After a Cow Gives Birth When Does Is Come Into Heat Again
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The Cow-Dogie Manager
Livestock Update, Dec 2003
John B. Hall, Extension Animal Scientist, Beef, VA Tech
Offset Estrus Subsequently Calving May Not Be Fertile
Weaning a heavy calf from almost every cow is essential to profitability of the cow-calf operation. Getting a loftier pct of cows bred is the first footstep towards achieving this goal. Nonetheless, nutritional deficiencies, long calving seasons (or no calving flavour), calving difficulty, and a nursing dogie can subtract pregnancy rates. Understanding the basics of cow reproduction is essential in developing management strategies to improve reproduction. Over the side by side few months, this column will concentrate on dissimilar aspects of beef cow reproductive biology equally well as techniques to ameliorate reproduction.
Post-calving (postpartum) anestrous
Afterward calving, information technology takes 60 to 90 days for cows to resume cycles. This period is chosen postpartum anestrous. In first calf heifers, postpartum anestrous lasts longer than mature cows. Information technology normally takes xc to 120 days for offset calf heifers to resume cycles.
Biologically postpartum anestrous makes sense for several reasons. Outset, heat cycles and reproduction take a great deal of nutritional energy. Nonetheless, immediately after calving the most important use of nutrients is to brand milk for the calf, so shutting off the reproduction system makes sense. Second, because pregnancy lasts ix months in cattle getting pregnant "too shortly" would upshot in calves being born earlier each year. Dorsum when cattle were wild, the delay in rebreeding was of import to ensure calves were born when weather and grass were favorable to calf survival. Also, it gives the reproductive organisation fourth dimension to repair and compress back to its normal size after calving. Finally, the interplay of hormones that cause estrous cycles has been shut off for ix months and it have time to bring these hormones back to normal levels.
The length of the postpartum interval is influenced by several factors the most important are nutrition and presence of the calf. From fourth dimension to time, this column has discussed the part of these two factors in beef moo-cow reproduction and we will revisit these in the coming months.
Cycles resume � false starts?
Subsequently the showtime heat, nearly 25 to 30% of cows have a "brusque wheel". A normal bicycle lasts 19 to 23 days in beefiness cattle. Nevertheless, curt cycles concluding only 12 to xv days. During short cycles progesterone, the hormone that supports pregnancy, does non stay elevated for enough days to allow implantation to occur.
In lxx to 80% of beef cows, in that location is a brief (2 to 8 solar day) increment in progesterone that occurs before the kickoff oestrus (Effigy ane). This increment in progesterone appears to be necessary part of the resumption of normal cycles. A recent study reported that 81% of cows that had a rising in progesterone before start oestrus had cycles of normal length whereas only 36% of cows that did not have increased progesterone had normal cycles (Looper et al., 2003). Cows that accept short cycles do non get pregnant.
The rise in progesterone before the first heat "primes the pump" and then that the starting time cycle after the first postpartum estrus is of normal length. It appears that progesterone induces production of the hormones from the brain that cause follicular development and ovulation. Also, the rise in progesterone may be important to synchronizing egg evolution, heat and ovulation.
What does it mean to the average beef producer?
Well-nigh chiefly, knowing that cows need to take either a rise in progesterone or a short bicycle before a fertile heat will occur ways that cows demand to have enough time between calving and the start of the convenance flavour for these normal processes to occur. Then, calving seasons need to exist curt enough to allow cows time to recuperate after calving. This means sixty to 90 twenty-four hours calving seasons.
Besides, administering progesterone in the form of estrous synchronization products (MGA or CIDRs) volition "bound start" non-cycling cows and reduce the incidence of short cycles. The MGA (0.5 mg/ cow/mean solar day) can be used in natural service herds if it is fed for only 7 to x days. This volition bound start cows without synchronizing them also tightly for the bull to handle. Use of MGA or CIDRs in late calving cows is a practiced way to decrease the length of the breeding/calving season.
Adjacent month: Pre-calving a critical time
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Source: https://www.sites.ext.vt.edu/newsletter-archive/livestock/aps-03_12/aps-278.html
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