Summary A total of 57 Indian Sahiwal (Bos indicus) cattle and 53 Murrah and 19 Nili‐Ravi (Bubalus bubalis) buffalo were screened using PCR/RFLP to detect the following alleles at growth hormone (GH) and prolactin (PRL) loci: leucine/valine (L/V) for GH/AluI (amino acid 127), (+/+) for GH/MspI (intron III), and A/B for PRL/RsaI (amino acid 103). Among Sahiwal cattle, gene frequencies were 0.96/0.04 (GH/AluI), 0.86/0.14 (GH/MspI), and 0.49/0.51 (PRL/RsaI). In buffalo, animals of both breeds were homozygous for GH loci (LL, ++). In Egyptian buffalo, 11 samples were also monomorphic, indicating that monomorphism at these two loci may be a species characteristic of buffalo. PRL/RsaI frequencies were 0.93/0.07 and 0.84/0.16 in Murrah and Nili‐Ravi buffalo, respectively. Zusammenfassung Bei insgesamt 57 indischen Sahiwal (Bos indicus) und 53 Murrah und Nili‐Ravi Büffeln (Bubalus bubalis) wurde mit PCR/RFLP auf die folgenden Polymorphismen des Wachstumshormon‐ (GH) und Prolaktingens (PRL) untersucht: L/V für GH/AluI (Austausch Leucin/Valin der Aminosäure 127), (‐/+) für GH/MspI (Intron III) und A/B für PRL/RsaI (Aminosäure 103). Bei Sahiwal waren die Genfrequenzen 0,96/0,04 (GH/AluI), 0,86/0,14 (GH/MspI) und 0,49/0,51 (PRL/RsaI). Bei den Büffeln waren die Tiere beider Rassen — wie auch 11 ägyptische Büffel — homozygot für die GH Loci (LL, ++), was darauf hinweist, daß Büffel monomorph an beiden Schnittstellen sind. Die Frequenzen für PRL/RsaI betrugen 0,93/0,07 und 0,84/0,16 bei den Murrah and Nili‐Ravi Büffeln.

A leucine/valine substitution of growth hormone amino-acid 127 was genotyped in 221 Bavarian Simmental bulls by PCR/RFLP. Gene frequencies for leucine (L) and valine (V) were 0.68 and 0.32, respectively. Breeding values for meat traits were significantly different between genotypes. The heterozygous genotype LV was superior to LL and VV in both carcass gain (p < 0.01) and meat value, an index which includes carcass gain and classification score (p < 0.05). In relation to classification score, genotype VV was significantly better (p < 0.05) than LV and VV. No effects on milk breeding values were apparent even though those of milk composition approached significance. ZUSAMMENFASSUNG: Einfluß von Wacbstumshormon-Genotypen auf Zuchtwerte von Fleckviehbullen Ein Polymorphismus der Aminosäure 127 des bovinen Wachstumshormones wurde bei 221 bayerischen Fleckviehbullen mit PCR/RFLP genotypisiert. Die Genfrequenzen für Leucin (L) und Valin (V) betrugen 0.68 und 0.32. Es bestand ein signifikanter Einfluß auf die Fleischzuchtwerte. Der heterozygote Genotyp LV war in den Merkmalen Nettozunahme (p < 0.01) und Fleischwert (p < 0.05) den Geno-typen LL und VV signifikant überlegen. Im Merkmal Handelsklasse war Genotyp VV signifikant günstiger als LV und LL. Es konnten keine Beziehungen zu den Milchzuchtwerten beschrieben werden, allerdings grenzte der Einfluß auf Milchzusammensetzung an statistische Signifikanz.

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A leucine/valine substitution at amino acid position 127 was identified by the polymerase chain reaction and restriction fragment length polymorphism in the bovine growth hormone gene. Genotyping was performed in 84 AI bulls of three different breeds, in which plasma concentrations of growth hormone (GH) and insulin-like growth factor I (IGF-1) were also measured. Gene frequencies of variants L (leucine) und V (valine) were 0.80/0.20 (Black and White), 0.90/0.10 (Brown), 0.71/0.29 (Simmental). Hormone concentrations were measured during different physiological conditions (normal feeding, fasting, realimentation) in the majority of animals. Generally, genotype LL was associated with higher concentrations of GH than LV. This difference was significant in Black and White bulls (P < 0.05). In contrast, IGF-1 concentrations were higher in LV than in LL animals. This was most pronounced in mature, realimented Simmental bulls. We conclude that the various GH alleles influence the circulating concentrations of GH and IGF-1.

We screened 57 Sahiwal cattle (Bos indicus) and 53 Murrah, 19 Nili-Ravi and 11 Egyptian buffaloes (Bubalus bubalis) to detect the polymorphisms at kappa-casein (CSN3) gene using the polymerase chain reaction (PCR). CSN3 A and B alleles were identified by PCR-RFLP using the restriction enzymes that detect the underlying nucleotide changes at codon 136 (Taql) and at codon 148 (HindIII or HinfI) in cattle. The frequency of CSN3 B allele in the Sahiwal cattle was estimated as 0.16 with no homozygous BB animal. Using the same set of primers as used in the Sahiwal cattle, a part of exon IV of buffalo CSN3 gene was amplified, but restriction enzyme analysis using HindIII/HinfI and TaqI did not reveal any polymorphism. However, DNA sequencing of the amplified fragment (GenBank Acc. No. U96662) revealed one polymorphism at codon 135 (ThrACC -->I1eATC) in buffalo; the frequencies of 135 Thr/Ile alleles were estimated as 0.88 and 0.12, respectively.

Lines of mice selected for many generations for high or low growth in several laboratories around the world have been collected, and from these, inbred lines are being developed by recurrent full-sib mating in Edinburgh. There are seven high selected lines and four low lines (each low line is from the same base population as one of the high lines), and the histories of each are summarized. Mean body weight of males at 70 days of age in the Edinburgh laboratory in the heaviest inbred line (77 g) is 4.8-fold higher than in the lightest line (16 g), and 1.9-fold higher than in the least extreme high line (41 g). Litter size, food intake, and fat content also differ substantially. These inbred extreme selected lines are a uniquely valuable resource for QTL or gene mapping, candidate gene identification, and elucidation of epistatic effects.

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