Carcass Fat Percentage Research Articles

Effect of trimethylamine oxide and betaine in swine diets on growth performance, carcass characteristics, nutrient digestibility, and sensory quality of pork.

Two growth experiments and one digestibility experiment were conducted to study the effect of trimethylamine oxide (TMAO) and betaine in swine diets. In Exp. 1, 36 limit-fed pigs averaging 19.1 kg in initial weight were used to study the effect of adding TMAO at 10 g/kg of feed or betaine at an equivalent level of methyl groups (10.5 g/kg feed) to a high-fat (11.3% ether extract) basal diet. Dietary addition of TMAO increased ADG by 61 g/d, reduced number of days to market by 8.3 d (P<.02), and tended (P<.09) to improve gain/feed (G/F) compared with the control diet. Betaine had no effect on growth performance of pigs. Adding TMAO or betaine to diets had no effect on percent carcass fat, percent carcass lean, or dressing percentage. Dietary supplementation of TMAO reduced (P<.05) plasma triacylglycerol level (TAG) compared with the control diet. There was no effect of dietary TMAO or betaine on sensory quality characteristics of pork. In Exp. 2, 48 ad libitum-fed pigs averaging 21.7 kg initial BW and 104.7 kg final BW were used to determine the effect of adding low and intermediate levels of TMAO (1, 2, or 5 g/kg) to diets. Adding 1 g of TMAO increased G/F (P<.01) compared with control pigs. When using orthogonal contrasts, adding 2 g of TMAO reduced (P<.05) P2 backfat thickness and tended to increase (P<.09) lean percentage compared with the control diet. Trimethylamine oxide gave a quadratic effect (P<.05) on plasma TAG levels. Adding 1 and 2 g of TMAO increased plasma TAG, but 5 g of TMAO decreased it compared with the control diet. In Exp. 3, 12 barrows of 42.3 kg average initial BW and 50.0 kg final BW were used to investigate the effect of supplementing diets with 1 g of TMAO and 1.27 g of betaine/kg of feed on apparent total tract nutrient digestibility. The addition of TMAO increased (P<0.03) apparent total tract digestibility of fat (HCl-EE). Betaine had no such effect. Adding TMAO to diets influenced growth performance and carcass quality in a dose-dependent manner.

Características de carcaça e da carne de novilhos de diferentes genótipos de Hereford x Nelore

O objetivo deste experimento foi avaliar as características de carcaça e da carne de novilhos Hereford (H), 5/8 H 3/8 Nelore (N), 1/2 H 1/2 N e 1/4 H 3/4 N, terminados em confinamento dos 20 aos 24 meses de idade. Vinte quatro novilhos tomados aleatoriamente do mesmo rebanho foram usados. A dieta alimentar continha, na matéria seca, 12,7% de proteína bruta e uma relação de volumoso:concentrado de 57,5:42,5. O volumoso foi composto de silagem de milho + cana-de-açúcar (relação 1:1). O peso de abate e o de carcaça fria foram maiores nos novilhos 1/2 H 1/2 N (443 and 236 kg), seguidos pelos 5/8 H 3/8 N (426 e 225 kg). O rendimento de carcaça aumentou com o acréscimo de sangue N, sendo 48,91; 52,74; 53,37; e 54,23%, respectivamente. Não houve diferença para espessura de gordura subcutânea da carcaça e porcentagem de osso, músculo e gordura na carcaça. A maciez da carne decresceu à medida que aumentou a porcentagem de Nelore no cruzamento.

Addition of fat to the diets of lactating sows: I. Effects on milk production and composition and carcass composition of the litter at weaning.

In Exp. 1 two groups of 18 sows were used to evaluate the effects of supplemental dietary fat on sow and litter performance and milk production and composition. Sows were provided ad libitum access to either a corn-soybean meal (control) diet or a similar diet containing 10% tallow. Feed intake, ME intake, and milk yield did not differ (P > .10) between treatments. The percentage of solids in milk was greater (P < .05) for sows fed the tallow diet, due to an increase (P < .05) in the fat and ash content. Compared with percentages of fatty acids in milk of sows fed the control diet, the percentages of C10:0, C14:0, C16:0, C16:1, and C18:3 fatty acids were lower (P < .05) and the percentages of C18:0 and C18:1 fatty acids were higher in milk of sows fed tallow diets (P < .05). In Exp. 2, 30 sows were fed diets similar to those fed in Exp. 1, and the effects of a tallow diet on pig carcass composition at weaning were determined. Litter size was standardized to 10 pigs. There were no differences (P > .10) in ADFI of sows. Daily ME intake was greater for sows fed tallow than for control sows during wk 2 (P < .05), wk 3 (P < .10), and the entire lactation (P < .05) period. Litter weaning weight was greater (P < .05) for pigs from sows fed tallow diets than for pigs from control sows. Pigs from tallow-fed sows had greater carcass fat weight and fat percentages (P < .05) and lower water and protein percentages (P < .05). These data indicate that the increased fat content of milk from sows fed tallow diets resulted in an increased weight gain for litters nursing these sows. The composition of the increased weight gain is almost exclusively fat.

Effect of various dietary nutrient density on the growth performance of local male ducks and their crosse

Three hundred day-old male ducklings were allocated randomly into 12 treatment combinations in 3 x 4 factorial design . Three levels of dietary density ration i.e : Low(12% /2,000 kcal), medium (16%/2,500 kcal) and high (20%/3,000 kcal) and 2 breeds of local ducks Tegal (TT) and Mojosari (MM) and their crossbreds (Tegal x Mojosari (TM) and Mojosari x Tegal (MT)) were applied. Each treatment combination consisted of5 replicates, each of 5 birds. The experiment was carried out for 8 weeks and measurements were weekly feed intake, body weight, weight and/or percentage of carcass, internal organs and abdominal fat. Results indicated that no significant interaction was detected between dietary nutrient density and the breeds of ducks on all parameters measured . Breeds of duck, as well as their crosses did not affect growth performance and other parameters . On the other hand, nutrient density influenced growth performance significantly, except for percentage of carcass and internal organs . In general, feed intake, body weight gain, feed efficiency, carcass weight and abdominal fat of ducks fed low density ration were significantly lower than those fed medium density, which were also lower than those fed high nutrient density diet . Weghtand length of intestine and kidney weight, of ducks fed low density diet however, were higher than the two other treatments . Keywords : Dietary density ration, breeds of duck, growth

Fattening heifers to heavy weights to enhance marbling: Efficiency of gain

Feedlot performance and carcass composition were measured in two studies to evaluate the use of common Canadian breeds and nutrition programs for production of highly marbled beef for the Japanese market. Weaned heifer calves (n = 221, initial weight 265 kg) of Angus, Hereford, and Hereford × Angus (HA) breeding were slaughtered at 500, 590, and 680 kg in exp. 1. In exp. 2, yearling heifers (n = 216, initial weight 395 kg, same breeds as exp. 1 but including Holstein) were slaughtered at 590 and 680 kg. Cattle were randomly assigned to either a high plane of nutrition (HP) until slaughter or a moderate plane of nutrition to 500 kg (exp. 1) or 550 kg (exp. 2), followed by a high plane to slaughter (MHP). Mean days on feed, percent carcass fat, and percent intramuscular fat in longissimus muscle were 347 d, 38.6%, and 8.50% in exp. 1, and 281 d, 37.5%, and 7.87%, respectively, in exp. 2. In exp. 1, Herefords produced the most economical gains but the fattest carcasses (P &lt; 0.05). In exp. 2, Holsteins had the most economical liveweight and lean carcass weight gains (P &lt; 0.05). The cost of a percentage increase in intramuscular fat was lowest for Angus in exp. 1 (P = 0.05), similar for the breeds in exp. 2 (P = 0.29), and not affected by slaughter weight group. HP cattle gained liveweight, carcass, lean carcass, and intramuscular fat more economically than did MHP cattle (P ≤ 0.0002). The rate of deposition of intramuscular fat did not appear to increase with maturity. Feeding cattle to extreme slaughter weights using conventional feedlot diets produced extremely fat carcasses but did not produce highly marbled beef. Key words: Beef cattle, carcass, growth, intramuscular fat, marbling

Mapping quantitative trait loci for body weight on the X chromosome in mice. I. Analysis of a reciprocal F2 population

Evidence of a large sex-linked effect accounting for 25% of the divergence between mouse lines selected for body weight has been described previously. A marker-based study was undertaken to determine the number and map positions of the putative X-linked quantitative trait loci (QTLs). An F2 population was generated from a reciprocal F1 between an inbred low line derived from the low selection line and the high selection line. To enable inference of marker-associated QTL effects on the X chromosome, an analytical technique was developed based on the multiple regression method of Haley and Knott. The analysis of data on 10 week weight indicated a single QTL of large effect situated at about 23 cM from the proximal end of the chromosome, with a peak LOD score of 24.4. The likelihood curve showed a single well-defined peak, and gave a 95% confidence interval for the QTL location of 8 cM. The estimates for the additive genotypic effects in males and females (half the differences between hemizygous males and between homozygous females) were 2.6 g in both cases, or 17% and 20% of the 10 week body weight in males and females respectively. Dominance effects in the females were found to be non-significant. No significant X-linked effect on carcass fat percentage was detected, but a single X-linked QTL appears to explain almost the entire X-linked body weight effect.

Predicting carcass composition and individual feed requirement in live cattle widely varying in body size.

A total of 192 feeder steers of five breed types and body sizes commonly found in the United States cattle population were fed high-energy diets to three endpoints (275-, 300-, and 360-kg carcass weights) to determine their carcass composition. Before slaughter, ultrasound was used to predict fat thickness, longissimus muscle area, and marbling. Individual steer data were used for developing prediction equations, which were validated with three independent data sets. These data were used to develop and validate equations to predict carcass composition and DM requirements for individuals fed in pens and varying in breed type, body weight and size, and ADG. Equations to predict carcass weight during growth accounted for 84, 83, and 88% of the variation in the three data sets with 0, 1, and 3% bias. An equation to predict percentage of carcass fat from fat thickness and equivalent shrunk weight accounted for 96% of the variation in the percentage of carcass fat. An equation to predict yield grade from longissimus muscle area per 100 kg, fat thickness, and equivalent shrunk weight accounted for 93% of the variation. Dry matter requirement predicted by the system for individuals accounted for 48% of the variation in actual DMI with a 3% overprediction bias. The equations allow the user to allocate feed to individual animals in group-feeding environments along with marketing cattle on an individual basis at optimum endpoints given cattle types, feeding costs, and market prices.

Virginiamycin and Caloric Density Effects on Live Performance, Blood Serum Metabolite Concentration, and Carcass Composition of Broilers Reared in Thermoneutral and Cycling Ambient Temperatures

One experiment utilizing Cobb × Cobb male broilers was conducted to evaluate virginiamycin (VM; 0, 15, 20 ppm) and diet caloric density (CD; 2,945, 3,200 AMEn/kg) effects on broiler live performance, blood serum metabolites, and carcass composition. The starter period exposed birds to recommended brooding conditions, whereas from 3 to 7 wk birds were exposed to thermoneutral (TN, 24 C) or cycling temperature (CT, 24 to 35 C) environments (E). During the 21-d starter period, VM levels and high CD increased (P < 0.05) BW gain (G) and gain:feed (G:F) improved (P < 0.05) with 20 ppm VM and high CD. During 3 to 7 wk, CT reduced (P < 0.05) most live performance and carcass variables as well as heat production (HP) and energetic efficiency whereas energy content per gram of tissue increased. The main effect of VM and CD on blood serum constituents was not significant; however, CT decreased (P < 0.05) serum Na, K, Ca, Mg, Fe, albumin, and total protein. Within CT, G increased (P < 0.05) with high CD and with the 15 ppm VM combination, whereas within TN, G was unaffected by CD, but increased (P < 0.05) with the 20 ppm VM and low CD combination compared with the control. High CD increased (P < 0.05) BW, G, carcass weight, dressing percentage, carcass percentage fat, carcass dry matter, carcass energy content per bird, HP, fat, and protein gain but reduced (P < 0.05) carcass percentage protein and energetic efficiency. Carcass weight, breast yield, fat, and protein gains as well as dry matter carcass energy content increased (P < 0.05) with VM compared with controls. The reduced (P < 0.05) calorie intake and HP with concomitant increase (P < 0.05) in calorie gain with 20 ppm VM increased (P < 0.05) caloric efficiency. In summary, the results suggest that VM improves bird performance by reducing HP and that reduced HP during high CT improves body temperature homeostasis.

Prediction of carcass composition in the rabbit

Carcass composition of two synthetic rabbit breeds was predicted from retail cuts and external measurements by using regression equations. Breed R has a higher adult weight and reaches slaughter weight 1 week before breed V. Sixty rabbits of each breed were slaughtered when they (approximately) reached the Spanish commercial liveweight of 2kg. The carcasses were measured and retailed according to the norms of the World Rabbit Scientific Association. Rabbit carcass composition is well defined by meat percentage of the commercial carcass and ratio meat bone . External measurements on the carcass, retail cuts and meat of retail cuts or muscular masses are all bad predictors of carcass meat percentage or ratio meat bone ( R 2 < 0.53). The ratio meat bone of the hind leg can give reasonable predictions for carcass meat percentage and meat bone ratio ( R 2 = 0.60 and 0.69). Dissectible carcass fat weight and dissectible carcass fat percentage can be predicted by the perirenal fat weight ( R 2 = 0.77 and 0.69). Fat depots had a low predictive power for fat percentage of the dissected meat in the half carcass.

Relative carcass value of Simmental, Holstein and their crosses based on veal calves, fattening bulls and culled cows in Switzerland

Abstract Retail carcass values of Simmental, Holstein Friesians and their crosses were determined using full dissection of the left carcass side. Alternative dairy by dual purpose breed crosses were fattened on contract farms (calves and bulls) or sampled from commercial abattoirs (cows). The carcass fat percentages of the different genotypes were not significantly different within calves, bulls and young cows. For older cows, fat percentages were standardized to 7.5%. The carcass values significantly decreased with increasing Holstein Friesian gene percentage within all categories. The decrease in the deviations per kg of cold carcass weight from pure Simmental to Black and White Holsteins amounts to 3.81% in calves, 4.38% in bulls, 21.87% in young cows and 8.54% in old cows. Prediction equations for carcass values across genotypes were best using lean percentage and premium cut percentage. It was concluded that pricing systems should focus on these traits.

Genetic and nutritional effects on the fatty acid composition of subcutaneous and intramuscular lipids of steers

Genetic and nutritional influences on fatty acid composition of subcutaneous (SNL) and intramuscular neutral lipids (IMNL) and intramuscular phospholipids (IMPL) of steer carcasses were investigated by removing the effect of carcass fat percentage (CFP) or slaughter age (SA) on the fatty acid composition. To investigate the genetic influences, steer progenies from two dam breed-types (Japanese Black (JB) and f 1 between JB bull and Holstein cows) and three different maturing types of JB sires were used. Dam breed-type did not affect any of the fatty acids except 17:0 in SNL and none of those in IMNL. Percentages of 16:0, 16:1, 18:2, SFA, MUFA and PUFA in SNL differed among sires of JB dam breed-type group ( p < 0.05) even after removing the effect of CFP. Studies on the effects of two nutritional planes [high(H) and medium-high(MH)] on the fatty acid composition of SNL, IMNL and IMPL were done using JB steers. The SNL and IMNL of the H plane steers contained greater percentages of saturated fatty acids at the same CFP but less at the same SA than the MH plane animals. The reverse was true for the unsaturated fatty acid contents.

Effects of metaproterenol, a beta-adrenergic agonist, on feedlot performance and body composition of two fat-tailed breeds of sheep

Metaproterenol (MP) was injected subcutaneously at 0, 5 (low dose) and 10 (high dose) μg kg −1 W 0.75. Most feedlot parameters were not influenced by MP treatment. Low dose of MP increased weight of cold carcass excluding the fat-tail ( P < 0.05). Carcass moisture, ash, fat and protein percentages were not affected by MP. Mean weight of chemically determined carcass fat was higher in low dose than control lambs ( P < 0.05). Total carcass protein was higher for lambs receiving the low dose of MP for 100 days. Both low ( P < 0.05) and high ( P < 0.01) doses of MP resulted in lower dissected empty carcass fats, if MP was used for 120 days. MP did not affect Longissimus dorsi (LD) area and depth, but LD width was greater at higher dose of MP. The low dose of MP resulted in a greater subcutaneous fat (SCF) depth in Ghezel lambs at 8th rib, whereas the high dose decreased SCF in depth at 12th rib in Mehraban (breed X treatment interaction). A breed X day X treatment interaction was noted for the effect of MP on heart weight but the weights of other internal organs were unaffected by MP treatment. Weight, volume and length of fat-tail was decreased when low dose of MP was used for 100 days; however, fat-tail width was increased at high dose ( P < 0.05). Treatment of lambs for 80 days with low dose of MP decreased weight of carcass bone; however, treatment for longer periods increased amount of bone in the carcass ( P < 0.05). Hap and total carcass meat was increased in lambs receiving low dose of MP ( P < 0.05). Results indicated that the beta-adrenergic agonist MP, affected body composition of fat-tailed sheep in a manner which was dependent on breed, dose and period of treatment, as has been reported for other betaagonists in thin-tailed sheep. MP decreased fat-tail weight but increased carcass fat and protein; however, percent decrease in fat-tail weight was greater than increase in carcass fat. Further experiments are needed to determine the most suitable beta-agonist for use in fat-tailed sheep.

Effects of β-agonist, L-644,969, on adipose depots in growing female rats

Growing female Sprague Dawley rats (n = 33) were used to determine the effects of β-agonist, L-644,969, on adipose depots, mammary growth and plasma ST and IGF-I levels. Fat-cell diameter in SF and PF, and mammary DNA content were studied. Rats were allocated to three groups to receive 0,4 or 8 mg kg−1 L-644,969 in powdered diet for 35 d. Compared with control, total mammary gland weight, as a proportion of final body weight, was reduced 14.6 (P &lt; 0.05) and 35.6% (P &lt; 0.01), PF was reduced 30 and 49.6% (both P &lt; 0.01) by 4 and 8 mg kg−1, respectively. The SF was reduced 22.3% (P &lt; 0.05) by β-agonist at 8 mg kg−1 only. In all fat depots, the reductions increased with increasing dose of β-agonist. Carcass fat percentage was reduced by 28.5 and 41.7% (both P &lt; 0.01) in rats fed β-agonist at 4 and 8 ppm, respectively. Fat-cell diameter in both SF and PF was reduced (P &lt; 0.05) (except at 4 ppm level in SF), and mammary DNA content was increased (P &lt; 0.01) in both treatment groups. There was a trend to increased ST concentration but to lower IGF-I concentration as β-agonist levels in diet increased (P &gt; 0.1). The results indicate that β-agonist is effective in reducing body fat deposition and fat-cell size and stimulating mammary gland growth, which may play a role in the control of mammogenesis in growing rats. Key words: Rats, β-agonist, mammary gland, adipose tissue

The effect of choline and myo-inositol on liver and carcass fat levels in aerobically trained rats.

Choline and myo-inositol are dietary supplements ingested under the premise that they facilitate the burning of stored fat. Choline and myo-inositol have been shown to prevent abnormal or excessive liver accumulation of cholesterol and triglycerides in choline and myoinositol deficient rats. The current study was designed to determine whether the consumption of choline and myoinositol by non-deficient aerobically trained rats affects the percent liver and carcass fat. Nineteen rats were trained aerobically for ten weeks then randomly assigned to an experimental group fed choline and myo-inositol mixed with their chow, or a control group fed only chow. Rats were sacrificed after 24 more days of aerobic training. Percent carcass and liver fat were determined by a lipid extraction procedure. There was a significant difference in the percent liver fat between groups, with the experimental group having less fat (6.69 +/- 2.23 vs 9.22 +/- 2.91 percent fat; r = 0.05). Percent carcass fat was not significantly different. There was a significant difference in the amount of weight gained during the 24 days of treatment, with the experimental group gaining less weight (5.1 +/- 9.2 vs 11.8 +/- 3.1 g; r < 0.05). The lack of an effect on percent carcass fat indicates that choline plus myoinositol supplements do not reduce adipose tissue mass but can inhibit weight gain while decreasing liver fat.

Effect of Early Nutrient Restriction on Broiler Chickens.: 1. Performance and Development of the Gastrointestinal Tract

An experiment was conducted to determine the effects of early nutrient restriction on performance and development of the gastrointestinal tract of broiler chickens. Four hundred male broiler (Ross × Ross) chicks raised in floor pens were assigned to two treatment groups. One group was given ad libitum access to feed from 1 to 48 d of age. The second group was feed restricted from 7 to 14 d of age to an energy intake of 1.5 × BW.67 kcal ME/d and then given ad libitum access to feed from 14 to 48 d. Body weight and feed intake were determined weekly. At 49 d of age, birds were processed for carcass yield, abdominal fat pad measurement, and body composition analysis. Broilers were also sampled at 7, 14, 21, and 41 d of age for proventriculus, gizzard, small intestine (duodenum, jejunum, and ileum), pancreas, and liver weights and for intestinal length measurements. Total DNA, protein:DNA, and RNA:DNA ratios of livers and jejuna were determined as indexes of changes in cell size and number. Feed-restricted broilers failed to catch up to the Control birds in BW at 48 d of age but were superior (P < .01) in overall feed efficiency. No treatment effects were observed on breast meat yields or abdominal fat. Moreover, percentage carcass fat, crude protein, ash, and dry matter were not affected by restricted feeding. Body weight and weights of gastrointestinal organs were reduced (P < .01) by feed restriction at 14 d of age. Restricted feeding, however, did not decrease the relative weights of organs, except for liver. Feed restriction also resulted in a reduction (P < .01) of liver cell number and size and a decrease in jejunum cell number. All organs recovered normal weight on refeeding, and all cellular constituent ratios (e.g., RNA:DNA, RNA:protein, and protein:DNA) returned to normal by 41 d of age. Absolute and relative weights of supply organs (e.g., proventriculus, gizzard, small intestine, liver, and pancreas) were less affected by feed restriction and responded more quickly to refeeding than the whole body.

In vitro [U-14C]glucose utilization by tissues of weanling rats with lateral hypothalamic area lesions one month after lesion production.

The role of the lateral hypothalamic area (LHA) in intermediary metabolism was investigated by quantitation of [U-14C]glucose oxidation to 14CO2 and 14C incorporation into the glycogen and lipid fraction of the liver, epididymal fat pad, and diaphragm. Weanling male Sprague-Dawley rats received bilateral electrolytic lesions in the LHA (LHAL rats). Sham operated rats were either fed ad libitum (CON-ADLIB) or pair-gained to the LHAL rats (CON-PG). The experiment was terminated 1 month after lesion production. LHAL rats were significantly (SIG) lighter and shorter and ate less than CON-ADLIB; LHAL rats were also SIG shorter than CON-PG, pointing to a food intake-independent lesion effect. Both LHAL and CON-PG rats had SIG less percent carcass fat than CON-ADLIB, but there was no SIG difference between LHAL and CON-PG rats. Also, LHAL rats had a SIG higher percentage of carcass protein than both CON-ADLIB and CON-PG. Furthermore, LHAL rats incorporated SIG less glucose into liver glycogen than CON-ADLIB but SIG more into CON-PG, whereas CON-PG rats incorporated SIG less into liver glycogen than CON-ADLIB, again suggesting a food intake-independent effect. There was no difference among the groups in glucose oxidation and incorporation into lipids and glycogen in both diaphragm and epididymal fat pads and liver total lipid. However, livers of CON-PG metabolized SIG more [U-14C]glucose to CO2 than did livers of CON-ADLIB, suggesting a food intake-dependent effect. There was no difference between LHAL and CON-PG rats in this parameter.(ABSTRACT TRUNCATED AT 250 WORDS)

Silage or limit-fed grain growing diets for steers: II. Empty body and carcass composition.

The influence of energy source (silage- or grain-based) on empty body and carcass composition and adipocyte cellularity independent of rate of gain was tested. Sixty-four Angus steers were allotted to either a forage (ad libitum) or grain (limit-fed) diet for a growing phase (145 d) followed by 45, 75, or 105 d of ad libitum access to a grain-based diet. Eight steers were slaughtered initially and eight from each treatment were slaughtered at the end of the growing phase, and at each of the termination dates. The silage growing diet consisted (DM basis) of 55% sorghum silage (approximately 24% dry matter), 22% alfalfa hay, 11% ground shelled corn, and 11% soybean meal. The grain-based growing diet was composed of 77% ground shelled corn, 5% soybean meal, 14% cottonseed hulls, 3% molasses, and 1% salt and mineral; it was limit-fed to produce the same rate of gain as the silage diet. No implants or ionophores were used. At the end of the growing phase, the steers fed grain were heavier and had a higher percentage of fat in the empty body (24 vs 19% fat) and the carcass (26 vs 21% fat) than did steers fed forage. Rate of gain during the growth phase was related positively to percentage of carcass fat; when corrected for fill, data for both diets fit one regression line for fat vs rate of gain. When adjusted for gain during the growing phase, fat content was not different in empty body or carcass, but internal fat was higher (P < .10) for steers fed grain. After 45 d on the finishing diet, carcass fat remained low (23%), but after 75 and 105 d, fat content reached 27%. Source of energy did not detectably affect carcass composition independent of rate of gain. Cell size of adipocytes from four adipose depots increased with time on feed but were not affected by diet during the growing phase. Lean Choice beef can be produced in only 45 d in the feedlot with medium-framed Angus cattle.

Carcass Composition and Yield of 1991 vs 1957 Broilers When Fed “Typical” 1957 and 1991 Broiler Diets

Whole carcass yield and the yield of parts (i.e., wings, saddle and legs, Pectoralis major, Pectoralis minor, breast skin, rack, abdominal fat pad, heart, and lungs), as well as whole carcass analysis for fat, moisture, and ash, were measured in the 1957 Athens-Canadian Randombred Control (ACRBC) and in the 1991 Arbor Acres (AA) feather-sexable strain, when fed “typical” 1957 and 1991 diets.Using the average of both sexes, the carcass weights of the 1991 birds on the 1991 diets were 4.4, 3.9, and 3.5 times heavier than those from the 1957 ACRBC on the 1957 diet at 43, 71, and 84 d of age, respectively. Birds fed the 1991 diets had significantly heavier carcass weights than those fed the 1957 diets. Hot carcass yield of the AA broiler (x̄ of both sexes) was approximately 6 to 7% higher at the same age than for the ACRBC. Water uptake in the carcass (following a 60-min immersion in ice water) was approximately 2 to 2.5% higher in the ACRBC than in the AA broiler. Yield of saddle and legs as a percentage of live BW was about 4% higher in the AA than in the ACRBC. Dietary regimen did not affect the yield of saddle and legs. Males had 2 to 3% more saddle and legs than the females.The yield of total breast meat for the AA was approximately 3% higher (x̄ = 16.9%) than for the ACRBC over both sexes and all ages. Breast yield on the 1991 diets was approximately 1.2% higher for the AA than for the ACRBC. Females had slightly higher breast yield (1%) than males.The AA broiler had consistently heavier fat pads and higher percentage carcass fat at the same age and on the same diet than did the ACRBC. The percentage carcass fat was significantly higher on the 1991 vs the 1957 diet and in females vs males. The male-female difference in percentage carcass fat increased with age. Heart and lung size as a percentage of live BW were lower in the AA than in the ACRBC.

Serotonergic activity is depressed in the ventromedial hypothalamic nucleus of 12-day-old obese Zucker rats.

We previously reported lower ventromedial hypothalamic nucleus (VMN) serotonergic activity in 11-wk genetically obese vs. lean Zucker rats. To determine whether the activity was secondary to metabolic alterations associated with this established obesity (e.g., significant hyperphagia and hyperinsulinemia), we examined monoaminergic activity in various brain nuclei of 12-day lean (Fa/Fa and Fa/fa) and obese (fa/fa) rats early in the development of obesity. Obese pups had greater percent carcass fat than heterozygotes, both of which were fatter than homozygous lean rats. Obese, but not heterozygous lean, pups were hyperinsulinemic vs. Fa/Fa pups. VMN 5-hydroxy-3-indoleacetic acid levels, an index of serotonin release, were lower in obese and heterozygous than in homozygous lean pups and were not correlated with plasma insulin levels. Although monoamine differences also occurred in several other nuclei, for the most part they appeared to be unrelated to the obese genotype. We conclude that blunted VMN serotonergic activity is not secondary to the obese rat's hyperinsulinemia and may play a significant role in the development of obesity.

Breed effects and retained heterosis for growth, carcass, and meat traits in advanced generations of composite populations of beef cattle

Retained heterosis for growth, carcass, and meat traits was estimated in F3 generation castrate male progeny in three composite populations finished on two levels of dietary energy density (2.82 Mcal of ME and 3.07 Mcal of ME and 11.50% CP) and serially slaughtered at four end points at intervals of 20 to 22 d. Breed effects were evaluated in nine parental breeds (Red Poll [R], Hereford [H], Angus [A], Limousin [L], Braunvieh [B], Pinzgauer [P], Gelbvieh [G], Simmental [S], and Charolais [C] that contributed to the three composite populations (MARC I = 1/4 B, 1/4 C, 1/4 L, 1/8 H, 1/8 A; MARC II = 1/4 G, 1/4 S, 1/4 H, 1/4 A; and MARC III = 1/4 R, 1/4 P, 1/4 H, and 1/4 A). Breed effects were important (P < .01) for carcass weight, dressing percentage, fat thickness, and marbling score; for retail product, fat trim and bone percentages and weights at two levels of fat trim (8 and 0 mm); and for carcass lean, fat, and bone percentages and weights. Mean slaughter weight was 54.7 kg greater for the Simmental, Gelbvieh, and Charolais breeds than for the Limousin but did not differ (P > .05) from Limousin in retail product weight or carcass lean weight because of higher dressing percentage, lower fat trim percentage, and lower bone percentage of Limousin. The effects of dietary energy density were important (P < .01) for most traits. The interaction of breed group x dietary energy density generally was not important. Retained heterosis generally was significant for each composite population for weight of retail product, fat trim, bone, and carcass lean, fat, and bone. For percentage of retail product, fat trim, carcass lean, carcass fat, and chemical fat in the 9-10-11th rib cut, generally, heterosis was significant for composites MARC II and MARC III but not for composite MARC I (i.e., composites MARC II and MARC III had a lower percentage of retail product and carcass lean and a higher percentage of fat trim, carcass fat, and chemical fat in the 9-10-11th rib cut than the mean of contributing purebreds).