(1) The study was conducted to estimate the heritability, genetic correlations and breeding values of laying hens based on individual records and group mean records. (2) Records of two pure lines from a commercial breeding programme of White Leghorns from three generations housed in single cages and in group cages were used. A total of 8483 and 8817 individual records of lines A and D, respectively, and a total of 1358 (line A) and 1161 (line D) group mean records were analysed. (3) An animal model using Restricted Maximum Likelihood (REML) was used to estimate variance components of individual records. Group mean records were analysed using the sire model, taking heterogeneity of error variance and correlated residual effects into account. Breeding values of sires were estimated based on the BLUP method using a multivariate sire model. Spearman Rank correlations were used to compare sire breeding values estimated from individual records and from group mean records. The traits studied were monthly egg production, cumulative production and egg weight. (4) Heritability estimates based on individual records were higher than from group mean records. Heritabilities for cumulative production records were higher than for monthly production, based on individual as well as group mean records. The estimates of genetic correlations between monthly egg production and cumulative production were moderate to high. Egg production and egg weight recorded individually were highly genetically correlated with those recorded on group means. Sire breeding values estimated from individual records showed high correlations with those from group mean records. (5) Differences in the ranking of sire breeding values estimated from individual vs group mean records were negligible, indicating that no genotype x environment interaction exists. Selection based on individual performance records of laying hens housed in single cages could give a good response on performance of laying hens housed in group cages. Cumulative egg production over periods 1 to 6 is the best trait for the selection programme.

PENDAHULUANKandang merupakan bangunan yang digunakan sebagai tempat tinggal ternak yang memiliki fungsi primer dan fungsi sekunder. Fungsi primer kandang berarti kandang sebagai tempat tinggal ternak yang dapat melindungi ternak dari pengaruh buruk cuaca, iklim dan gangguan binatang buas. Fungsi sekunder kandang berarti kandang sebagai tempat peternak bekerja untuk menjalankan kegiatan pemeliharaan ternak. Sarjana (2007)

Abstract. The present study was conducted to estimate the heritability and genetic correlation of monthly egg production and egg weight of 2 lines White Leghorn hens in single and group cages. A total of 2289 records (line A) and 2596 records (line D) from single cages, 518 and 541 records (for line A and D, respectively) from group cages, were analysed. (Co) variance components of single cage data were analysed using the programme VCE4 applying the REML method and a multiple trait animal model. An EM-algorithm was used to obtain (co) variance components for group cage data. Genetic correlations between single and group cages were analysed using the programme VCE4 based on sire model. Heritability estimates for monthly egg production in single cages ranged from 0.08 to 0.44 (line A); 0.04 to 0.43 (line D) and those for group cages were 0.02 to 0.42 (line A); 0.02 to 0.19 (line D). Egg weight was highly heritable for single and group cages (heritability = 0.25 to 0.54). The genetic correlations between monthly and cumulative egg production were 0.25 to 0.95 (line A); 0.26 to 0.86 (line D) for single cage and 0.24 to 0.84 (line A); 0.26 to 0.96 (line D) for group cage. Cumulative egg production in single cage were highly correlated with those of group cages (0.89 and 0.63, respectively for line A and line D). Single cage records gave higher estimates of genetic parameter than group records. However, the trend of estimates is almost the same. High genetic correlations were found between single- and group cages in most of the production periods.

Abstract. This research was conducted to evaluate the performance of female Madura cattle in three districts of Madura Island (Sampang, Pamekasan, and Sumenep), known as breeding areas for purebred Madura cattle. Vital statistics of 1,040 female Madura cattle at 24 and 30 months old in Sampang, Pamekasan, and Sumenep district were measured and analysed. Mean of Body weight, chest girth, body length, and wither height of female Madura cattle at 24 months old were 191.7±17.6 kg, 133±3.0 cm, 124.0±2.1 cm, 115.7±2.9 cm, respectively, and those at 30 months old were 209.4±23.6 kg, 138.2±4.5 cm, 125.7±2.6 cm, 116.7±3.4 cm, respectively. The body weight, chest girth, body length of female Madura cattle at 24 and 30 months old in Pamekasan district (216.6±26.5 kg, 135.2±6.1 cm, 125.4±3.9 cm, and 238.0±28.5 kg, 141.5±6.7 cm, 127.9±3.5 cm, respectively) showed the highest value compared to those in Sampang and Sumenep district. Phenotypic correlation between vital statistics and body weight at 24 and 30 months old ranged between -0.43 to 0.90. Chest girth showed the positive highest correlation with body weight of female Madura cattle at 24 months old (0.24) and at 30 month old (0.90). It indicated that chest girth could be used as estimation parameter for body weight in female Madura cattle.

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