Abstract
This study investigated the effects of
sheep genetics and feed intake on nitrogen isotopic fractionation
(Δ15N) and feed conversion efficiency (FCE;
live weight gain/DMI), using a 2 × 2 factorial design,
with 2 levels of genetic merit for growth (high vs. low)
and 2 levels of feed intake (110 vs. 170% of ME for
maintenance [MEm]). No effect of genetic merit was
detected for live weight gain (P = 0.64), FCE (P = 0.46),
plasma urea nitrogen (P = 0.52), plasma glucose (P =
0.78), and Δ15N of wool (P = 0.45), blood (P = 0.09),
and plasma (P = 0.51). Sheep receiving 170% of MEm
had 175% higher live weight gain (P < 0.001) and 77%
higher FCE (P < 0.001) than sheep receiving 110% of
MEm. There was no difference among treatments at the
beginning of the study for either blood or plasma Δ15N,
but the treatment groups started to diverge in blood and
plasma Δ15N at 21 and 7 d, respectively. Blood, plasma,
and wool samples were enriched in 15N compared with
feed. There was a higher blood, plasma, and wool Δ15N
for the low feed intake group than the high feed intake
group (P < 0.001 in all cases). Across the 4 treatment
groups, higher FCE in sheep was associated with lower
Δ15N for plasma, blood, and wool. Overall, the results
are consistent with the potential of Δ15N as a rapid, lowcost
biomarker of FCE in sheep, despite there being no
effects of genetic treatment on FCE and Δ15N.
| Original language | English |
|---|---|
| Pages (from-to) | 5849 - 5855 |
| Journal | Journal of Animal Science |
| Volume | 93 |
| Issue number | 12 |
| DOIs | |
| Publication status | First published - 2015 |
Bibliographical note
1028921Keywords
- Genetic and nutritional interaction
- Growth potential
- Isotopic discrimination
- Live weight gain