Section 14 — Animal Genetics and Breeding 



those out of Holstein dams, while those by 

 Guernsey sires were carried 4.8 ± 0.76 days 

 longer than those by Holstein sires. The results of 

 analyses of the data for other generations will be 

 presented. This paper will be submitted to the 

 Journal of Animal Science for publication. 



14.47. Some Observations on Reproduction, Weight 

 Changes under Lactation Stress and the 

 Mothering Ability of British and Crossbred 

 Zebu Cattle in the Tropics. G. H. Lampkin 

 (Kikuyu, Kenya) and J. F. Kennedy (Rock- 

 hampton, Australia). 



Data collected at Belmont on the performance 

 of British, British cross Africander and British 

 cross Brahman females was examined. Details of 

 2871 matings were available. Of the cows mated 

 only 56 per cent of the homebred British cows 

 produced live calves compaied with 77.3 and 

 73.8 per cent from Africander and Brahman 

 crossbred cows respectively. Evidence was found 

 that the low calving percentage for British 

 females was connected with lactation stress, the 

 British cows being frequently unable to maintain 

 weight if two pregnancies occurred in two 

 successive years. Under similar stress crossbred 

 zebu cows could thrive and crossbred Brahmans 

 in particular would normally gain weight. 



Although F-2 calves out of crossbred zebu dams 

 were significantly smaller at birth than contempo- 

 rary crossbred calves obtained from British 

 dams, this ability of crossbred zebu mothers to 

 thrive whilst lactating was not at the expense of 

 their ability to rear their calves. Calves out of 

 crossbred Brahman cows, in fact, grew sig- 

 nificantly faster than crossbred Brahman calves 

 obtained from British dams. Between birth and 

 weaning this difference for males and females 

 was 0.23 and 0.26 lb/day respectively. 



14.48. Serum Transferrin Type and Milk and 

 Butterfat Production in Dairy Cows. G. C. Ash- 

 ton, G. R. Fallon, and D. N. Sutherland 

 (Rockhampton and Brisbane, Australia). 



The serum transferrin types of 225 Jersey cows 

 in 13 herds, and 433 Australian Ulawarra 

 Shorthorn cows in 24 herds, in two regions of 

 Queensland were determined. The effect of 

 transferrin type on lactation length, milk yield, 

 butterfat yield and butterfat percentage was 

 assessed. The results for the two breeds did not 

 differ significantly. Combining the data from 

 both breeds, it was found that on average Tf 



D/D cows had lactations 13.9 days longer than 

 Tf A/ A cows (P < 0.01), and yielded 450 lb 

 (204 kg) more milk (P < 0.01). The results for 

 Tf A/D cows were intermediate. No effect on 

 butterfat percentage was found. 



The proportion of the genetic variance in 

 milk yield due to the transferrin locus was 10.4 

 per cent in the Jerseys and 6.0 per cent in the 

 Australian Ulawarra Shorthorns. This implies 

 that the manipulation of this gene could raise 

 milk yield by about 5.1 per cent in two gener- 

 ations in these herds by quite simple selection. 



The nature of the effect is now known but is 

 not due solely to increased length of lactation. 



14.49. Blood Groups in Czech Brindled Cattle and 

 Czech Large White Pigs. K. Hala, J. Hojnv, 

 J. Matousek and J. Schroffel (Libechoy, 

 Czechoslovakia). 



Besides the formation of antibodies against a 

 great number of new blood factors following 

 isoimmunizations of the Czech Brindled cattle 

 a large number of phenogroups in the B and S 

 systems is characteristic for this breed. 



In 656 bulls and cows of this breed, both 

 phenogroups having been determined by family 

 analysis, 144 phenogroups of the B system and 

 24 of the S system have been proved. In the 

 Czech Brindled breed all types of transferrins 

 have been found. From the above results and in 

 comparison with homogene breeds it may be 

 assumed that the Czech Brindled breed is 

 heterogene. 



In the Czech Large White pig 28 blood factors 

 have been found to this day, the majority of 

 which are classed in 1 1 known genetic systems. 

 Five new blood factors are being studied as to 

 their relationship to genetic systems. 



By electrophoresis on a starch gel between the 

 start and the alpha-fractions a protein fraction has 

 been found, appearing on sexual maturing and 

 lasting till old age. By means of antisera gained 

 by isoimmunization of sows by boar sera a close 

 relationship of this serum protein to the protein 

 parts of the fluid contained in the seminal 

 vesicles of boars has been observed. 



14.50. The Variability of the Number of Vertebrae 

 in Domestic Pigs and Their Relation to 

 Economically Important Criteria. J. K. Hin- 

 richsen (Giessen, Germany). 



The numbers of vertebrae can be of interest 

 for the producers and the consumer of pork, if 



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