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