• Asian-Australasian Journal of Animal Sciences
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• v.10 no.4
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• pp.416-421
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• 1997

The effect of imported young bulls on the genetic progress was examined in the Holstein dairy cattle population in Japan. The effect of the difference of mean genetic merit between imported and domestic young bulls ("genetic difference") was recognized on the genetic progress of the domestic animals in the early stage of selection. On the other hand, the genetic progress of domestic animals were remarkably influenced by the genetic trend of imported young bulls ("genetic trend") in the later stage. Import of young bulls originated from high genetic level of young bulls originated from high genetic level population improved the genetic progress of domestic population. But, the increase of the immigration ratio of imported young bulls ("immigration ratio") did not influence linearly on the progress of the genetic merit of domestic animals. Even if "immigration ratio" was 100%, the genetic merit of domestic animals could not overcome the one of imported young bulls. In the later stage of selection, the genetic merit of domestic animals ran parallel to those of imported young bulls.

• Journal of Animal Science and Technology
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• v.51 no.2
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• pp.105-110
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• 2009

The Objective of this study was to compare performances of proven and young holstein bulls bred in Korea. Proven bulls are categorized into the imported and the korean ones. Data from 148,329 heads of daughters of 1,128 bulls from 1990 to 2004 were used in this study. Proven bulls showed higher milk yield than young bulls in same year. Young bulls, however, always yielded more milk than korean bulls when proven bulls were categorized into the imported and the korean ones. Hence, it was proven that dairy bull selection program had properly been functioned in Korea. Selected bulls, which were korean proven bulls and young bulls, yielded higher milk fat than imported bulls as the selection was weighted on the yield of the milk fat. This comparison was based on the performances of daughters without the consideration of the semen price. Semen price of the imported proven bulls were higher than the korean proven bulls and the semen of young bulls was free. Hence, the performances of korean bulls with the consideration of the preferential effect would be much higher than others, and further studies are necessary.

• Asian-Australasian Journal of Animal Sciences
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• v.27 no.11
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• pp.1554-1561
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• 2014

Present study analyzed the changes in peripheral blood testosterone concentrations and testicular cytogram in relation to age and semen quality in crossbred males. Three different age groups of crossbred males viz. bull calves (6 months, n = 5), young bulls (15 months, n = 5) and adult bulls (4 to 6 years, n = 8) were utilized for the study. Testicular fine needle aspiration cytology technique was used to quantify testicular cytology and their indices. Peripheral blood testosterone concentrations were measured using enzyme-linked immunosorbent assay method. Semen samples collected from adult bulls were microscopically evaluated for quality parameters. Mean peripheral blood testosterone concentrations in bull calves, young bulls and adult bulls were $2.28{\pm}0.09ng/mL$, $1.42{\pm}0.22ng/mL$ and $5.66{\pm}1.08ng/mL$ respectively, and that in adult bulls were significantly different (p<0.01) from young bulls and bull calves. There was no significant difference between the proportion of different testicular cells in bull calves and young bulls. Between young and adult bulls, significant differences (p<0.01) were observed in the proportion of spermatocytes, spermatozoa, and sperm: Sertoli cell ratio. The proportions of Sertoli cells showed a significant difference (p<0.01) between the three age groups. The number of primary spermatocytes had a positive correlation with peripheral blood testosterone concentrations in bull calves (r = 0.719, p<0.01). Number of Sertoli cells per 100 germ cells was negatively correlated with blood testosterone concentration in young bulls (r = -0.713, p<0.01). Among different semen parameters in adult bulls, ejaculate volume (r = 0.790, p<0.05) had positive relationship, and sperm motility had significant negative correlation (r = -0.711, p<0.05) with testosterone concentrations. The number of Sertoli cells and Sertoli cell index had a positive correlation with various semen quality parameters (p<0.001). Results of the present study conclude that number of Sertoli cells and Sertoli cell index are good indicators of semen quality, but peripheral blood testosterone concentrations may not have a direct relationship with various seminal attributes in crossbred bulls.

• Journal of Animal Science and Technology
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• v.52 no.4
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• pp.253-258
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• 2010

This study was conducted to compare the phenotypic performance and genetic merits in terms of weight at 12 months, carcass weight, eye muscle area, backfat thickness, marbling score and selection index of Hanwoo young bulls and proven bulls from the year 2004 to 2006. The data of 208 bulls used in this study were taken from the Nnational Hanwoo genetic evaluation coordinated by National Institute of Animal Science. Hanwoo young bulls were superior in the phenotypic performance of weight at 12 months, carcass weight, and eye muscle area showing significant differences from Hanwoo proven bulls in most comparisons. The backfat thickness of Hanwoo young bulls was significantly thicker higher than Hanwoo proven bulls in all comparisons (p < 0.05). Also, Hanwoo young bulls were not significantly different from Hanwoo proven bulls in the genetic merits of weight at 12 months, carcass weight, eye muscle area, backfat thickness, marbling score, and total genetic merits. Performance of Hanwoo young bulls were not significantly different from 1st class of Hanwoo proven bulls in all the traits studied except in eye muscle area.

• Asian-Australasian Journal of Animal Sciences
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• v.11 no.4
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• pp.410-415
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• 1998

The effects of the proprotion of cows inseminated by young A. I. bulls on genetic improvement in the Japanese Holstein population were examined using a simulation technique. The proportion of recorded cows inseminated by young A. I. bulls was assumed to be from 10% to 100% of the total number of recorded cows. The expected total genetic improvement was estimated for all cows and recorded and non recorded cows. The effects of the above were remarkable in the schemes that proven sires were used to produce recorded and non recorded cows for a limited time. Also the increase in the rates for -the expected total genetic improvement was larger when the proportion of recorded cows that were inseminated by young A. I. bulls was about 10% to 40%. When the expected total genetic improvement was estimated for the entire population, we found that the highest values were in a range of about 40 to 60% recorded cows that were inseminated by young A. I. bulls. On the other hand, the expected total genetic improvement that was only estimated in recorded cows dramatically decreased for more than 40% of the recorded cows. The results of this study showed that the optimal proportion of recorded cows inseminated with young A. I. bulls should be about 30% in the Japanese Holstein population.

• Asian-Australasian Journal of Animal Sciences
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• v.20 no.1
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• pp.12-18
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• 2007

The objective of the study was to compare ranking of Sahiwal bulls selected on the basis of highest lactation milk yield of their dams with their estimated breeding values (EBVs) using an animal model. Data on 23,761 lactation milk yield records of 5,936 cows from five main Livestock Experiment Stations in Punjab province of Pakistan (1964-2004) were used for the study. At present the young A.I bulls are required to be from A-category bull-dams. Dams were categorized as A, B, C and D if they had highest lactation milk yield of ${\geq}$2,700, 2,250-2,699, 1,800-2,249 and <1,800 litres, respectively. The EBVs for lactation milk yield were estimated for all the animals using an individual animal model having fixed effect of herd-year and season of calving and random effect of animal. Fixed effect of parity and random effect of permanent environment were incorporated when multiple lactation were used. There were 396 young bulls used for semen collection and A.I during 1973-2004. However, progeny with lactation yields recorded, were available only for 91 bulls and dams could be traced for only 63 bulls. Overall lactation milk yield averaged 1,440.8 kg. Milk yield was 10% heritable with repeatability of 39%. Ranking bulls on highest lactation milk yield of their dams, the in-vogue criteria of selecting bulls, had a rank correlation of 0.167 (p<0.190) with ranking based on EBVs from animal model analysis. Bulls' EBVs for all lactations had rank correlation of 0.716 (p<0.001) with EBVs based on first lactation milk yield and 0.766 (p<0.001) with average EBVs of dam and sire (pedigree index). Ranking of bulls on highest lactation yield of their dams has no association with their ranking based on animal model evaluation. Young Sahiwal bulls should be selected on the basis of pedigree index instead of highest lactation yield of dams. This can help improve the genetic potential of the breed accruing to conservation and development efforts.

• Animal Bioscience
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• v.34 no.5
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• pp.914-921
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• 2021

Objective: The objective of this study was to compare growth performance, carcass traits and meat quality in young bulls, steers and heifers produced by crossing Limousin bulls with Holstein-Friesian cows, fattened semi-intensively and slaughtered at 18 months of age. Methods: Thirty-one young calves were reared in a conventional production system, and were fed milk replacer, hay and concentrate. At 6 months of age, the animals were divided into groups based on gender, and were fed a total mixed ration composed of grass silage, concentrates I and II in a semi-intensive production system. At the end of the fattening period (18 months), the animals were slaughtered, carcass quality was evaluated, and samples of musculus longissimus thoracis were collected to determine the proximate composition and quality of meat. Results: Bulls were characterized by the highest percentage share of the most valuable cuts in the carcass, and three-rib sections from bull carcasses had the highest lean meat content with low intramuscular fat content (0.93%). No significant differences in carcass conformation, dressing percentage or the percentage share of round in the right half-carcass were found between bulls vs. steers and heifers. Heifers and steers had higher carcass fat content than bulls, which had a positive influence on the sensory properties of beef. In comparison with the meat of bulls, the meat of steers and heifers was characterized by more desirable physical properties and sensory attributes (water-holding capacity, shear force, color lightness, aroma, juiciness, tenderness, flavor). Conclusion: Under the semi-intensive production system, heifers and steers had higher carcass fat content than bulls, which had a positive effect on the sensory properties of beef. Bulls are better suited for intensive systems, which contribute to improving the quality of their meat. The results of this study may encourage producers to breed steers and heifers for beef.

• Asian-Australasian Journal of Animal Sciences
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• v.32 no.8
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• pp.1211-1218
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• 2019

Objective: The objective of this study was to determine the effects of age and gender (bull vs steer) on feeding behavior parameters in young beef cattle fed grass silage. Methods: The study was conducted on 180 young beef cattle at 7 to 18 mo of age. The experimental materials comprised 90 bulls produced by commercial crossing of Polish Holstein-Friesian cows with Charolais, Limousin and Hereford bulls (30 animals of each breed) and 90 steers of the same genotypes. The animals had ad libitum access to grass silage; the concentrate was fed separately, in feed stations. They received 28 g dry matter of concentrate per kg of metabolic body weight per day. Bunk visit data and silage intake for all experimental animals were recorded individually using the Roughage Intake Control system (5 feed bunks per 15 animals). Results: Age and gender (bull vs steer) exerted significant effects on the feeding behavior of young beef cattle. The frequency of bunk visits and meal frequency decreased, whereas the feeding rate of silage, and the average duration and size of a single meal increased with age (p<0.01). Bunk attendance and meal frequency were higher (p<0.01) in steers than in bulls (49.1 vs 37.4 visits/d, and 8.63 vs 7.99 meals/d, respectively). Daily feeding time was longer in steers than in bulls (102.3 vs 100.3 min/d, respectively), but the feeding rate of silage was lower in steers, and their meals were smaller in size and shorter in duration (p<0.01). Daily silage dry matter intake was higher (p<0.01) in bulls than in steers (4.62 vs 4.47 kg/d, respectively). Conclusion: The results of this study indicate that age and gender (bull vs steer) exerted significant effects on the feeding behavior of young beef cattle.

• Asian-Australasian Journal of Animal Sciences
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• v.11 no.2
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• pp.117-120
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• 1998

Relationships of breeding values of sires for first lactation milk yield with pedigree information or indices were examined to identify the optimal criteria of selecting young dairy bulls for future use in artificial insemination (AI). Records of performance data on 1087 crossbred daughters (Holstein - Friesian, Jersey and Brown Swiss with Hariana) of 147 sires, generated at Livestock Production Research (Cattle and Buffaloes) Farm, IVRI, Izatnagar, U.P., during 1972 - 1995 were used to obtain the estimates of sire's breeding values (EBV) using the Best Linear Unbiased Prediction Procedures. The correlations between young bull's EBV and the dam's first lactation milk yield was non-significantly different from zero. However, the young bull's EBV was negatively and significantly related (r = - 0.275 ; P < 0.05) to the dam's best lactation milk yield, suggesting that the selection of young dairy bulls from high yielding elite dams is not a suitable criteria for genetic improvement. The correlations of sire's and paternal grandsire's EBV's with young bull's EBV were high and positive (0.532, 0.844; P < 0.01). The maternal grandsire's EBV was positively but non-significantly related to grandson's EBV. The pedigree index incorporating dam's milk records and sire's EBV's showed a negative and non-significant correlation with young bull's EBV. However, the correlation of a pedigree index $(I_3)$ combining information on sire's and paternal grand-sire's EBV's with young bull's EBV's was considerably high and positive (0.797; P < 0.01). The regression coefficients of young bull's EBV on pedigree index $I_3$, was higher than those on other pedigree information. These results revealed that there was no advantage in basing selection on dam's performance or maternal grand-sire's EBV and that sire's and paternal grandsire's EBV's were reliable pedigree information for selection of young dairy bulls for future use in AI.

• Asian-Australasian Journal of Animal Sciences
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• v.8 no.4
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• pp.337-342
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• 1995

Two feeding trials were conducted to determine the effect of molasses feeding on the growth performances of bulls. In the first experiment, the straw of a control diet of straw and urea was replaced by molasses of 150 g ($M_{150}$) or $300g{\cdot}kg^{-1}$ ($M_{300}$). The three diets were fed ad libitum to three groups of bulls having five in each and the dietary responses were statistically analyzed in a simple design. The bulls were given fishmeal ($30g{\cdot}hd^{-1}{\cdot}d^{-1}$), wheat bran (0.5% of Liveweight, LW) and allowed grazing for $5hrs{\cdot}d^{-1}$. Molasses supplementation significantly (p < 0.001) increased the dry matter intake (DMI) of the bulls of $M_{150}$ (35.8g) and of $M_{300}$ (42.9g) than the control ($30.4g{\cdot}kg^{-0.75}$). The daily LW gain of the bulls of the $M_{150}$ (982g) was significantly (p < 0.05) higher than the bulls of the control or of the $M_{300}$ diet. In the second experiment, a control group of four bulls was fed a straw diet. Treatment two groups, having four bulls in each, were fed a mixed diet of Leucaena leucocephala and Setaria splendida(1:1, DM basis) with (LSM) and without (LS) molasses at $100g{\cdot}kg^{-1}$. The dietary responses were statistically analyzed in a simple design. The bulls of the LSM diet had significantly (p < 0.05) higher DMI, DM digestibility and LW gain ($128g{\cdot}kg^{-0.75}$, $663g{\cdot}kg^{-1}$ and $419g{\cdot}d^{-1}$, respectively) than the bulls of the LS diet ($98.3g{\cdot}kg^{-0.75}$, $583g{\cdot}kg^{-1}$ and $292g{\cdot}d^{-1}$, respectively). But the differences between the LSM and the control were nonsignificant. It may be concluded that molasses may be utilized as supplement to straw at $150g{\cdot}kg^{-1}$ or forages at $100g{\cdot}kg^{-1}$ diet for the profitable beef production from young growing bulls.