Abstract
This study aimed at investigating the effects of decreasing crude protein (CP) in diets
with constant rumen undegradable protein (RUP) content on dry matter (DM) intake,
growth, feed efficiency (FE) and blood parameters in calves in a randomized complete
block design. Dietary treatments included: (a) a calf starter containing 200 g/kg
CP (62 g/kg RUP, based on DM), (b) a starter containing 180 g/kg CP (65 g/kg RUP,
based on DM) and (c) a starter containing 160 g/kg CP (65 g/kg RUP, based on DM).
A total 42 newborn male and female Holstein calves were fed 8 L milk/day until day
45, after which they were weaned and continued the experiment until day 75. Solid
feed intake and total DM intake were measured daily, and body weight and skeletal
growth parameters including withers height and heart girth were recorded weekly.
Blood samples were collected on days 45 and 75. Solid feed intake, total DM intake,
weaning weight, average daily gain from birth to weaning and from birth to 75 days,
final weight and FE were not affected by the experimental treatments. In addition,
skeletal growth parameters were similar among groups. Glucose concentration was
similar among treatments; however, calves fed the starter containing 160 g/kg CP
had significantly lower plasma concentrations of albumin and urea nitrogen compared
with those fed starters containing 180 and 200 g/kg CP. These results indicate
that CP level in the calf starter could be decreased to 160 g/kg DM if RUP levels stay
at 65 g/kg DM, without negatively affecting feed intake and calf performance.
K E Y W O R D S
calf performance, heat-treated soybean meal, protein, rumen degradability
Publisher:
Journal of Animal Physiology and Animal Nutrition: Volume 104, Issue 5
Qurtiles : Q1
IMPACT FACTOR: 3.29
Country: UK
Target animal: Dairy Cow
Product under study: Yasminomax