Reproductive performance of synchronized beef cows as affected by inhibition of suckling with nose tags or temporary calf removal

• Published in: Theriogenology Vol. 44; no. 5; pp. 715 - 723
• Main Authors: Fanning, M.D., Lunt, D.K, Sprott, L.R., Forrest, D.W.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.10.1995
• Subjects: calf weight; estrus; pregnancy rate; suckling manipulation; synchronization; suckling manipulation; synchronization; calf weight; estrus; pregnancy rate
• ISSN: 0093-691X; 1879-3231
• DOI: 10.1016/0093-691X(95)00251-3

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 Syncro-Mate-B ® (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 treatments: 48-h calf removal; ad libitum suckling; or inhibition of suckling 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 approximately 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 implant 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 synchronized estrus (5 d AI) for calf removal, nose tag and suckled cows was 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 cows 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.