Male BW Research Articles

Effects of an In Ovo Injection of an Anti-Androgen on Embryonic and Posthatching Growth of Broiler Chicks

Experiments were conducted to determine whether in ovo injection of Flutamide®, a non-steroidal anti-androgen, would affect posthatching growth of broiler chickens. Before doing these studies it was necessary to develop a bioassay to demonstrate that Flutamide® had anti-androgenic actions when injected in ovo. In ovo injection of 0.06 to 1.74 μmol of testosterone propionate (TP) per egg on the 8th d of incubation caused a dose-related decrease in weight of the bursa of Fabricius of newly hatched chicks. In subsequent experiments, 1.74 μmol of Flutamide® significantly decreased the bursal regression produced by 0.58 μmol of TP when both substances were injected on Day 8 of incubation and bursal weights were taken on the day of hatch.Having established that Flutamide® could block the effects of high doses of exogenous TP, it was reasoned that it could block the action of much lower endogenous levels. In two of the three experiments, injection of Flutamide® on the 8th d of incubation resulted in a dose-related decrease in 21- and 49-d BW of male broiler chickens. The material had no effect on BW of males in one experiment and had no effect on BW of females at any age in any of the experiments. The data suggest that interference with the actions of endogenous androgens during embryonic life suppresses the posthatching growth of male broilers.

X-linked elements associated with negative segregation distortion in the SD system of Drosophila melanogaster.

Three elements, M1, M2 and M3, found in a special X chromosome, supp-X(SD), modify the degree and direction of segregation distortion in the SD system of Drosophila melanogaster. The first element, M1, is located between the y and the cv loci, probably close to the y locus. The second element, M2, is located near the cv locus and the third element, M3, is located between the y and the car loci. The M1 element appears to cause a relatively small amount of reduction in the rate of recovery of the SD-72, but not the cn bw, chromosome from SD-72/cn bw males, when raised at 27.5 degrees. The M2 and the M3 elements cause considerable decrease in the recovery rate of the SD-72 chromosome, whereas they increase the recovery rate of the cn bw chromosome. The amount of decrease is nearly the same as the amount of increase for each element. Some type of "switch" mechanism in the directions of distortion is suggested for each of these two elements and their effects appear to be approximately additive.

Divergent Selection for Body Weight and Yolk Precursor in Coturnix coturnix japonica.: 9. Evaluation of Traits Associated with Onset of Sexual Maturity

An experiment was conducted to compare traits associated with onset of sexual maturity in Japanese quail lines. Lines divergently selected for high and low 4-wk BW (HW and LW), and high and low total plasma phosphorus at beginning of lay (HP and LP) were compared with a randombred line (RBC1) that served as the base population for HW, LW, HP, and LP. The HW sublines (HW-HP and HW-LP) and LP subline (LP-HW) were also compared to their respective line of origin. Most of the differences observed for males selected for a single trait were found for weight-selected rather than for phosphorus-selected lines. The patterns of significance closely followed differences expected due to the extreme diversity in BW for the HW and LW when compared with RBC1. Females generally matured approximately 2 wk later than males for HW, HP, and LP. Line LW females matured approximately 4 wk later than LW males. Differences were observed for variables associated with onset of sexual maturity for HW, LW, and HP when compared with RBC1. Observed changes in carcass variables for sublines were generally associated with reductions in BW for HW-HP, and HW-LP versus HW and for increases in BW for LP-HW versus LP. The differences were likely due to the fact that two-trait selection (BW for males and total plasma phosphorus in females) has allowed weights to diverge when compared with lines selected for single traits.

Temperature sensitivity of negative segregation distortion in Drosophila melanogaster.

Previous work has shown that the direction of segregation distortion in the SD (Segregation Distorter) system in Drosophila melanogaster can sometimes be reversed, but this was found only with rather weak distorters and the effect was not large. The present study reports large negative segregation distortion in a strong distorter, SD-72 chromosome. In the presence of a specific X chromosome, supp-X(SD), the proportion, k, of SD-72 chromosomes recovered from the SD-72/cn bw males ranges from 0.99 at 20 degrees to 0.11 at 28.5 degrees, whereas with a standard-X chromosome, k ranges from 0.99 to 0.95 for the same temperature range. The temperature-sensitive period is during spermiogenesis. Using a mating system in which the sperm supply is nearly exhausted, it was shown that the negative distortion at high temperatures is due to an absolute reduction in the number of SD-72 chromosomes and an absolute increase in the number of cn bw chromosomes recovered. After adjusting for non-SD-related temperature effects, the amount of decrease in the number of SD-72 progeny is nearly the same as the amount of increase in the number of cn bw progeny, suggesting that the dysfunction switches from a spermatid carrying one homolog to one carrying the other. Negative distortion requires a radical revision of current hypotheses for the mechanism of segregation distortion and a possible modification of the current model is suggested, based on differential recovery of dysfunction in the two homologs during spermiogenesis.

The Effect of Orally Administered Thyrotropin-Releasing Hormone on Growth and Carcass Characteristics of Seven- to Ten-Week-Old Broilers

In contrast to some earlier studies with young broiler chickens, several recent studies have shown growth responses to exogenous growth hormone (GH) administration in broiler chickens of advanced age (Vasilatos-Younken et al., 1988; Scanes et al., 1990). It was therefore of interest to determine whether intermittent feeding of thyrotropin-releasing hormone (TRH), a known GH secretogogue, would elevate plasma GH of 7- to 10-wk-old broilers and alter their growth characteristics.Four replicate pens of 15 males and four pens of 15 females 7 to 10 wk of age were given access to feed containing 3.5 mg/kg of TRH for four 2-h periods each 24 h with 4-h periods of feed removal between. Control groups either were fed the basal ration on the same intermittent schedule or had continuous access to it. Growth hormone concentrations, measured 45 to 75 min after the start of TRH feeding periods, were significantly elevated in males on the 1st day of the experiment and after 7, 14, and 21 days when they were 7, 8, 9, and 10 wk of age, respectively. Concentrations in females were elevated on the 1st day of treatment, but not thereafter. Treatment with TRH had no effect on BW or relative gain of males at any time. It significantly increased relative gain of females during the 1st wk, but not thereafter.There were no treatment effects on 10-wk shank length, Pectoralis major weight, Gastrocnemius weight, or liver weight in either sex, but the percentage fat pad of males fed TRH was lower than that of controls fed intermittently.

Daily Energy Allotment and Reproductive Performance of Broiler Breeder Males

Ross broiler breeder males, housed in floor pens with females and fed from separate feeders, were given 125 g/day of isonitrogenous diets formulated to provide 300, 340, and 380 kcal per male per day between 28 and 60 wk of age. Males given 300 kcal/day maintained their initial BW and were consistently lighter than those fed the two higher energy levels; BW of males given the two higher energy allotments did not differ from each other. Fertility levels, over the whole experiment, averaged 80.1, 91.1, and 83.0% for the low-, intermediate-, and high-energy groups, respectively. Fertility dropped slightly over time in all groups but showed a precipitous fall in the low-energy group between 48 and 60 wk. Hatchability of fertile eggs showed a significant decrease over time but no treatment differences were found. Hatchability of eggs set, like fertility, showed a significant quadratic regression on energy allocation.A significant linear effect of energy level on 60-wk testes weights was found but carcass composition at 60 wk was unrelated to dietary energy allocation. Males fed 300 kcal/day had less severe pododermatitis than males in other groups, but the correlation between BW and pododermatitis score was not significant. Average 6-wk BW of approximately 500 offspring of males fed the low-energy diet, raised comingled with those from other male treatments in three separate growth trials, were consistently and significantly lower than those of offspring of males fed 380 kcal/day.

Increased litter size in Rambouillet sheep: I. Estimation of genetic parameters.

The variance and covariance components needed to estimate heritabilities of and genetic correlations among litter size, ovulation rate, scrotal circumference, and BW in a flock of Rambouillet sheep were estimated using REML via an expectation-maximization type algorithm. The heritability estimates from univariate analyses were .14, .21, .25, .36, and .15 for litter size, ovulation rate, scrotal circumference, 180-d BW of females, and 180-d BW of males, respectively, and average heritability estimates from bivariate analyses were .19, .20, .20, .34, and .10 for litter size, ovulation rate, scrotal circumference, 180-d BW of females, and 180-d BW of males, respectively. The genetic correlation between litter size and ovulation rate was near unity. Body weight in ewes had a moderate genetic correlation with both litter size (.22) and ovulation rate (.20) and a low residual correlation with both litter size (.03) and ovulation rate (.09). The genetic correlation between BW in rams and scrotal circumference was 0, whereas the residual correlation was .71. The genetic correlations of scrotal circumference with litter size and ovulation rate were -.25 and +.20, respectively.

Effect of Diet and Population Density on Male Turkeys Under Various Environmental Conditions.: 1. Turkey Growth and Health Performance

The performance of 1,312 male market turkeys (Large White, Nicholas strain) from 0 to 20 wk of age fed diets varying in feed form and energy level was measured under two stocking densities (.21 or .46 m2 per bird) and four lighting and temperature programs. The four diets were 1) corn and soybean meal with 1% supplemental fat, mash (CSM); 2) as 1, pelleted (CSP); 3) as Diet 1 but with 1, 2, 4, 6, and 8% supplemental fat during 0 to 4, 4 to 8, 8 to 12, 12 to 16, and 16 to 20 wk of age, respectively (CSF); and 4) as Diet 1 but with barley included at 0, 20, 35, 50, and 65% during the respective 4-wk age periods (CSB). The four light and temperature programs were 1) Environment A with intermittent light [4[2 h light (L):4 h dark (D)]] in combination with cycling temperature at 7 and 21 C during light and dark photoperiod, respectively; Environment B with intermittent light, 21 C; Environment C with continuous light (18L:6D) and cycling temperature of 7 to 21 C; and Environment D with intermittent light, 7 C. Lighting and temperature programs started at 1 and 4 wk of age, respectively.Body weights at 20 wk of age decreased (P<.05) with increasing temperature (13.86 versus 12.26 kg for Environments D and B, respectively) with cycling temperature intermediate (13.51 kg for Environment A). Intermittent light (P<.05) improved BW and feed conversion by 3.4 and 2.0%, respectively, compared with continuous light. Rearing males at .21 m2 per bird versus .46 m2 per bird decreased weight (P<.05) by 5.5%. Twenty-week BW of males fed the CSP (13.52 kg) and CSF (13.58 kg) diets were greater (P<.05) than those fed CSM (12.90 kg) and CSB (12.69 kg) diets. Significant (P<.05) interactions between diet, environment, and density were not detected for most performance characteristics.Environmental measurements indicated higher dust and ammonia levels in the warm environment (B). Isolates of aspergillus and incidence of airsacculitis at time of processing were greatest in Environment B.

Divergent Selection for Body Weight and Yolk Precursor in Coturnix coturnix japonica.: 8. A Summary of Correlated Responses

Correlated response data accompanying 19 generations of selection for increased (HW) or decreased (LW) 4-wk BW and increased (HP) or decreased (LP) total plasma P were summarized. Similarly, 11 generations of selection of sublines derived from the original Lines HW and LP were also analyzed. Sublines were maintained through selection of males for increased 4-wk BW and females for the respective high or low plasma P.The randombred control (RBC1) was stable for BW early in egg production, BW change from early to late in production, wet and dry liver weights, 120-day egg production, and ova weight. A linear decrease in BW was found for the RBC1 line late in egg production, egg and respective component weights, and ova number. Body weight early and late in the production period for original Lines HW and LW was different from the RBC1 line. Wet liver weight increased for the HW line while dry liver weights declined in the original Lines LW, HP, and LP. Egg weights were greater in Line HW and lower in Lines LW, HP, and LP than in the RBC1 line. Yolk weight increased in Line HW and decreased in Lines LW and LP. Albumen weight was reduced in Line LP while shell weight was increased in Line HW and decreased in Line HP. Egg production, from onset to 120 days, decreased in Lines HW and LW when compared to the RBC1 line. Line LP had more follicles in rapid development than Line RBC1. The sublines responded similarly to their line of origin differing only in the magnitude of response. This was a reflection of the mating scheme, which placed selection pressure on BW of males and plasma P in females.

Carcass Traits of Turkeys from Lines Selected for Increased Growth Rate or Increased Shank Width

Carcass composition of turkeys from a long-term growth-selected line (F), a subline (FL) of F selected only for increased shank width, and a randombred control population (RBC2) that served as the base population for F, were compared. Birds of both sexes were killed at 16 wk of age in the fifth and sixth generations in Line FL. A commercial sire line (C) was also included in the sixth generation.Body weight increased at comparable rates in F and FL males through the 5th generation of selection in Line FL, but the BW of FL males was significantly smaller than that observed in F males in the 6th generation. Body weights of FL females were significantly lower than BW of F females in both the 5th and 6th generations, resulting in a significant line × sex interaction. A similar interaction was also observed in both generations in the actual weight of most leg bones, leg muscles, and breast muscles. When expressed as a percentage of live BW, most of the latter line × sex interactions were not significant.Genetic increases in shank width of the FL line were associated with increases in the relative weight of all leg bones measured and drumstick muscles. This may have contributed to the improved walking ability consistently observed in FL males relative to that of F males. In general, genetic increases in BW in Line F were associated with a decreased amount of relative support (leg muscles and leg bones) in comparison with that observed in Line RBC2. These results support the hypothesis that a portion of the leg problems observed in large-bodied turkeys are attributable to an inherent weakness of body support structures resulting from the slower growth of these structures relative to that of total BW.

SD-72 has a temperature-sensitive period during spermiogenesis

Segregation distorter (SD) chromosomes in Drosophila melanogaster are naturally occurring second chromosomes which produce greatly altered transmission frequencies when present in heterozygous males (Hartl and Hiraizumi 1976). The proximate cause of segregation distortion is abortion of spermatids carrying the non-SD homologue (Tokuyasu et al. 1977). SD-72, a chromosome previously shown (Mange 1968) to be unaffected by high temperature treatment of spermatocytes, a stage when several SD genotypes are temperature sensitive, has a temperature-sensitive period during spermiogenesis. SD-72/cn bw males exposed to a 24-h pulse of 29 °C, then brooded for 24 h, experience a decrease in segregation distortion of approximately two-thirds. The timing of the reduction in distortion indicates that the temperature-sensitive period is postmeiotic.

Behavior and single gene substitution inDrosophila melanogaster. I. Mating and courtship differences withw, cn, andbw Loci

The effect of single allele substitutions into an isogenic background in Oregon-R inbred lines of Drosophila melanogaster on courtship and mating patterns has been studied. A comparison has been made between the white locus w, wco, we, the wild type w+, cn, bw, and cn bw to test the effect of eye pigmentation in influencing courtship and mating patterns. It was found that w, we, wco, cn, and bw females were more successful in mating than were wild-type and cn bw females, cn bw females being less successful than wild-type females. Also, w and cn bw males were equally successful in mating but less successful than wild-type males during the 20-min test period. The mutant males performed as well as the wild-type after courtship was initiated. The behavioral parameters measured were (1) courtship latency, the time from exposure of male to female until orientation; (2) mating speed, the time from beginning of orientation of male to female until successful copulation, and (3) copulation time.

Progeny: sperm ratios and segregation-distorter in Drosophila melanogaster.

Progeny: sperm ratios (P/S) were determined from crosses ofSD/cn bw males ofDrosophila melanogaster with females of eight different genotypes. Thek value was about 1.0. P/S ratios of 0.88, 0.81, and 0.76, respectively, were observed from crosses with females of three genotypes, and ratios in the 0.3–0.4 range from five. These results support the suggestion ofZimmering & Fowler (1968) that P/S ratios may vary widely and depend at least in part on the genotype of the female. Morcover, since P/S ratios of 0.9 may be observed whenk is about 1.0, it follows that the vast majority of sperm stored in these females areSD.

MEIOTIC DRIVE IN NATURAL POPULATIONS OFDROSOPHILA MELANOGASTER. VIII. A HERITABLE AGING EFFECT ON THE PHENOMENON OF SEGREGATION-DISTORTION

Second chromosomes have been found in natural populations of Drosophiln nzelanognster that contain an abnormal centromere region which conditions a highly aberrant segregation ratio in heterozygous males (Sandler, Hiraizumi, and Sandler, 1959). In particular, when a chromosome carrying this abnornlal region (symbolized SD for Segregation-distorter) is made heterozygous with a normal second chronlosome (routinely a standard tester chronlosome inarlted by the recessives cyz and bw) in males, and bacltcrossed to homozygous C17 bw females, 90 per cent or more of the F1 receive the SD-bearing second chromosome. These abnormal segregation ratios are not accompanied by egg mortality. It has now ,been found that as heterozygous SD males are aged, the segregation ratios become less abnormal. When, moreover, young sons of awed ? fathers are examined, it is found that they too exhibit less extreme segregation ratios. Indeed, changes in the segregation ratio induced by aging may persist in selected ,males for at least five generations and possibly indefinitely. T h e evidence demonstrating a heritable aging effect and a consideration of certain other questions relevant to the aging phenonlenon are presented below.

Experimental breeding of offsprings of lethal ovaries of a mutant letal-translucida from Drosophila melanogaster

Ovaries of larvae homozygous for the genelethaltranslucida (ltr) were transplanted in female larvaefes cn bw/fes cn bw. In the cases that an attachment of the implanted ovaries to the oviducts of the host took place, the sterile females after mating withcn bw/cn bw males gave a normal offspring, which genetically could be recognized as originating from thelethal-translucida ovaries.