Genetic parameters for body weights,egg traits and antibody response against Newcastle Disease Virus (NDV) vaccine among two Tanzania chicken ecotypes

Genetic parameters were estimated for production traits and primary antibody response (Ab) against Newcastle diseases virus (NDV) vaccine among two Tanzania chicken ecotypes viz. Kuchi and Tanzania Medium (Medium). Production traits studied were body weights at 8 (Bwt8), 12(Bwt12), 16(Bwt16), and 20 (Bwt20) weeks of age, age at first egg (AFE), egg number in the first 90 days after sexual maturity (EN-90), egg weight (EW), egg shell thickness (STH), and egg shape index (ESI). Heritability estimates for Bwt8, Bwt12, Bwt16, Bwt20, AFE, EN-90, EW, STH, ESI and Ab for Kuchi chicken were 0.38 ± 0.10, 0.41 ± 0.07, 0.44 ± 0.08, 0.45 ± 0.09, 0.42 ± 0.10, 0.31 ± 0.05, 0.43 ± 0.08, 0.53 ± 0.11, 0.48 ± 0.13 and 0.27 ± 0.06, respectively. Corresponding estimates for Medium ecotype were 0.39 ± 0.09, 0.43 ± 0.10, 0.42 ± 0.08, 0.43 ± 0.07, 0.52 ± 0.11, 0.32 ± 0.06, 0.50 ± 0.07, 0.61 ± 0.13, 0.52 ± 0.10 and 0.29 ± 0.05, respectively. Genetic (r _g) and phenotypic (r_p) correlations in both ecotypes were highest among body weights (i.e. r_g = 0.60 to 0.93 and r_p = 0.54 to 0.78), and were lowest (around 0.10 and below, ranging from positive to negative) among primary antibody response against NDV vaccine and production traits, and among eggshell thickness, egg shape index and other production traits. The magnitudes of heritability estimates obtained in this study indicate good prospects of improving these traits in both ecotypes through selection.     

Estimates of (co)variance components and genetic parameters for growth traits of Avikalin sheep

(Co)variance components and genetic parameters for various growth traits of Avikalin sheep maintained at Central Sheep and Wool Research Institute, Avikanagar, Rajasthan, India, were estimated by Restricted Maximum Likelihood, fitting six animal models with various combinations of direct and maternal effects. Records of 3,840 animals descended from 257 sires and 1,194 dams were taken for this study over a period of 32 years (1977–2008). Direct heritability estimates (from best model as per likelihood ratio test) for weight at birth, weaning, 6 and 12 months of age, and average daily gain from birth to weaning, weaning to 6 months, and 6 to 12 months were 0.28 ± 0.03, 0.20 ± 0.03, 0.28 ± 0.07, 0.15 ± 0.04, 0.21 ± 0.03, 0.16 and 0.03 ± 0.03, respectively. Maternal heritability for traits declined as animal grows older and it was not at all evident at adult age and for post-weaning daily gain. Maternal permanent environmental effect (c ²) declined significantly with advancement of age of animal. A small effect of c ² on post-weaning weights was probably a carryover effect of pre-weaning maternal influence. A significant large negative genetic correlation was observed between direct and maternal genetic effects for all the traits, indicating antagonistic pleiotropy, which needs special care while formulating breeding plans. A fair rate of genetic progress seems possible in the flock by selection for all traits, but direct and maternal genetic correlation needs to be taken in to consideration.     

Genetic and phenotypic parameter estimates for reproduction traits in indigenous Arsi-Bale goats

The study was conducted to evaluate reproductive performances and estimate genetic parameters for reproduction traits in Arsi-Bale goats. A total of 792 kidding records collected from 2001 to 2007 were used. Parity of dam, year, season and type of kidding were investigated as fixed effects by PROC GLM of SAS. Derivative-Free Restricted Maximum Likelihood (DFREML) method was used to estimate genetic parameters by fitting four animal models. Parity of dam and year of kidding influenced (P < 0.05) all the traits. The overall means for age at first kidding (AFK), kidding interval (KI), litter size at birth (LSB), litter size at weaning (LSW), litter weight at birth (LWB), litter weight at weaning (LWW), abortion and dystocia were 574.9 ± 8.3 days, 280.0 ± 13.7 days, 1.6 ± 0.03, 1.37 ± 0.03, 3.7 ± 0.08 kg, 9.11 ± 0.38 kg, 3.8% and 0.13%, respectively. The estimates of direct additive heritability for the traits, except for abortion and dystocia, under the best model (direct animal for AFK and repeatability model for other traits) were 0.245 ± 0.19, 0.060 ± 0.08, 0.074 ± 0.05, 0.006 ± 0.05, 0.125 ± 0.05, 0.053 ± 0.07, respectively, while the corresponding permanent environmental effects were 0.00 ± 0.00, 0.07 ± 0.07, 0.08 ± 0.05, 0.172 ± 0.06, 0.03 ± 0.04 and 0.07 ± 0.05, respectively. Repeatability estimates for KI, LSB, LSW, LWB and LWW were 0.13, 0.15, 0.18, 0.16 and 0.12, respectively. Genetic correlations between reproductive traits vary from medium to high. Arsi-Bale goats have good reproductive performance with low incidence of reproductive disorder. Except for AFK, other traits have low estimates of heritabilities with high genetic correlation among the traits. Repeated measures of the traits are needed before deciding to keep or cull the animal.     

Estimation of genetic parameters for body weight and egg production traits in Mazandaran native chicken

Native chicken breeding station of Mazandaran was established in 1988 with two main objectives: genetic improvement through selection programs and dissemination of indigenous Mazandarani birds. (Co)variance components and genetic parameters for economically important traits were estimated using (bi) univariate animal models with ASREML procedure in Mazandarani native chicken. The data were from 18 generations of selection (1988?C2009). Heritability estimates for body weight at different ages [at hatch (bw1), 8 (bw8), 12 (bw12) weeks of ages and sex maturation (wsm)] ranged from 0.24?±?0.00 to 0.47?±?0.01. Heritability for reproductive traits including age at sex maturation (asm); egg number (en); weight of first egg (ew1); average egg weight at 28 (ew28), 30 (ew30), and 32 (ew32) weeks of age; their averages (av); average egg weight for the first 12?weeks of production (ew12); egg mass (em); and egg intensity (eint) varied from 0.16?±?0.01 to 0.43?±?0.01. Generally, the magnitudes of heritability for the investigated traits were moderate. However, egg production traits showed smaller heritability compared with growth traits. Genetic correlations among egg weight at different ages were mostly higher than 0.8. On the one hand, body weight at different ages showed positive and relatively moderate genetic correlations with egg weight traits (ew1, ew28, ew30, ew32, ew12, and av) and varied from 0.30?±?0.03 to 0.59?±?0.02. On the other hand, low negative genetic correlations were obtained between body weight traits (bw1, bw8, bw12, and wsm) and egg number (en). Also, there is low negative genetic correlation (?24?±?0.04 to ?29?±?0.05) between egg number and egg weight. Therefore, during simultaneous selection process for both growth and egg production traits, probable reduction in egg production due to low reduction in egg number may be compensated by increases in egg weight.     

Evaluation of two Indian native chicken breeds for reproduction traits and heritability of juvenile growth traits

The present study was conducted to evaluate two Indian native chicken breeds, namely, Aseel and Kadaknath for fertility, hatchability, genetic parameters of juvenile growth traits, and semen quality traits at the onset of sexual maturity. The fertility was similar in Aseel (86.96%) and Kadaknath (85.15%); however, a relatively higher hatchability was observed in Kadaknath (77.94%) than Aseel (70.74%). Heritability estimates of body weights at 4 weeks of age were almost similar in Aseel (0.37) and Kadaknath (0.39), while the estimate of body weight at 6 weeks of age was higher in Aseel (0.42) than Kadaknath (0.31). The heritability estimate of shank length at 6 weeks of age was lower in Aseel (0.16) compared to Kadaknath (0.35). The age at first egg in the flock was comparable in Aseel (148 days) and Kadaknath (150 days). Aseel breed with significantly (P ≤ 0.001) higher body weight, absolute and relative testes weights had significantly higher semen volume (P ≤ 0.05) and sperm motility (P ≤ 0.01) but had lower seminal plasma cholesterol level (P ≤ 0.05) as compared to Kadaknath. It can be concluded that there is a scope for genetic improvement of these two native breeds for juvenile growth traits since heritability estimates of these traits were relatively high.     

Birth weight,reproduction traits and effects of inbreeding in Nicaraguan Reyna Creole cattle

Reyna Creole cattle in Nicaragua comprise about 650 purebred animals, and the breed has been shown to have a high level of inbreeding. To characterize the breed, as basis for a conservation program, information from two herds on birth weight (BW, n = 1097), age at first calving (AFC, n = 449) and calving interval (CI, n = 1,347) was analysed. Overall averages were 27.8 kg for BW, 37.4 months for AFC and 424 days for CI. Large differences between the herds were observed for all traits. Thus, there would be opportunities for management interventions to improve reproduction results. The heritability for BW was 0.34. For CI, the heritability of 0.20 and the additive genetic standard deviation of 36 days were comparatively high values. No genetic variation was found in AFC. Estimated inbreeding effects were associated with large standard errors due to the small size of the data and incompleteness of pedigrees. Nevertheless, significant effects were shown of dam inbreeding level on all traits. For each percentage of increased inbreeding, BW decreased by 0.06 kg, AFC increased by 3.5 days and CI increased by 1.4 days. The effects of the inbreeding level of the individual itself were not significant. The relatively good reproduction traits of Reyna Creole cattle shown in this study, despite high inbreeding levels, will be supplemented with a characterization of milk production traits.     

Genetic analysis for growth traits of prolific Garole × Malpura (GM) sheep

The FecB gene of Garole sheep was introgressed into non-prolific Malpura sheep to evolve a new prolific sheep strain Garole × Malpura (GM), suitable for semi-arid conditions. The present study was conducted to evaluate the impact of breeding program on production profile of GM sheep and to estimate the genetic parameters for growth traits of GM sheep. Overall prolificacy increased significantly in the new strain as compared to the native Malpura sheep. In the GM flock of F2 and F2 onwards generation 35.31% single, 55.83% twins, 8.16% triplet and 0.70% quadruplets were obtained during lambing. Over the years, prolificacy in the flock has increased significantly. Over all least squares means for birth weight, 3, 6, 9, 12 month weight, pre-weaning gain (ADG1) and post-weaning gain (ADG2) were 1.82 ± 0.03, 9.44 ± 0.18, 14.00 ± 0.24, 16.56 ± 0.33, and 19.32 ± 0.35 kg, and 84.08 ± 1.84 and 35.19 ± 0.99 g, respectively. Majority of the fixed effects had significant influence on the performance traits. The heritability estimates for birth, 3, 6, 9, 12 month weight, ADG1 and ADG2 were 0.30 ± 0.11, 0.22 ± 0.09, 0.23 ± 0.10, 0.27 ± 0.10, 0.30 ± 0.11, 0.17 ± 0.08, and 0.17 ± 0.10, respectively. Modest rate of genetic progress seems possible for these traits under selection. The genetic and phenotypic correlations among different body weights were moderate to high and positive. The genetic correlation of pre and post-weaning daily gains with body weight traits were also high and positive.     

Relationship of age to body weight,scrotal circumference,testicular ultrasonograms,and semen quality in Sahiwal bulls

The objective of the present study was to determine the relationship of age to body weight (BW), scrotal circumference (SC), number of pixels of testicular ultrasonograms (NP), and semen quality in Sahiwal bulls. The study was based on 128 Sahiwal bulls of different age groups (from 0 to >100 months of age). Bulls were evaluated for SC, BW, and NP. Semen was evaluated once a week for five consecutive weeks from regularly collected donor bulls (n = 86) ranging in age from 25–30 to >100 months. Ejaculate volume, sperm motility, sperm concentration, sperm morphology, percent live sperms, sperm plasma membrane integrity, and normal acrosome were compared among different age groups. Mean SC and BW increased (P < 0.05) in a curvilinear manner from birth to >100 months of age. Mean NP of testicular ultrasonograms increased (P < 0.05) from 0 to 24 months and then plateaued until >100 months of age. Body weight, SC, and NP were positively correlated with age from birth until >100 months (r = 0.91, 0.87, and 0.40, respectively). Ejaculate volume (5.7 ± 0.2 vs. 4.6 ± 0.09 ml) and sperm concentration (1,281.6 ± 17.7 vs. 1,115.8 ± 55.9 × 10⁶/ml) increased (P < 0.05) in mature bulls compared to younger ones. However, motility (68.6 ± 0.3%), plasma membrane integrity (50.8 ± 1.0%), and normal acrosome (74.8 ± 0.5%) remained insignificant due to age. In six of eight age groups studied, morphological abnormalities were well within the range (18.1 ± 0.3%). In conclusion, the BW, SC, and NP of testicular ultrasonograms, ejaculate volume, and concentration increased with age. Moreover, semen quality is fairly independent of age except volume and concentration in Sahiwal bulls.     

Direct and maternal (co)variance components,genetic parameters and annual trends for growth traits of Dorper sheep in semi-arid Kenya

Genetic and phenotypic parameters were estimated for lamb growth traits for the Dorper sheep in semi-arid Kenya using an animal model. Data on lamb growth performance were extracted from available performance records at the Sheep and Goats Station in Naivasha, Kenya. Growth traits considered were body weights at birth (BW0, kg), at 1 month (BW1, kg), at 2 months (BW2, kg), at weaning (WW, kg), at 6 months (BW6, kg), at 9 months (BW9, kg) and at yearling (YW, kg), average daily gain from birth to 6 months (ADG_0–6, gm) and from 6 months to 1 year (ADG_6–12, gm). Direct heritability estimates were, correspondingly, 0.18, 0.36, 0.32, 0.28, 0.21, 0.14, 0.29, 0.12 and 0.30 for BW0, BW1, BW2, WW, BW6, BW9, YW, ADG_0–6 and ADG_6–12. The corresponding maternal genetic heritability estimates for body weights up to 9 months were 0.16, 0.10, 0.10, 0.19, 0.21 and 0.18. Direct-maternal genetic correlations were negative and high ranging between −0.47 to −0.94. Negative genetic correlations were observed for ADG_0–6–ADG_6–12, BW2–ADG_6–12, WW–ADG_6–12 and BW6–ADG_6–12. Phenotypic correlations ranged from 0.15 to 0.96. Maternal effects are important in the growth performance of the Dorper sheep though a negative correlation exists between direct and maternal genetic effects. The current study has provided important information on the extent of additive genetic variation in the existing flocks that could now be used in determining the merit of breeding rams and ewes for sale to the commercial flocks. The estimates provided would form the basis of designing breeding schemes for the Dorper sheep in Kenya. Implications of the study to future Dorper sheep breeding programmes are also discussed.     

Direct and maternal (co)variance components and genetic parameters for growth and reproductive traits in the Boran cattle in Kenya

Direct and maternal (co)variance components and genetic parameters were estimated for growth and reproductive traits in the Kenya Boran cattle fitting univariate animal models. Data consisted of records on 4502 animals from 81 sires and 1010 dams collected between 1989 and 2004. The average number of progeny per sire was 56. Direct heritability estimates for growth traits were 0.34, 0.12, 0.19, 0.08 and 0.14 for birth weight (BW), weaning weight (WW), 12-month weight (12W), 18-month weight (18W) and 24-month weight (24W), respectively. Maternal heritability increased from 0.14 at weaning to 0.34 at 12 months of age but reduced to 0.11 at 24 months of age. The maternal permanent environmental effect contributed 16%, 4% and 10% of the total phenotypic variance for WW, 12W and 18W, respectively. Direct-maternal genetic correlations were negative ranging from −0.14 to −0.58. The heritability estimates for reproductive traits were 0.04, 0.00, 0.15, 0.00 and 0.00 for age at first calving (AFC), calving interval in the first, second, and third parity, and pooled calving interval. Selection for growth traits should be practiced with caution since this may lead to a reduction in reproduction efficiency, and direct selection for reproductive traits may be hampered by their low heritability.     

Genetic evaluation of meat quality traits and their correlation with growth and carcase composition in Japanese quail

1. Estimates of heritability, genetic and phenotypic correlations of performance and meat quality traits were obtained in a population of Japanese quail using restricted maximum likelihood (REML) procedures.

2. The heritability estimates for body weight (BW) traits ranged from 0·15 at hatch to 0·42 at six weeks. For carcase composition traits, heritability estimates ranged from 0·12 for carcase yield to 0·26 for abdominal fat yield and for meat quality traits they ranged from 0·18 for drip loss to 0·54 for yellowness of the meat.

3. Negative genetic correlations were found between BW and carcase traits with ultimate pH and drip loss ranging from ?0·01 (BW at hatch) to ?0·40 (skin yield). Redness and yellowness showed negative genetic correlations with BW and carcase traits, whereas the genetic correlations with lightness were positive (from 0·04 to 0·43).

4. Shear force and cooking loss showed positive genetic correlations with carcase, breast, abdominal and skin yield.

5. In conclusion, meat quality traits have the potential to be improved through genetic selection but selection for higher BW and carcase composition may reduce the meat quality of Japanese quail through reducing redness, ultimate pH and intramuscular fat and increasing lightness, shear force and cooking loss of the meat.     

Estimating non-genetic and genetic parameters of pre-weaning growth traits in Raini Cashmere goat

Data and pedigree information used in the present study were 3,022 records of kids obtained from the breeding station of Raini goat. The studied traits were birth weight (BW), weaning weight (WW), average daily gain from birth to weaning (ADG) and Kleiber ratio at weaning (KR). The model included the fixed effects of sex of kid, type of birth, age of dam, year of birth, month of birth, and age of kid (days) as covariate that had significant effects, and random effects direct additive genetic, maternal additive genetic, maternal permanent environmental effects and residual. (Co) variance components were estimated using univariate and multivariate analysis by WOMBAT software applying four animal models including and ignoring maternal effects. Likelihood ratio test used to determine the most appropriate models. Heritability ( \texth_\texta² ) \left( {{\text{h}}_{\text{a}}^2} \right) estimates for BW, WW, ADG, and KR according to suitable model were 0.12 ± 0.05, 0.08 ± 0.06, 0.10 ± 0.06, and 0.06 ± 0.05, respectively. Estimates of the proportion of maternal permanent environmental effect to phenotypic variance (c ²) were 0.17 ± 0.03, 0.07 ± 0.03, and 0.07 ± 0.03 for BW, WW, and ADG, respectively. Genetic correlations among traits were positive and ranged from 0.53 (BW-ADG) to 1.00 (WW-ADG, WW-KR, and ADG-KR). The maternal permanent environmental correlations between BW-WW, BW-ADG, and WW-ADG were 0.54, 0.48, and 0.99, respectively. Results indicated that maternal effects, especially maternal permanent environmental effects are an important source of variation in pre-weaning growth trait and ignoring those in the model redound incorrect genetic evaluation of kids.     

Dominance genetic and maternal effects for genetic evaluation of egg production traits in dual-purpose chickens

• 1.?A study was conducted to study direct dominance genetic and maternal effects on genetic evaluation of production traits in dual-purpose chickens. The data set consisted of records of body weight and egg production of 49 749 Mazandaran fowls from 19 consecutive generations. Based on combinations of different random effects, including direct additive and dominance genetic and maternal additive genetic and environmental effects, 8 different models were compared.

• 2.?Inclusion of a maternal genetic effect in the models noticeably improved goodness of fit for all traits. Direct dominance genetic effect did not have noticeable effects on goodness of fit but simultaneous inclusion of both direct dominance and maternal additive genetic effects improved fitting criteria and accuracies of genetic parameter estimates for hatching body weight and egg production traits.

• 3.?Estimates of heritability (h²) for body weights at hatch, 8 weeks and 12 weeks of age (BW0, BW8 and BW12, respectively), age at sexual maturity (ASM), average egg weights at 28–32 weeks of laying period (AEW), egg number (EN) and egg production intensity (EI) were 0.08, 0.21, 0.22, 0.22, 0.21, 0.09 and 0.10, respectively. For BW0, BW8, BW12, ASM, AEW, EN and EI, proportion of dominance genetic to total phenotypic variance (d²) were 0.06, 0.08, 0.01, 0.06, 0.06, 0.08 and 0.07 and maternal heritability estimates (m²) were 0.05, 0.04, 0.03, 0.13, 0.21, 0.07 and 0.03, respectively. Negligible coefficients of maternal environmental effect (c²) from 0.01 to 0.08 were estimated for all traits, other than BW0, which had an estimate of 0.30.

• 4.?Breeding values (BVs) estimated for body weights at early ages (BW0 and BW8) were considerably affected by components of the models, but almost similar BVs were estimated by different models for higher age body weight (BW12) and egg production traits (ASM, AEW, EN and EI). Generally, it could be concluded that inclusion of maternal effects (both genetic and environmental) and, to a lesser extent, direct dominance genetic effect would improve the accuracy of genetic evaluation for early age body weights in dual-purpose chickens.

     

Direct and maternal (co)variance components, genetic parameters, and annual trends for growth traits of Makooei sheep in Iran

Genetic parameters and genetic trends for birth weight (BW), weaning weight (WW), 6-month weight (6MW), and yearling weight (YW) traits were estimated by using records of 5,634 Makooei lambs, descendants of 289 sires and 1,726 dams, born between 1996 and 2009 at the Makooei sheep breeding station, West Azerbaijan, Iran. The (co)variance components were estimated with different animal models using a restricted maximum likelihood procedure and the most appropriate model for each trait was determined by Akaike’s Information Criterion. Breeding values of animals were predicted with best linear unbiased prediction methodology under multi-trait animal models and genetic trends were estimated by regression mean breeding values on birth year. The most appropriate model for BW was a model including direct and maternal genetic effects, regardless of their covariance. The model for WW and 6MW included direct additive genetic effects. The model for YW included direct genetic effects only. Direct heritabilities based on the best model were estimated 0.15?±?0.04, 0.16?±?0.03, 0.21?±?0.04, and 0.22?±?0.06 for BW, WW, 6MW, and YW, respectively, and maternal heritability obtained 0.08?±?0.02 for BW. Genetic correlations among the traits were positive and varied from 0.28 for BW–YW to 0.66 for BW–WW and phenotypic correlations were generally lower than the genetic correlations. Genetic trends were 8.1?±?2, 67.4?±?5, 38.7?±?4, and 47.6?±?6 g per year for BW, WW, 6MW, and YW, respectively.     

Effect of supplementation of Simada sheep with graded levels of concentrate meal on feed intake,digestibility and body-weight parameters

The experiment consisting of 7 days of digestibility and 90 days of feeding trial was conducted at Wogda (Ethiopia) to determine the effect of supplementation of graded levels of concentrate mix (CM) on feed intake, digestibility, and body weight (BW) change in hay-based feeding of Simada sheep. Twenty-yearling Simada sheep with a mean initial BW of 17.9 ± 0.81 kg (mean ± SD) were used in randomized complete block design arranged into five blocks of four animals. The four dietary treatments that consisted of hay alone (T1), hay +150 g dry matter (DM; T2, low), hay +250 g DM (T3, medium), and hay +350 g DM (T4, high) CM were randomly assigned to each sheep within a block. The CM consisted of wheat bran (WB), noug seed (Guizotia abyssinica) meal and safflower (Carthamus tinctorius) seed meal at the ratio of (2:1:1), respectively. Supplementation with T2 and T3 increased (P < 0.001) total DM and organic matter intake than the control treatment. Overall, supplementation improved (P < 0.001) crude protein intake, digestibility, feed conversion efficiency, BW gain, and profitability compared to the control, whereas sheep on the high than the low and medium level of supplementation performed better in these parameters among the supplemented treatments. From the results of this study, T4 is recommended as the best level of supplementation since it resulted in better nutrient utilization, animal performance, and profitability.     

Supplementation of cottonseed,linseed, and noug seed cakes on feed intake,digestibility, body weight,and carcass parameters of Sidama goats

A digestibility, feed intake, and carcass evaluation experiment using 20 yearling intact male Sidama goats weighing 16.4 ± 0.63 kg (mean ± SD) was conducted in Ethiopia with the objectives to determine feed intake, digestibility, body weight (BW) gain, and carcass parameters. The treatments included feeding natural pasture hay (T1, control) and supplementation with cottonseed cake (284 g—T2), linseed cake (250 g—T3), and noug seed cake (296 g—T4) on dry matter (DM) basis to supply 85 g crude protein (CP) per head per day. Randomized complete block design for feed intake and BW parameters and complete randomized design for digestibility and carcass parameters were used. Hay DM intake was higher (P < 0.01) for T1 than for the other treatments. T3 promoted higher (P < 0.01) DM (29.3 g/kg W^0.75/day) and CP (14.1 g/kg W^0.75/day) intake than T4 (8.9 g/kg W^0.75/day DM and 4.1 g/kg W^0.75/day CP). T3 showed better (P < 0.05) organic matter and CP digestibility than T2. Goats in T3 had higher nitrogen intake (P < 0.01) and retention (P < 0.05) than those in T1. Goats in T2 and T3 showed higher (P < 0.05) daily BW gain and final BW than those in T4 and T1. Goats in T2 and T3 had higher (P < 0.05) slaughter weight, empty BW, hot carcass weight, rib-eye muscle area, and dressing percentage on slaughter weight basis than those in T1. The results showed that T2 and T3 had similar effect on CP intake, daily BW gain, and carcass parameters for growing Sidama goats fed natural pasture hay.     

Estimates of (co)variance components and genetic parameters for growth traits in Sirohi goat

Data were collected over a period of 21 years (1988–2008) to estimate (co)variance components for birth weight (BWT), weaning weight (WWT), 6-month weight (6WT), 9-month weight (9WT), 12-month weight (12WT), average daily gain from birth to weaning (ADG1), weaning to 6WT (ADG2), and from 6WT to 12WT (ADG3) in Sirohi goats maintained at the Central Sheep and Wool Research Institute, Avikanagar, Rajasthan, India. Analyses were carried out by restricted maximum likelihood, fitting six animal models with various combinations of direct and maternal effects. The best model was chosen after testing the improvement of the log-likelihood values. Heritability estimates for BWT, WWT, 6WT, 9WT, 12WT, ADG1, ADG2, and ADG3 were 0.39 ± 0.05, 0.09 ± 0.03, 0.06 ± 0.02, 0.09 ± 0.03, 0.11 ± 0.03, 0.10 ± 0.3, 0.04 ± 0.02, and 0.01 ± 0.01, respectively. For BWT and ADG1, only direct effects were significant. Estimate of maternal permanent environmental effect were important for body weights from weaning to 12WT and also for ADG2 and ADG3. However, direct maternal effects were not significant throughout. Estimate of c ² were 0.06 ± 0.02, 0.03 ± 0.02, 0.06 ± 0.02, 0.05 ± 0.02, 0.02 ± 0.02, and 0.02 ± 0.02 for 3WT, 6WT, 9WT, 12WT, ADG2, and ADG3, respectively. The estimated repeatabilities across years of ewe effects on kid body weights were 0.10, 0.08, 0.05, 0.08, and 0.08 at birth, weaning, 6, 9, and 12 months of age, respectively. Results suggest possibility of modest rate of genetic progress for body weight traits and ADG1 through selection, whereas only slow progress will be possible for post-weaning gain. Genetic and phenotypic correlations between body weight traits were high and positive. High genetic correlation between 6WT and 9WT suggests that selection of animals at 6 months can be carried out instead of present practice of selection at 9 months.     

Effects of 12 hour calf withdrawal on conception rate and calf performance of <Emphasis Type="Italic">Bos indicus</Emphasis> cattle under extensive conditions

Fifty-two multiparous Brahman type cows with reproductive tract scoring (RTS) ≥4 at 45 days post-partum were randomly assigned to two groups of 26 cows each separated into an ad libitum suckling group (C) and treatment group (T). Calves in the T group were separated for 12 h during the night from 45 days post-partum to the onset of the breeding season. Body condition score (BCS) and body weight (BW) were recorded 45 days post-partum, at the start of the breeding season, and at pregnancy diagnosis. Calves were weighed at calving and weaning. Weaning weights were corrected to 205 days. BW and BCS at the onset of the breeding season were similar (p > 0.05) between the experimental groups. Calving to breeding intervals were 93 ± 18 d and 99 ± 22 d for T and C groups, respectively. Calving to conception intervals differed significantly between the groups (111 ± 10 d for T and 133 ± 19 d for C) and a similar result was obtained for the breeding to conception intervals (18 ± 15 d for T and 31 ± 19 d for C). Conception rates were 80% for the T group and 59% for the C group, which correlated better with BW than BCS at the onset of the breeding season. Weaning weights differed (p < 0.05) between C and T groups. From 45 days post-partum to the onset of the breeding season, cows in the T group experienced a positive energy balance (3%) while those in the C group had a negative energy balance (-0.1%). It was concluded that 12 h calf separation at night increases the conception rates and improves the calf weaning weights of Bos indicus beef cattle under extensive production systems in sub-tropical conditions.     

Supplementation with linseed (<Emphasis Type="Italic">Linum usitatissimum</Emphasis>) cake and/or wheat bran on feed utilization and carcass characteristics of Arsi-Bale sheep

Thirty yearling male intact Arsi-Bale sheep with initial body weight (BW) of 15.5 ± 0.21 kg (mean ± SD) were used in 90 days feeding trial, 10 days digestibility trial followed by evaluation of carcass parameters at Bokoji, Ethiopia. The objectives were to evaluate effects of supplementation with linseed (Linum usitatissimum) cake (LSC), wheat bran (WB), and their mixtures at 2:1 and 1:2, respectively on feed intake, digestibility, daily BW gain, and carcass parameters. The five treatments included ad libitum feeding of natural pasture hay (control) and with daily supplementation of 300 g dry matter (DM) sole LSC, 2LSC:1WB mix, 1LSC:2WB mix, and sole WB. Six sheep were randomly assigned to each treatment using randomized complete-block design. Four sheep in each treatment were randomly selected and used for determination of digestibility and carcass characteristics using a completely randomized design. The intake of hay DM was higher (P < 0.001) for the non-supplemented sheep compared with the supplemented ones, but the contrary was true for total DM intake. Sheep in the control treatment lost BW (−1.5 g/day), while the supplemented ones gained 69.0–104.1 g BW/head/day. Digestibility of CP was higher (P < 0.001) for supplemented sheep as a result of higher (P < 0.001) CP intake. Slaughter weight, empty BW, and hot carcass weight were lower (P < 0.001) for sheep in the control treatment compared with the rest. Sheep supplemented with LSC and its mixtures with WB had better (P < 0.001) performance in daily BW gain than sole WB supplemented ones indicating the advantages of using supplements as mixed rations. Moreover, supplementation proved to be profitable, whereas feeding hay alone led to economic loss.     

Effect of protein supplementation on reproductive and productive performance in <Emphasis Type="Italic">Bos indicus</Emphasis> × <Emphasis Type="Italic">Bos taurus</Emphasis> heifers raised in the humid tropics of Costa Rica

In order to evaluate the effect of protein supplementation on the productive and reproductive performance of heifers, 45 Bos indicus × Bos taurus heifers, 673 ± 146 days of age and weighing about 340 kg, were divided into two groups. The control group (n = 23) continued without supplementation, but the supplemented group (SG; n = 22) received concentrate at a rate of 1% BW kg per day. Animals were adapted to the concentrate over a 15-day period and then supplemented for 30 days, after which estrus was synchronized using a progesterone implant. Back fat thickness (BFT) was assessed by ultrasound. The SG had better average daily weight gain than the nonsupplemented group (0.63 ± 0.16 vs. 0.51 ± 0.13 kg/day, P < 0.05) and tended to show a better percentage ovulation (P < 0.10, 77% vs. 57%, respectively). However, this tendency was not reflected in the final pregnancy rates. No differences were observed between groups in dry matter intake and body condition scores. SG with a high BFT (>0.70 cm) showed a better ovulation percentage than those with low BFT (<0.69 cm; P < 0.01). Additionally, the pregnancy rate of supplemented heifers with high BFT tended to be better than heifers with low BFT in this same group (67% vs. 30%, respectively, P < 0.10). It is concluded that protein supplementation improved reproductive performance and that ultrasonography to measure BFT may be used to estimate reproductive performance.