Md. Fanning et al., REPRODUCTIVE-PERFORMANCE OF SYNCHRONIZED BEEF-COWS AS AFFECTED BY INHIBITION OF SUCKLING WITH NOSE TAGS OR TEMPORARY CALF REMOVAL, Theriogenology, 44(5), 1995, pp. 715-723
A study was conducted to determine whether presence of the calf during
suckling inhibition influences the response to estrus synchronization
in beef cows. Angus or Hereford cows (n = 89) were administered Syncr
o-Mate-B(R) (SMB), which consisted of a 6-mg norgestomet ear implant (
in situ 9 d) in conjunction with 5 mg of estradiol valerate and 3 mg (
im) of norgestomet. Cows were allotted by breed, body condition, stage
of the estrous cycle, parity and date of parturition to 1 of 3 treatm
ents: 48-h calf removal; ad libitum suckling; or inhibition of sucklin
g with a nose tag for 48 h. Calves were weighed at time of SMB implant
removal, 48 h later and at weaning. Cows were mated via AI approximat
ely 12 h after detection of estrus during a 30-d period after implant
removal followed by a natural service period of 35 d. At 48 h after im
plant removal, calf removal and nose tag calves had lost an average of
3.6 and 0.9 kg, respectively, while the suckled calves gained 1.8 kg
(P<0.01). Mean calf weight at weaning did not differ among treatments.
Synchronized estrous response (within 5 d of implant removal) was not
different among treatments. Pregnancy rate for cows exhibiting a sync
hronized estrus (5 d AI) for calf removal, nose tag and suckled cows w
as 76, 48 and 48%, respectively (P>0.10). Treatment did not affect the
30-d AI or overall 65-d pregnancy rate. In this study, there were no
differences observed in the percentage of synchronized or pregnant cow
s following suckling inhibition by either a nose tag or calf removal.
Transient reductions of calf body weight during the 48-h calf removal
period did occur in both the nose tag and calf removal groups.