflecting the potential for genetic improvement from selection. TO explore the potential of cattle to produce both milk and beef, the genetic aspects of beef production among Holstein-Friesian bulls pedigree selected for milk were studied. The data included growth records of 504 bulls (DPT) by 120 sires (SPT) pedigree selected for progeny testing by American Breeders Service, 1964 to 1971. DPT bulls with proofs had an average predicted difference for milk (PMD) of 4180 kilograms. The daughter average was 7,273 kg per lactation under varying herd conditions.Sires accounted for 10% of the variation in average daily gain (ADG), 10% in daily gain per 100 kg body weight (DG/100) and 16% in body weight, indicating substantial genetic variability in beef traits. Sire variance components for beef traits varied with age. There were wide ranges in estimated breeding value (EBV) and estimated transmitting ability (ETA) for beef traits among DPT and SPT bulls, respectively.Ranking EBV among DPT bulls and ETA among SPT bulls for beef traits and selecting the top 10% and 20%, respectively, showed high selection differentials, empirically reflecting the potential for genetic improvement from selection.Average genetic correlations of milk production with beef traits ranged from 0.02 to 0.28 for body weight, from 0.02 to 0.26 for ADG, and from 0.01 to 0.20 for DG/100. Genetic correlations between milk and beef traits were low but positive, indicating emphasis could be shifted to either milk or beef without adverse effect on the other.Holstein-Friesians pedigree selected for milk1 The authors wish to acknowledge the cooperation of the

Abnormal oxidative processes including a reduction in thiamine-dependent enzymes accompany many neurodegenerative diseases. Thiamine deficiency (TD) models the cellular and molecular mechanisms by which chronic oxidative aberrations associated with thiamine-dependent enzyme deficits cause selective neurodegeneration. The mechanisms underlying selective cell death in TD are unknown. In rodent TD, the earliest region-specific pathological change is breakdown of the blood-brain barrier (BBB). The current studies tested whether nitric oxide and microglia are important in the initial events that couple BBB breakdown to selective neuronal loss. Enhanced expression of endothelial nitric oxide synthase and nicotinamide adenine dinucleotide phosphate diaphorase reactivity in microvessels, as well as the presence of numerous inducible nitric oxide synthase-immunoreactive microglia, accompanied the increases in BBB permeability. Nitric oxide synthase induction appears critical to TD pathology, because immunoreactivity for nitrotyrosine, a specific nitration product of peroxynitrite, also increased in axons of susceptible regions. In addition, TD elevated iron and the antioxidant protein ferritin in microvessels and in activated microglia, suggesting that these cells are responding to an oxidative challenge. All of these changes occurred in selectively vulnerable regions, preceding neuronal death. These findings are consistent with the hypothesis that the free radical-mediated BBB alterations permit entry of iron and extraneuronal proteins that set in motion a cascade of inflammatory responses culminating in selective neuronal loss. Thus, the TD model should help elucidate the relationship between oxidative deficits, BBB abnormalities, the inflammatory response, ferritin and iron elevation, and selective neurodegeneration.

Growth records of 504 pedigree selected Holstein-Friesian bulls by 120 sires collected for progeny testing at the American Breeders Service, Inc., DeForest, Wisconsin from 1964 to 1971, were studied to determine the shape of the growth curve, relationships among body weights and growth rates at various ages and to estimate heritability of growth. Body weight and average/daily gain were consistently higher than the previous growth standards for Holstein-Friesian bulls. Bulls weighed about 480 kg at 15 months, which was 46% of average mature weight. Average daily gain ranged from 1.3 to 0.8 kg between 6 and 18 months of age. A sustained high rate of gain was observed even beyond recommended slaughter age which clearly shows that Holstein-Friesian bulls with potentially high milk production levels also have a good capacity to produce beef. Body weights, expressed as deviations from contemporary group averages, at successive ages were positively correlated but the relationships declined as intervals between ages increased, indicating that using earlier weights to predict later weights would be effective only at shorter age intervals. There were no definite relationships between growth rates at subsequent ages, implying that growth rates obtained for a certain age range should be applied only for that particular age range. Correlations between body weight and growth rates were largely negative, suggesting that heavier animals at certain ages tended to gain less in subsequent periods. Within group heritabilities for body weight increased with age from 6 to 30 months of age but gradually declined thereafter. The trends for average daily gain (ADG) and daily gain per 100 kg body weight (DG/100) were almost the opposite for body weight. The overall average heritability estimates for body weight, ADG and DG/100 were 0.83, 0.44 and 0.46, respectively. Since the majority of the Holstein-Friesians being born are progeny of AI sires, the values for growth rate will serve as a standard for Holstein-Friesian males. Body weight and average~daily gain were consistently higher than the previous growth standards for Holstein-Friesian bulls. Bulls weighed about 480 kg at 15 months, which was 46% of average mature weight. Average daily gain ranged from 1.3 to 0.8 kg between 6 and 18 months of age. A sustained high rate of gain was observed even beyond recommended slaughter age which clearly shows that Holstein-Friesian bulls with p3tentially high milk production levels also have a good capacity to produce beef.Body weights, expressed as deviations from contemporary group averages, at successive ages were positively correlated but the relationships declined as intervals between ages increased, indicating that using earlier weights to predict later weights would be effective only at shorter age intervals. There were no definite relationships between growth rates at subsequent ages, implying that growth rates obtained for a certain age range should be applied only for that particular age range. Correlations between body weight...

A selection index combining milk and beef production traits, such that progress in aggregate economic value is maximized, was constructed for Holstein bulls. The index for milk was IM = 1.11Xt + .997X2 while the index for beef trait was IB = .008X~ + .619X~ where X~ is the daughters' average lactation yield (kg) and X2, bulls' body weight at 15 mo (kg).The relative genetic progress from simultaneous selection for milk and beef traits with different emphasis was estimated. Expected genetic progress in beef production (body weight at 15 mo) dedined with increasing selection on milk and vice versa. Expected genetic progress, however, did not fall below onethird of maximum genetic progress (100%) for either milk or beef, regardless of the emphasis of seleetion.Based on current milk and beef values, ignoring milk and selecting solely for beef would give the highest genetic progress in total economic value but quite slow genetic progress in total protein production. Ignoring beef and seleering solely for milk would give the highest genetic progress in total protein production and a fairly high genetic progress in total economic value. A 1:7 beef to milk emphasis per standard deviation seems to be most appropriate since it results in large genetie progress in both total protein and total economie Value.