Increased dietary protein in the second trimester of gestation increases live weight gain and carcass composition in weaner calves to 6 months of age.
Genetically similar nulliparous Polled Hereford heifers from a closed pedigree herd were used to evaluate the effects of dietary protein during the first and second trimester of gestation upon foetal, placental and postnatal growth. Heifers were randomly allocated into two groups at 35 days after artificial insemination (35 days post conception (dpc)) to a single bull and fed high (15.7% CP) or low (5.9% CP) protein in the first trimester (T1). At 90 dpc, half of each nutritional treatment group changed to a high- or low-protein diet for the second trimester until 180 dpc (T2). High protein intake in the second trimester increased birth weight in females (P=0.05), but there was no effect of treatment upon birth weight when taken over both sexes. Biparietal diameter was significantly increased by high protein in the second trimester with the effect being greater in the female (P=0.02), but also significant overall (P=0.05). Placental weight was positively correlated with birth weight, fibroblast volume and relative blood vessel volume (P<0.05). Placental fibroblast density was increased and trophoblast volume decreased in the high-protein first trimester treatment group (P<0.05). There was a trend for placental weight to be increased by high protein in the second trimester (P=0.06). Calves from heifers fed the high-protein treatment in the second trimester weighed significantly more on all occasions preweaning (at 1 month (P=0.0004), 2 months (P=0.006), 3 months (P=0.002), 4 months (P=0.01), 5 months (P=0.03), 6 months (P=0.001)), and grew at a faster rate over the 6-month period. By 6 months of age, the calves from heifers fed high nutrition in the second trimester weighed 33 kg heavier than those fed the low diet in the second trimester. These results suggest that dietary protein in early pregnancy alters the development of the bovine placenta and calf growth to weaning.
1School of Veterinary Medicine and Science,University of Nottingham,Sutton Bonington LE12 5RD,UK.
G G
GG
Miguel-Pacheco
2School of Animal Studies,University of Queensland,Gatton,QLD 4345,Australia.
L D
LD
Curtain
1School of Veterinary Medicine and Science,University of Nottingham,Sutton Bonington LE12 5RD,UK.
C
C
Rutland
3School of Veterinary Science,University of Queensland,Gatton,QLD 4345,Australia.
L
L
Knott
4School of Animal and Veterinary Sciences,Charles Sturt University,Wagga Wagga,NSW 2650,Australia.
S T
ST
Norman
3School of Veterinary Science,University of Queensland,Gatton,QLD 4345,Australia.
N J
NJ
Phillips
1School of Veterinary Medicine and Science,University of Nottingham,Sutton Bonington LE12 5RD,UK.
V E A
VEA
Perry
D000818:Animals; D001724:Birth Weight / Q000187:drug effects; D002417:Cattle / Q000254:growth & development / Q000502:physiology*; D004032:Diet / Q000662:veterinary; D018753:Diet, Protein-Restricted / Q000662:veterinary*; D004044:Dietary Proteins / Q000008:administration & dosage*; D005260:Female; D007315:Insemination, Artificial / Q000662:veterinary; D008297:Male; D010920:Placenta / Q000502:physiology; D010929:Placentation; D011247:Pregnancy; D014886:Weaning; D015430:Weight Gain / Q000187:drug effects
D004044:Dietary Proteins
bovine; calf growth; foetal programming; gestation diet