Christian F. Gall

Crossbreeding for dairy production in the lowland tropics of Kenya. II. Prediction of performance of alternative crossbreeding strategies

The predicted performance of nine crossbreeding strategies for milk production and reproductive traits and cow live weights (LW) were compared. The strategies were selected because of their superiority to many others. The data were from crosses of Ayrshire (A), Brown Swiss (B), Friesian (F) and Sahiwal (S) cattle. Performances were predicted from the results of a genetic model based on additive breed differences, dominance and additive 3 additive interaction effects for the breeds involved. The crossbreeding strategies were: first cross (F3 S), two-breed rotation (AS) , three-breed rotation (BFS) Rot Rot and two- (F and S), three- (B, F and S) and four-breed synthetic breeds based on equal and unequal contribution of the foundation breeds. The mean lactation milk yield (MY) of production systems based on F 3 S, (AS) or (BFS) cows Rot Rot and in which replacements are raised from within, was also predicted under varying number of calvings (NL) and reproductive performance (RP). At the individual cow level, differences in the predicted MY between the F 3 S cross, three-breed rotation and the synthetic breeds were small. While the F 3 S cross was superior to the two-breed rotation for predicted MY, its performance was similar for MY expressed per unit of metabolic weight. Among the synthetic breeds, differences in MY expressed per unit metabolic weight were small. At the production system level, it was predicted that MY for production systems based on F 3 S cows become superior to those based on (AS) cows only at a NL higher than 4 and Rot were inferior to those based on (BFS) . This study shows that F 3 S cows were closely rivalled by the (BFS) and the Rot Rot synthetics. Its inferiority was particularly shown at the production system level. It is concluded that the first cross is not generally the best suited for dairy production systems in the tropics. There is the need to promote greater awareness of the potential of synthetic breeds and to formulate strategies for developing and exploiting them.

Economic evaluation of crossbreeding for dairy production in a pasture based production system in Kenya

Data on accumulated life performance of crosses of Ayrshire (A), Brown Swiss (B), Friesian (F) and Sahiwal (S) cattle collected over a 21-year period from a dairy ranch in the lowland tropics of Kenya were analysed to estimate additive and non-additive genetic effects on economic traits. These were used to predict and compare, first, performance of cows under nine crossbreeding strategies and, second, the performance of the production systems when applying the strategies that included maintaining the purebred S dams and bulls required for the production of crossbreds. Performance was predicted from parameters of a genetic model based on additive-dominance and additive×additive interaction effects for the following strategies: first cross (F×S), two-breed rotation (AS)Rot, three-breed rotation (BFS)Rot and two- (F and S), three- (B, F and S) and four- (A, B, F and S) breed synthetic (Syn) breeds based on equal and unequal contributions of the foundation breeds. The sensitivity of predicted performance at the cow level to variation in economic parameters was also investigated. For profit per day of productive herdlife (PLD), the B and F additive breed effects were not significantly different from that of A. The additive breed effect for S was negative and significant (P<0.01) indicating that it was inferior to the Bos taurus for PLD. Dominance effects for PLD in the crosses A×S and B×S were positive and significant (P<0.05). The additive×additive interactions were negative and significant in all the crosses. At the individual cow level, predicted PLD would be lowest in (ABFS)Syn and highest in F×S. The (3/4F 1/4S)Syn would be the second-best strategy giving 90% of the expected F×S profit, while (FS)Syn would give 87%. At the production system level, systems based on F×S cows were superior to those based on the rotations at all level of number of calvings (NL) and would be superior to those based on the two-breed synthetics only at a NL higher than 4. Variation of costs and prices greatly affected predicted economic benefit but not the ranking of strategies. The absence of significant differences in the additive breed effects of the B. taurus breeds for PLD showed that comparable economic benefits were derived by use of any of the three breeds for continuous crossbreeding with the S in a production system with management achieving 3000 kg lactation yields. It is also expected that the economic benefits from the development of two-breed synthetic breeds based on A, B or F would also be comparable in production systems achieving lower yields (e.g., in many smallholder units).

A study on the Changthangi pashmina and the Bakerwali goat breeds in Kashmir: I. Analysis of blood protein polymorphisms and genetic variability within and between the populations

Abstract Blood samples of 483 Pashmina goats and 392 Bakerwali goats were taken from the Ladakh and Jammu provinces, respectively, for characterisation of the breeds by polymorphic enzymes and proteins. Furthermore, the sex, age, body weight and hematocrit of both breeds and the pashmina yield of Pashmina goats were recorded. Polymorphisms of 12 enzymes and proteins (albumin (Al), alkaline phosphatase (Alp), amylase (Amy), NADH-diaphorase 1 (Dia1), vitamin-D-binding protein (Gc), haemoglobin (Hb), hemopexin (Hpx), nucleoside phosphorylase (Np), malic enzyme (ME), phosphohexose-isomerase (PHI), transferrin (Tf), X-protein (X)) in blood plasma and hemolysate were determined using gel electrophoresis. Out of 12 protein systems, 10 were found to be polymorphic. In four systems (Al, Amy, Dia1, Hpx) new phenotypes were detected. To estimate the genetic variability within breeds, the degrees of heterozygosity, deviations from the Hardy–Weinberg-equilibrium (HWE) and FIS-, FST-, and FIT-values were estimated. In comparison with literature data both breeds show slightly higher variability than other goat breeds, with degrees of heterozygosity ranging from 15 to 25% and 24 to 26% in the Pashmina and Bakerwali goat populations, respectively, and the percentage of polymorphic loci ranging from 50 to 67%. On the other hand, a decrease of variability at some loci can be observed in both breeds. Deviations from HWE in combination with a deficiency of heterozygote genotypes were observed in all sub-populations apart from the Pashmina sub-population ‘Likir’. Genetic differences between the goat breeds could be quantified through calculation of Nei’s genetic distances ranging from 0.002 to 0.080. With exception of the Pashmina sub-population ‘Likir’, lower distance values were found between sub-populations within the respective breeds.

Protein polymorphisms in the blood of German improved fawn and Boer goats

Abstract Polymorphisms of five biochemical systems (adenosine deaminase, alkaline phosphatase, amylase, phosphoglucomutase, transferrin) were examined in the blood of two goat breeds using starch gel, agarose gel and polyacrylamide gel electrophoresis. Three different phenotypes could be separated in adenosine deaminase for the first time. However, our separation method has to be improved concerning differentiation of A and B bands. In alkaline phosphatase one band was found in addition to the phenotypes already known. In amylase no polymorphism could be found within the breeds. Nevertheless, the phenotypes observed in the two breeds differed in the way that in Boer goats the faster and in German Improved Fawn goats the slower migrating phenotype was found. In transferrin the three phenotypes AA, AB, BB were found in both breeds with the corresponding alleles Tf A and Tf B . Methods for alkaline phosphatase, amylase and transferrin are suitable to investigate polymorphic systems in goats on a large scale. In phosphoglucomutase the PGM-1 locus, which has not been described in goats yet, was found to be polymorphic with up to four bands. Additional experiments for PGM should clear up the mode of inheritance in goats.

Pre-harvest pearl millet tillers and leaves as animal food.

Feeding experiments with pre-harvest tillers and leaves of 2 varieties of pearl-millet were conducted on a research station in semi-arid Mali. Tillers were harvested at 45 to 65 days after sowing (DAS) and fed green. Leaves were harvested at 65 to 85 DAS and fed to sheep or cattle green or after 8 months conservation as hay or as silage.Intake of organic (IOM) was higher for green leaves than for tillers, showing no difference for the 2 varieties used. In vivo digestible organic matter (DOM) was highest for tillers in both varieties. Nutritive value of tillers and green leaves met the quality criteria for a maintenance diet of sheep.During conservation of millet leaves, the reduction in nutritional value was less with hay than with silage. Small amounts of silage offered as a supplement to rice straw helped to meet maintenance requirements for metabolizable energy. Conserved as hay, a quality forage was obtained which on an economic scale compensated for grain yield losses when fed to selected animals.

Herdendynamik und Herdenproduktivität im Stationären Gleichgewicht: Algorithmen, Anwendungsgebiete, Erweiterungsaussichten

Drei methodische Ansatze der Modellierung von Herdendynamik und Herdenproduktivitat von Tierproduktionssystemen werden kurz beschrieben und vergleichend besprochen. Anwendungsgebiete und kunftige Erweiterungen werden diskutiert.

Simulating Animal Production Systems

A brief overview on the rationale, design and methodological problems of simulation models of animal production systems is given. Future applications as a complement to macro-economic sector modelling in the context of revised agricultural policies are discussed.