TITLE:
Methionine and Threonine Requirements of Dutch Rabbits Fed under a Cecotrophy Prevention Program
AUTHORS:
Yumi Abe, Hitoshi Muramatsu, Seizi Sukemori
KEYWORDS:
Dutch Rabbit, Methionine, Threonine, Requirement, Plasma Level
JOURNAL NAME:
Open Journal of Animal Sciences,
Vol.9 No.2,
March
20,
2019
ABSTRACT: It is suggested that the difference in body size
between domestic-type rabbits and small pet-type rabbits results in different
nutrient requirements. The nutritional requirements of pet rabbits have been
assessed, although such assessments require evaluation throughout the rabbit
life span. The present study was conducted under a cecotrophy prevention
program with young and adult rabbits. Six male Dutch rabbits were housed
individually in a dormitory-type cage, and they were randomly fed graded levels
of dietary methionine and threonine, at ratios of 4:0, 3:1, 2:2, 1:3, and 0:4
mixed with two types of feed, 4:0 and 0:4. Four days after switching diets and 4 hrs after starting morning
feeding, approximately one milliliter of blood was collected from the vein of
the ear. Free amino acid concentrations in the plasma were determined with a
high-speed amino acid analyzer. Plasma concentrations of methionine and
threonine compared to dietary methionine and threonine levels are shown in
young rabbits. The plasma concentration of methionine remained constant at a
low level and then increased linearly. The intersection was estimated as 0.16
g/d. In the same manner, the intersection of the plasma threonine value was
estimated as 0.27 g/d. These values were calculated as 0.27% and 0.47% of the
diets, respectively. In the case of adult rabbits, the baseline was not
obtained for dietary methionine and threonine levels. The methionine
requirement was estimated as 0.11 g/d. The threonine requirement was estimated
as 0.22 g/d.
These values were calculated as 0.15% and 0.30% of the diets, respectively. In comparison with young and
adult rabbits, both methionine and threonine showed a low baseline level in
young rabbits, while their variations in plasma levels of adult rabbits were not determined. The
requirement of both amino acids in young rabbits is higher than that in adult
rabbits. The dietary values of both amino acids in young rabbits were also
higher than those in adult rabbits. Small pet-type adult rabbits required lower amino acid levels than
domestic-type rabbits.