Investigation of effects of three candidate genes on leg action and fat deposition traits in pigs (Short communication)

Data from 188 sows were used in the current study to examine the effects of high mobility group AT-hook1 (HMGA1), transcription factor 7-like-2 (TCF7L2) and insulin-like growth factor binding protein 3 (IGFBP3) genes on leg action and fat deposition traits, and further to explore the possible relationships between these genes on both traits. The candidate genes used in the study are known for their roles in fat deposition and growth. Overall leg action was scored on a scale of 1 (good movement) to 9 (leg weakness). Fatness traits included 10th rib backfat (BF10), adjusted 10th rib backfat to 125 kg (adjBF10) and last rib backfat (last BF), measured by ultrasonic imaging approach. The association analyses between single nucleotide polymorphisms (SNPs) and traits were performed using PROC MIXED procedures of SAS. The results showed that the associations between HMGA1, TCF7L2 and IGFBP3 genotypes with fat deposition traits were mostly suggestive in this limited data set. Leg action was also suggestively associated with IGFBP3 gene effects but was not associated with HMGA1 and TCF7L2 genes. Thus, IGFBP3 AA homozygote individuals tended to have had better movements (5.40), and were fatter when compared to GG homozygotes (5.84). The results from this study suggest a possible association between the IGFBP3 gene effects on both leg action and fatness. Therefore, further studies must be carried out in several populations, and using larger data to demonstrate these results conclusively

Environmental-genotype responses in livestock to global warming: A southern African perspective

Global warming will change Southern Africa’s environments from grass dominated vegetation to dry woodland and desert with a vegetation of C4 dominated grasses, whereas the grazing capacity is expected to decline by more than 30%. Animals will also be more exposed to parasites and diseases, mainly as a result of an increase in temperature. An improved understanding of the adaptation of livestock to their production environments is thus important, but the measurement of adaptation is complex and difficult. Proxy-indicators for adaptation, such as reproductive and production traits, can however be used. Adaptation can also be characterized indirectly by describing the production environment in which a breed or population has been kept over a period of time and to which it has become adapted. By describing production environments it will be possible to identify breeds or genotypes that may be adapted to the changed environment of an area. In respect of quantitative breeding technology, fixed and random effects that account for spatial and temporal variation in production environments will have to be identified and physiological breeding value estimations may be necessary. Tools will need to be developed to overlay geo-referenced data sets available onto the different production environments in order to quantify them. Gene or marker assisted selection may play an important role in selection for disease and parasite resistance or tolerance, since it is difficult to measure these traits directly. The development of a high-throughput SNP or gene chip (genomic selection based on Single Nucleotide Polymorphisms) may enhance the utilization of marker assisted selection. Recent research has indicated that the inclusion of information from DNA analysis into BLUP breeding values may result in substantial increases in genetic gain at reduced cost. Strategies that utilizes EBVs derived from genomic analyses (genomic EBVs), together with conventional mixed model methodology, may speed up the process of breeding animals that are adapted to the newly created environment as a result of global warming.Keywords: Global warming, livestock production, adaptation, animal breedin