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PubMed1990

Influence of gestation energy level on the production of Large White x Landrace sows.

Sixty-four Large White x Landrace primiparous sows were utilized to evaluate the influence of feeding 6 vs 9 Mcal ME/d during gestation on reproductive performance. The sows remained on their respective gestation diets for four parities if they successfully farrowed, rebred and conceived. Sows fed 9 Mcal ME/d gained more weight (P less than .05) through the gestation period during parities 1 and 2 and were heavier (P less than .01) on d 110 of gestation for combined parities. Lactation weight loss was greater (P less than .05) for the sows fed 9 Mcal ME/d, resulting in similar weights at weaning. Ultrasonic backfat measurements were greater (P less than .01) on d 110 of gestation for sows fed 9 Mcal ME/d during parity 1 and remained higher (P less than .01) through the fourth-parity gestation. Although sow weaning weights were similar, sows receiving 6 Mcal ME/d scanned less backfat thickness. Gestation treatment significantly affected consumption of a common lactation diet provided ad libitum. Sows fed 6 Mcal ME/d during gestation consumed an average of 22 kg more feed (P less than .01) during lactation than those sows receiving 9 Mcal ME/d. Litter performance as measured by number and weights of pigs born alive and weaned was not altered (P greater than .10) by gestation energy intake. Days to return to estrus and the number of sows remaining in the study for four parities were similar (P greater than .10) between the two treatment groups. The number of farrowings for the four parities totaled 164, with 83 and 81 farrowings for the sows fed 6 and 9 Mcal ME/d, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

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PubMed1991

Population parameter estimates for performance and reproductive traits in Polish Large White nucleus herds.

Performance test records from on-farm tests of young Polish Large White boars and reproductive records of Polish Large White sows from 94 nucleus farms during 1978 to 1987 were used to estimate population parameters for the measured traits. The number of boar performance records after editing was 114,347 from 3,932 sires, 21,543 dams, 44,493 litters and 1,075 herd-year-seasons. Reproductive performance records of sows involved 41,080 litters from 2,348 sires, 18,683 dams and 1,520 herd-year-seasons. Both data sets were analyzed by using restricted maximum-likelihood programs. The model used for the performance records included fixed herd-year-seasons, random sires, dams and error effects, and covariances for the year of birth of sire and year of birth of dam. The model used for the reproduction data set was the same as the performance data with parity as an additional fixed effect. Estimated heritabilities were .27, .29, .26, .07, .06, .06 for average daily gain standardized to 180 d (ADG), backfat thickness standardized to 110 kg BW (BF), days to 110 kg (DAYS), litter size at birth born alive (NBA), litter size at 21 d (N21) and litter weight at 21 d (W21), respectively. Estimated common environmental effects for the same traits were .09, .10, .09, .06, .07 and .08, respectively. Genetic correlations were .25 (ADG and BF), -.99 (ADG and DAYS), -.21 (BF and DAYS), .91 (NBA and N21), .68 (NBA and W21) and .80 (N21 and W21). The respective phenotypic correlations were .23, -.99, -.20, .88, .75, .86. These population parameters for Polish Large White pigs are similar to those for breeds in other countries.

Animals↗
PubMed1991

Growth and carcass characteristics of lambs passively immunized with antibodies developed against ovine adipocyte plasma membranes.

Polyclonal antisera were collected from a mare immunized with ovine adipocyte plasma membranes. Ten crossbred wether lambs received three consecutive daily intraperitoneal injections of horse antisheep adipocyte plasma membrane immunoglobulin (ASIg) or nonimmune serum immunoglobulin (NSIg). Each injection delivered 1.5 ml serum Ig protein equivalent to either 53.4 mg ASIg or 51.1 mg NSIg per kilogram of live body weight. Lambs were housed in individual metabolic crates during the 28-d experiment and given ad libitum access to a pelleted, high-concentrate diet. Daily feed consumption was monitored individually over the experimental period and N retention was determined. Blood was collected on d 0, 4, 7, 14 and 28 for determination of nonesterified fatty acid (NEFA), triacylglycerides (TG) and hematocrit. At the conclusion of the experiment, lambs were slaughtered and carcasses were evaluated. Passive immunization against sheep adipocyte plasma membrane reduced (P less than .05) perirenal adipose tissue weight and decreased ether extract content of both subcutaneous and perirenal fat. Treatment tended to reduce average backfat thickness (24%) and estimated kidney pelvic fat (16%). Treatment with ASIg reduced (P less than .05) blood plasma NEFA but did not alter blood TG or hematocrit values. Average daily weight gain was lower (P less than .01) in the ASIg-treated group. However, the efficiency of carcass production, measured as carcass weight, was not affected by ASIg treatment.

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PubMed1991

Interactive effects of sodium zeolite-A and copper in growing swine: growth, and bone and tissue mineral concentrations.

An experiment was conducted with 64 crossbred pigs to determine the effect of 0 or .50% dietary sodium zeolite-A (NZA) in combination with 0 or 250 ppm supplemental Cu (as CuSO4.5H2O). Pigs were assigned randomly to one of the following four treatments: 1) corn-soybean meal basal (B), 2) B + .50% NZA, 3) B + 250 ppm Cu, or 4) B + .50% NZA + 250 ppm Cu. Each treatment was replicated four times with four pigs per replicate. Average initial weight was 7.5 kg and the experimental period lasted 144 d. Overall rate and efficiency of gain, incidence of gastric ulcers, dressing percentage, carcass weight, percentage of muscling, 10th rib fat, loin eye area, blood urea N, and bone Ca, P, Mn, Fe, Ni, Na, and Al concentrations were not affected by treatment. The addition of 250 ppm Cu increased liver (P less than .01), serum (P less than .06), and bone (P less than .07) Cu concentrations but decreased mean backfat thickness (P less than .09), bone ash percentage (P less than .03) and serum (P less than .09) and bone (P less than .01) Zn concentrations. Sodium zeolite-A increased serum alkaline phosphatase (P less than .04), carcass length (P less than .06), and liver (P less than .02) and bone (P less than .01) Zn content but decreased (P less than .04) serum Ca and serum inorganic P concentrations. Sodium zeolite-A did not protect against liver Cu accumulation or gastric ulceration in growing swine fed 250 ppm supplemental Cu.

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PubMed1991

Effects of pre- and postpubertal feeding on production traits at first and second estrus in gilts.

The effects of feeding level on body weight (BW), lifetime growth rate, backfat thickness (BF), fatness (BF/BW) and ovulation rate at first (puberty) and second estrus were examined in 145 gilts. From 47.2 kg until puberty, gilts were fed 2.0 kg/d (L) or had ad libitum access to feed (H). From puberty to second estrus, the feed allowance of one-half of the L gilts was increased to 2.8 kg/d. Flush-feeding only normalized ovulation rate (OR) to that observed in gilts with ad libitum access to feed. At puberty, a quadratic negative relationship between lifetime growth rate and age indicated that age at puberty was minimum at a growth rate of less than or equal to .60 kg/d. Thereafter, age at puberty became independent of, or possibly positively related to, lifetime growth rate. Gilts with higher lifetime growth rate also were heavier and fatter at puberty. It was concluded that puberty may have been attained when a certain BF or fatness was achieved, because growth rate of restricted-fed gilts and quickly growing gilts with ad libitum access to feed may have been associated with reduced fat deposition. Hence, maximizing growth rate in replacement gilts does not hasten the attainment of puberty. Growth rate may be manipulated by feed restriction, in order to attain a target BW at boar stimulation (approximately 90 kg), which would coincide with a minimum age (approximately 155 d) and BW at puberty (approximately 97 kg). Nutritional flushing during the first estrous cycle then could be used to normalize OR at mating at second estrus of gilts that were restricted-fed when prepubertal.

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PubMed1991

Effects of ractopamine, genotype, and growth phase on finishing performance and carcass value in swine: I. Growth performance and carcass merit.

A replicated factorial experiment using 183 individually fed crossbred barrows was conducted. Pigs were fed an 18.5% CP (.95% lysine) diet with 3,594 kcal of ME/kg. The effects of five genotypes (GT): 1) Hampshire (H) x (H x Duroc [D]), 2) synthetic terminal sire line, 3) (H x D) x (Landrace [L] x [Yorkshire (Y) x D]), 4) L x (Y x D), and 5) Y x L; two levels of ractopamine (RAC) treatment: 0 and 20 ppm; and three treatment weight periods (WT): 1) 59 to 100, 2) 73 to 114, and 3) 86 to 127 kg live weight on growth performance and carcass traits were evaluated. Ractopamine increased (P less than .0001) amount (FSL) and percentage (PFSL) of carcass lean standardized to 10% fat content, loin eye area (LEA), and dressing percentage (PDRES) and reduced (P less than .01) amount (DF) and percentage (PDF) of dissected fat. Magnitudes of RAC effects were smaller than those reported by other researchers. Effects of GT and WT on all growth and carcass traits were highly significant (P less than .001) except for those of WT on ADG (P less than .05) and GT on average feed intake (AFI) and backfat thickness at the last rib (BFLR; P less than .05). Genotype 3 performed better for most economically important traits than did GT 1 and 4, suggesting that heterosis existed in GT 3, which essentially was obtained by crossing GT 1 and 4. Among the three treatment periods, WT 2 had the highest ADG. As BW increased from WT 1 to 3, AFI and AFI/ADG ratio (FCR) increased and lean percentage decreased.(ABSTRACT TRUNCATED AT 250 WORDS)

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PubMed1991

The effect of ractopamine hydrochloride on the carcass cutting yields of finishing swine.

This study was designed to evaluate growth performance, carcass cutting yield, and processing characteristics of boneless hams and bellies from finishing pigs fed diets containing 0, 5, 10, or 20 ppm of the phenethanolamine ractopamine hydrochloride (RAC). Sixty pigs were blocked by starting weight and randomly assigned to pens (four pigs/pen) within each of three blocks. Treatments were then randomly assigned to the pens to total six pens of the 0-ppm level and three pens each at the 5-, 10-, and 20-ppm RAC levels. Weight gain and feed consumption were monitored and animals were slaughtered by weight block after approximately 48 d on trial. Slaughter weight, ADG, and feed/gain were improved (P less than .05) for RAC treatments. Dressing percentage was higher and increased linearly (P less than .05) for RAC treatments. Carcass weight, length, leaf fat weight, backfat thickness, loin eye area, and color, marbling, and firmness of the longissimus were evaluated. The RAC-treated carcasses were heavier (P less than .05) and loin eye area increased linearly (P less than .05). One side of each carcass was fabricated using National Association of Meat Purveyors specifications. Trimmed hams and loins from the RAC treatments were heavier (P less than .05) than those from control animals. No differences (P greater than .05) in carcass cutting yield (percentage of trimmed primal cuts) were observed between treatments. However, trimmed hams and loins from the 20-ppm RAC treatment represented a greater (P less than .05) percentage of carcass weight than did those from control animals. Ractopamine did not affect raw belly or bacon characteristics (P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)

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PubMed1991

Effects of exogenous porcine somatotropin (pST) administration on growth performance, carcass traits, and pork meat quality of Meishan, Pietrain, and crossbred gilts.

Seventeen to twenty-three females of lean (Pietrain, PI), fat (Meishan, MS), or intermediate genotype (PI x [3/4 Large White x 1/4 MS]), referred to as crossbred (CR), were injected between 60 and 100 kg live weight with 6 mg/d of porcine somatotropin (pST) and compared to similar numbers of control females receiving the vehicle only. Average daily gain increased similarly in the three genotypes (125 g/d). Feed conversion ratio tended to decrease to a higher extent in MS (-2.0 kg of feed/kg of gain) than in the other two genotypes (-1.1 and -.9 kg of feed/kg of gain for CR and PI, respectively). A significant genotype x treatment interaction was also observed for backfat thickness (BF) and fat, muscle, and bone development. Effects of pST in PI, CR, and MS pigs were, respectively, -6.2, -9.6, and -16.1 mm for BF and 3.0, 6.8, and 11.8% carcass muscle. The influence of pST on physical measurements of meat quality was rather low, although desirable effects (P less than .05) were obtained on the reflectance and water-holding capacity of PI and CR. Intramuscular fat content was reduced by approximately 1% in MS and CR but not in PI. The metatarsals of pST-treated animals had a higher water content (except in PI), a lower mineralization, and a lower breaking strength (except in MS). The existence of breed variations in the response to pST might result in changes of the relative merit of crossbreeding schemes.

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PubMed1992

Effect of feed intake during late development on pubertal onset and resulting body composition in crossbred gilts.

A total of 105 nonboar-exposed, F2 ([Landrace x Yorkshire] x Duroc) gilts were used in two replicates of a randomized complete block experiment to evaluate the effect of dietary feed intake on pubertal onset and subsequent body composition. Feed intakes were established at 50% of ad libitum (AL-50), 75% of ad libitum (AL-75), or at ad libitum (AL-100) levels from 4.5 to 9 mo of age. A corn-soybean meal diet fed to all gilts was formulated to meet or exceed nutrient requirements except for energy. Puberty was measured by two methods: 1) monitored once daily by back pressure applied by the herdsman or 2) from elevated plasma progesterone concentrations. Body composition was evaluated by the deuterium oxide method after plasma progesterone concentrations were elevated. Daily feed intake for the experimental period averaged 1.6, 2.3, and 3.2 kg, and the BW of gilts at 8 mo of age were 111, 131, and 154 kg for the AL-50, AL-75, and AL-100 groups, respectively. Body weight, backfat thickness, and body fat content increased linearly (P < .01) as feed intake increased, but age at puberty was not severely influenced. A minimum body fat content or percentage did not seem to initiate pubertal onset. There was a trend for a lower percentage of the AL-50 gilts to ovulate (P = .08) than those fed the AL-75 and AL-100 intakes. An inverse relationship resulted between the percentage of gilts that ovulated to the percentage that showed behavioral estrus.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

The repeatability and accuracy of ultrasound in measuring backfat of cattle.

Repeatability of ultrasound backfat measurements was determined on 217 cattle, and the association of ultrasound and carcass backfat measurements was evaluated with 580 animals. The correlation (repeatability) between consecutive ultrasound measurements was .975. Average difference between two ultrasound measures was .72 mm and error size was directly related (P less than .001) to the amount of backfat. Ultrasound measures averaged 8% (P less than .001) less than carcass measures. The average absolute difference between these two measures was 1.57 mm. Discrepancies were (P less than .001) larger when backfat was thicker; cattle with backfat measuring less than 10 mm averaged 1.43 mm absolute difference, whereas those with backfat greater than 10 mm averaged 1.89 mm. The variance of the discrepancies was partitioned into three components: ultrasound measurement error (14%), drift related to intercept and slope (15%), and residual (71%). The residual component may have represented errors in carcass measurement. In a subsequent trial with 175 cattle, average difference between ultrasound and carcass backfat measurements was reduced to 1.19 mm. Also, the slope and intercept virtually mimicked the isopach. Ultrasound measures can be more precise (minutely exact) and accurate (close to the true value) than carcass measures for assessing absolute backfat thickness in cattle. Elements of measurement protocol that may improve ultrasound technique are imparted in the manuscript.

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PubMed1992

Performance and carcass characteristics of swine when fed diets containing canola oil and added copper to alter the unsaturated:saturated ratio of pork fat.

A 3 x 2 trial was conducted to determine the effects of adding canola oil (0, 5, or 10%) and copper sulfate (0 or 250 ppm Cu) to diets of growing-finishing swine on performance, carcass characteristics, and carcass fat fatty acid composition. The trial used 180 pigs (27 kg). Grower diets (.80% lysine for 0% canola oil diet) were given from 27 to 57 kg of BW and finisher diets (.64% lysine) from 57 to 102 kg. Diets were formulated to constant ME:lysine ratio within the grower and finisher phases. Over the entire growing-finishing period, the addition of canola oil to the diets resulted in linear improvements in rate of gain (P less than .05) and feed efficiency (P less than .01). Dietary additions of canola oil had no effect (P greater than .10) on resulting backfat thickness or longissimus muscle area but resulted in reductions (P less than .01) in loin marbling and color and carcass fat firmness, mostly noted in pigs fed the diets with 10% canola oil. Canola oil additions at 5 and 10% levels, respectively, resulted in a 23 and 37% reduction (P less than .01) in saturated fatty acids, 3 and 8% increase (P less than .01) in monounsaturated fatty acids, and 37 and 77% increase (P less than .01) in polyunsaturated fatty acids in the carcass fat compared with the diets without canola oil. The addition of canola oil to diets of growing-finishing swine had a favorable influence on animal performance and on increasing the unsaturated:saturated ratio of the carcass fat.(ABSTRACT TRUNCATED AT 250 WORDS)

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PubMed1992

Effects of Duroc, Meishan, Fengjing, and Minzhu boars on productivity of mates and growth of first-cross progeny.

Meishan, Fengjing, Minzhu, and Duroc boars were mated by AI to crossbred gilts to compare the sire breeds for effects on productivity of their mates and performance of their progeny. Gilts were derived from a four-way cross of Chester White, Landrace, Large White, and Yorkshire. At weaning, litters sired by Meishan boars averaged 1.69 and 1.32 more pigs than those sired by Duroc and Minzhu boars, respectively (P less than .05). Pigs sired by Meishan and Fengjing boars averaged 1.2 to 1.8 more nipples than pigs sired by Duroc and Minzhu boars (P less than .05). Minzhu-sired pigs had a lower (P less than .05) survival rate to 14 and 28 d of age than did those sired by Meishan, Fengjing, and Duroc. Fengjing-sired pigs were heavier than Minzhu-sired pigs at birth and heavier than Minzhu- and Duroc-sired pigs at 14, 28, and 56 d of age (P less than .05). At 70 d of age, Meishan-sired pigs were heaviest, followed in order by Fengjing-, Duroc-, and Minzhu-sired pigs. At 98 d of age, Meishan-sired pigs were significantly heavier than all other breed groups and Duroc-sired pigs were significantly heavier than Minzhu-sired pigs. At 126 and 154 d of age, Duroc-sired pigs were heaviest, followed in order by Meishan-, Fengjing-, and Minzhu-sired pigs; all differences were significant. Average backfat thickness of gilts at 99.7 kg was least for Duroc-sired gilts and highest for Meishan-sired gilts. Sire breed groups did not differ significantly in feed efficiency from 70 to 98 d of age. Duroc-sired pigs were the most efficient (P less than .05) from 98 to 126 and 126 to 154 d of age. Results indicate that use of these Chinese breeds in crossbreeding programs will decrease performance traits. This decrease would have to be offset by increases in reproductive efficiency of Chinese sows, use of repartitioning agents, or other management techniques if Chinese pigs are to improve overall production efficiency of a crossbreeding program.

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PubMed1992

Prediction of performance of progeny from test station boars.

Data were obtained from 1,954 Duroc and 2,252 Yorkshire purebred and crossbred progeny sired by 34 Duroc and 32 Yorkshire boars, respectively. Boars were purchased from the North Carolina Swine Evaluation Station during August 1983 to December 1988. Boars were selected to represent high and low indexes at the test station. Progeny were raised and tested under conditions similar to commercial pig production at the Tidewater Research Station. For each breed of boar (Duroc and Yorkshire), breed type (purebred and crossbred), and sex (castrates and gilts) of progeny, regression coefficients of progeny traits on each sire trait were computed. Progeny traits were ADG, days to 104.3 kg BW (DAYS), backfat thickness (BF), and feed conversion ratio (FC). Sire traits were ADG, DAYS, BF, FC, and INDEX. Effects of boar test group and progeny test group were included in the models. Averaged over breed type and sex, a 25-unit (1 SD) increase in sire INDEX resulted in 14.5 g more ADG, 3.2 fewer DAYS, .57 mm more BF, and .017 lower FC in Durocs and 5.6 g more ADG, .01 more DAYS, .81 mm less BF, and .083 lower FC in Yorkshires. The low magnitude and variable signs of some regression coefficients suggested that predictions of progeny performance from performance of individual sires at the North Carolina Swine Evaluation Station were not very reliable. Differences between regressions for purebreds and crossbreds implied small correlations between the two breed types. Differences between Durocs and Yorkshires indicated that genetic parameters might not be the same for the two breeds.

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PubMed1992

Genetic analyses of growth, real-time ultrasound, carcass, and pork quality traits in Duroc and Landrace pigs: II. Heritabilities and correlations.

Knowledge of the genetic control of pork quality traits and relationships among pork quality, growth, and carcass characteristics is required for American swine populations. Data from a 2 x 2 diallel mating system involving Landrace and Duroc pigs were used to estimate heritabilities and genetic correlations among growth (ADG), real-time ultrasonic (US) measures of backfat thickness (BF) and longissimus muscle area (LMA), carcass characteristics, and various pork quality traits. Data were collected from 5,649 pigs, 960 carcasses, and 792 loin chops representing 65, 49, and 49 sires, respectively. Genetic parameters were estimated by REML assuming animal models. Heritability estimates were moderate to high for ADG, USBF, USLMA, carcass BF, and LMA, percentage of LM lipid (IMF), pork tenderness, and overall acceptability. Estimates were low to moderate for percentage of cooking loss, pH, shear force, percentage of LM water, water-holding capacity (WHC), pork flavor, and juiciness. Genetic correlations between US and carcass measures of BF and LMA indicate that selection based on US data will result in effective improvement in carcass characteristics. Selection for increased LMA and(or) decreased BF using US is, however, expected to result in decreased IMF and WHC, increased percentage of LM water and shear value, and in decreased juiciness, tenderness, and pork flavor. Average daily gain was favorably correlated with IMF and unfavorably correlated with shear force. Selection for increased ADG is expected to improve WHC but to decrease the percentage of LM water, with an associated decrease in juiciness. The results of this study suggest the feasibility of including meat quality in selection objectives to improve product quality. Favorable genetic correlations between IMF and eating quality traits suggest the possible merit of including IMF in the selection objective to improve, or restrict change in, pork eating quality.

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PubMed1993

Divergent selection for postweaning feed conversion in Angus beef cattle: III. Linear body measurements of progeny.

Postweaning performance data were obtained on 401 group-fed, purebred Angus calves from 24 selected sires (12 high- and 12 low-feed-conversion sires) from 1983 through 1986 at the Northwestern Branch of the Ohio Agricultural Research and Development Center. Body measurements of progeny were taken from 1983 through 1986 for hip height and backfat, whereas others, except chest measurements (depth and width) that were available only in 1985, were taken from 183 progeny born in 1985 and 1986. The objective of this portion of the study was to determine whether differences in linear body measurements exist between progeny of high- and low-feed-conversion sires. Differences between progeny of high- and low-feed-conversion sires tended to exist (P < .10) for heart girth (176.3 +/- 1.2 vs 173.2 +/- 1.2 cm) and were significant for backfat thickness (.94 +/- .01 vs .87 +/- .02 cm). No significant differences were observed for hip height (115.3 +/- .5 vs 115.5 +/- .5 cm), chest depth (58.8 +/- .6 vs 57.4 +/- .6 cm), chest width (44.4 +/- .5 vs 44.0 +/- .5 cm), head width (21.2 +/- .2 vs 21.1 +/- .2 cm), head length (42.4 +/- .3 vs 41.6 +/- .3 cm), muzzle circumference (41.0 +/- .4 vs 41.6 +/- .3 cm), length between hooks and pins (46.7 +/- .5 vs 46.2 +/- .5 cm), length between shoulder and hooks (94.9 +/- 1.0 vs 93.1 +/- 1.0 cm), or volume (361,199 +/- 4,885 vs 352,718 +/- 5,026 cm3).

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PubMed1993

Evaluation of Australian merino and U.S. sheep breeds for growth and carcass traits.

One hundred twenty 4-mo-old wether lambs born to Targhee ewes and sired by six rams each from Merino (Finewool, FM and Strongwool, SM), Rambouillet (Dubois, DR and Texas, TR), and Targhee (T) breeds were randomly assigned to predetermined slaughter weight groups of 43, 48, 52, and 57 kg and evaluated for growth and carcass traits. Overall mean ADG and feed conversion rate (FC, kilograms of feed/kilogram of gain) were .28 and 6.4 kg, respectively; T grew the fastest (.31 kg) and FM grew the slowest (.23 kg). Targhee and SM had the best FC (6.2), whereas FM (6.8) had the poorest FC (P < .05). Overall mean backfat thickness (BT) and carcass fat (CF) were 4.8 mm and 25.6%, respectively. Targhee had the lowest (24%) and FM the highest (27.8%) CF percentage (P < .05). Differences (P < .05) were observed for BT and CF among slaughter weight groups; overall means for both traits gradually increased from the 43- to the 57-kg groups. Separate analysis of the 43- and the 48-kg groups indicated nonsignificant breed differences for feed traits, whereas significant differences still existed for CF. It was concluded that Merino strains grew more slowly, were less efficient in postweaning growth, and had higher carcass fat content than U.S. breeds at a constant slaughter weight; SM were more comparable to U.S. breeds than were FM. Merino-cross lambs should be slaughtered at lighter BW to avoid excessive carcass fat.

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PubMed1993

Body composition of postpubertal gilts at nutritionally induced anestrus.

An experiment using comparative slaughter was conducted to examine the relationship between occurrence of nutritionally induced anestrus in postpubertal gilts and chemically determined body composition and body composition changes. Thirty-nine Duroc x (Yorkshire x Landrace) gilts, each having experienced three or more estrous cycles, were used. Nine gilts were chosen randomly, weighed, ultrasonically scanned for 10th rib backfat thickness, and slaughtered to determine initial body composition. Remaining gilts were allotted randomly to five dietary treatments, four characterized as severely energy restrictive (RES; .25, .50, .75, and 1.0 mcal of ME/d) and a control (3.4 Mcal of ME/d). Dietary treatments provided equal amounts of protein (50 g), minerals, and vitamins daily. Individual serum progesterone levels were determined every 3 d using RIA and gilts were considered anestrous when concentrations were < 1.0 ng/mL for four consecutive samples (9 d). All RES gilts became anestrous, and gilts restricted more severely tended (P = .22) to do so more quickly. Days to anestrus were 66.0 +/- 12.0, 77.4 +/- 13.1, 84.5 +/- 12.0, and 86.5 +/- 12.0 for treatments .25, .50, .75, and 1.0, respectively. Among RES treatments there were no linear, quadratic, or cubic effects of ME intake (P > .10) on the quantity of body protein or fat lost, or on the quantity of body protein or fat remaining at anestrus. However, individual body protein and body fat contents of RES gilts at slaughter revealed that anestrus occurred at a wide range of body compositions, from 13.4 to 20.2 kg of protein and .36 to 27.0 kg of fat. This wide range of individual values suggests that estrous activity in the mature gilt is not controlled by specific threshold levels of body reserves.

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PubMed1993

Interrelationships between porcine somatotropin and dietary lysine on growth performance and carcass characteristics of finishing swine.

Seventy-two barrows (initial weight = 57.1 kg) were used to determine the interrelationship between porcine somatotropin (pST) and dietary lysine and their effects on growth performance and carcass characteristics. Pigs were injected daily in the extensor muscle of the neck with either 4 or 8 mg of pST and fed a pelleted corn-soybean meal-sesame meal diet (.8% lysine; 17.8% CP) or diets containing 1.0, 1.2, or 1.4% lysine provided by additions of L-lysine.HCl (2 x 4 factorial arrangement). Control pigs (placebo injection) received the .8% lysine diet. All diets were formulated to contain > or = 200% of current recommendations for other amino acids, vitamins, and minerals. A tendency for a pST x lysine interaction was observed for cumulative ADG (P < .15) and feed conversion (G/F; P < .05). Average daily gain and G/F were improved by increasing dietary lysine level in pigs injected with 4 mg/d of pST; however, pigs injected with 8 mg/d of pST had greater improvements in cumulative ADG and G/F with added lysine. Feed intake was reduced (quadratic, P < .10) as dietary lysine level and pST dosage increased. Increasing pST dosage and dietary lysine increased (linear, P < .05) longissimus muscle area and decreased backfat thickness. Trimmed ham and loin weights were increased (linear, P < .10) by pST dosage. Chemical composition of samples taken from the loin, ham, and belly indicated increased moisture and CP and decreased lipid content as pST dosage and dietary lysine level increased (quadratic, P < .05). Shear force values from loin and semimembranosus increased with increasing lysine level (quadratic, P < .01) and pST dosage (linear, P < .05); however, these differences were not detected by sensory analysis (P > .20). Plasma urea concentrations on d 28 decreased with increasing lysine level (quadratic, P < .05), and plasma lysine concentrations increased (linear, P < .01). Based on the pST x lysine interaction for ADG and G/F, these data suggest that the lysine level needed to maximize growth performance and carcass characteristics may be proportional to the pST dosage provided. Growth and carcass characteristics were maximized by dietary lysine intakes of 27 to 32 and > or = 36 g/d for pigs injected with 4 and 8 of mg/d of pST, respectively.

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