Feed efficiency indicators and hormones related to nutrient metabolism in intensive fattened lambs of sire rams of different sheep breeds in Latvia

I. Trapina¹*, D. Kairisa² and N. Paramonova¹

¹University of Latvia, Institute of Biology, Laboratory of Genomics and Bioinformatics, Jelgava street 3, LV-1004 Riga, Latvia
²Latvian University of Life Sciences and Technologies, Faculty of Agriculture, Institute of Agrobiotechnology, Liela street 2, LV-3001 Jelgava, Latvia
*Correspondence: ilva.trapina@lu.lv

Abstract:

The feed efficiency increase of each sheep indicates its profitability. Production costs and the environmental impact of animal husbandry are reduced as feed efficiency improves. The gastrointestinal tract is a source of hormones and is important in regulating feed intake and nutrient utilization. The study analyses the relationship between feed efficiency indicators and hormone levels in Latvian sheep breeds. After control fattening, blood samples were taken from 76 lambs, representatives of six Latvian breeds, for seven hormonal analyzes and seven feed efficiency indicators. Feed efficiency, Feed conversion ratio (FCR), Relative growth rate, Kleiber ratio (KR), Residual feed intake (RFI), Residual weight gain, and Residual intake were calculated from daily weight gain and amount of dry matter. Interbreed differences and relationships between indicators/hormones were identified. The best scores of feed efficiency were found for the lamb rams of the Dorper breed; the Latvian black-head was the second according to these indicators. The mean FRC for lambs was determined to be 5.13 ± 0.13 kg with a range of
2.98–10.15 kg; the mean KR was 18.11 ± 0.39 with a range of 8.78–26.88; the mean RFI was in the range of -0.51 to 0.42 kg. A statistically significant difference was found between the breeds for all feed efficiency indicators. Biochemical parameters (IGF-1, insulin, and glucose) were found to be in correlation with feed efficiency indicators. Our results show that Latvian sheep breeds differ in fattening performance. To improve breeds without crossing them, subsequent genetic analysis of breed differences is necessary.

Key words:

breeding, fattening, feed efficiency, hormones, Latvian sheep

Comparison of sire rams of the Latvian Dark-Head breed according to feed efficiency indicators as the beginning of genomic breeding research

I. Trapina¹*, D. Kairisa² and N. Paramonova¹

¹University of Latvia, Institute of Biology, Laboratory of Genomics and Bioinformatics, Jelgava street 1, LV–1004 Riga, Latvia
²Latvian University of Life Sciences and Technologies, Faculty of Agriculture, Institute of Agrobiotechnology, Liela street 2, LV–3001 Jelgava, Latvia
*Correspondence: ilva.trapina@lu.lv

Abstract:

In sheep (Ovis aries) farming, feed costs are the largest variable cost component. Breeders are showing an increased interest in breeding sire rams with improved feed efficiency characteristics because of the possibility that the offspring will have a higher value of this indicator. The result shows that for one ram, the progeny indicators tend to be variable. Currently, no marker has successfully explained enough of the variability of feed efficiency that they were used as part of a routine improvement program. The aim is to analyze feed efficiency indicators for lambs of sire rams of Latvian Dark-Head (LT; Latvijas tumšgalve) to identify sire rams producing lambs with potentially higher feed efficiency. Fattening data of 48 lambs from 13 sire rams were analyzed to determine the correlation of feed efficiency parameters. The average weight of lambs at birth was 4.08 ± 0.56 kg, while the average weight gain reached 47.43 ± 3.17 kg with an average fattening period of 73.27 ± 8.90 days. A strong and very strong correlation between the studied indicators of feed efficiency was revealed. The correlation between these indicators and live weight gain over for 60 days indicates their economic importance in meat production. Certain phenotypic and genotypic factors cause the influence on their value. The phenotypic influence may consist of environmental and external signs, but the genotypic influence is at the DNA level, which requires further study.

Key words: