Fac­tors af­fect­ing calv­ing dif­fi­culty

Calhoun Times - - Gordon Grown - By Greg Bow­man UGA Ex­ten­sion Agent

This week, I will put on my an­i­mal science hat for a while and dis­cuss fac­tors that come into play when calv­ing dif­fi­culty or dys­to­cia is an is­sue.

It is never fun for a cat­tle pro­ducer to lose a calf at birth or soon af­ter birth. We will use nat­u­ral ser­vice, ar­ti­fi­cial in­sem­i­na­tion and some em­bryo trans­fer in our small herd at home.

Ear­lier in the fall, we lost a calf from one of my daugh­ter’s old show heifers. The now ma­ture cow had al­ways con­ceived AI first time and al­ways calved unas­sisted. We bred her to a na­tion­al­ly­known bull for 2018. In fact, we had a bull calf born on the place the year prior that weighed maybe 65 pounds at birth out of the same sire, but out of a dif­fer­ent cow. The calf we lost was more than dou­ble the size of the calf the pre­vi­ous year.

To­day, I will be shar­ing in­for­ma­tion on fac­tors that af­fect calv­ing dif­fi­culty. The hope is the in­for­ma­tion will help you not run into the same is­sue I had ear­lier in the fall. I will be us­ing a re­vised pub­li­ca­tion by Ted G. Dyer, for­mer UGA Ex­ten­sion an­i­mal sci­en­tist, for ref­er­ence.

Sire se­lec­tion is one of the first man­age­ment de­ci­sions to con­sider in re­gards to calv­ing dif­fi­culty. Keep in mind that there are sires or bulls in each breed that can cause calv­ing dif­fi­culty when bred to cer­tain cows.

Over the years, some breeds of cat­tle have been blamed for calv­ing prob­lems. Just note, that the prob­lems can hap­pen in all cat­tle breeds. Some of the de­ci­sions have to be made based on the sit­u­a­tion such as breed­ing heifers or cows.

You would want to use bulls that are proven in sir­ing low birth weight calves when you are breed­ing heifers. When heifers ma­ture into cows, they can be bred to bulls that may sire larger calves be­cause they should be more ca­pa­ble of de­liv­er­ing safely these off­spring. One tool is also be­ing able to re­view past calv­ing records for sires and even the EPDs — ex­pected prog­eny dif­fer­ences — for the dif­fer­ent bulls. There are EPDs on bulls that will help you look for calf birth weight and calv­ing ease com­par­i­son. EPDs can be used to com­pared bulls within the same breed to the breed av­er­age for that par­tic­u­lar trait.

Keep in mind that there are ac­cu­racy val­ues when look­ing at an EPD for a cer­tain bull such as birth weight EPD that should be con­sid­ered. A young bull may have few re­ported calves to the breed as­so­ci­a­tion so the ac­cu­racy may be low.

In our Cal­houn HERD pro­gram, all of the heifers are bred ar­ti­fi­cially to a na­tion­ally known calv­ing ease bull. When we se­lect that sire, it would be one with high ac­cu­racy for that birth weight EPD trait. EPDs can help take out some of the guess­work in sire se­lec­tion as a tool.

Our in­for­ma­tion states, by us­ing EPDs, pro­duc­ers can eval­u­ate ge­netic po­ten­tial of sires and re­duce the oc­cur­rence of dys­to­cia by low­er­ing calv­ing birth weights and us­ing bulls with a his­tory of high calv­ing ease. Keep in mind there can be some vari­a­tion in each calf crop. Tem­per­a­ture can have a sig­nif­i­cant im­pact on calf birth weight. In fact, en­vi­ron­men­tal fac­tors are re­lated to ap­prox­i­mately 55 per­cent of calv­ing dif­fi­cul­ties. Note, that birth weights can vary from year to year in a herd where the same ge­net­ics and man­age­ment tech­niques are used.

Stud­ies have shown that calves born in the fall weigh less than calves born in win­ter and spring months. This in­crease in fe­tal weight dur­ing the win­ter months is most likely re­lated to the in­creased nu­tri­tion in­take from sup­ple­men­tal feed­ing by the cow, ac­cord­ing to our in­for­ma­tion. As the cow takes in more nu­tri­tion in those months, the nu­tri­ent flow to the fe­tus in­creases so there is in­creased growth rate in the un­born calf. Most fe­tal growth is in the last three months prior to calv­ing.

In re­gards to calv­ing prob­lems, there should be less is­sues with fall calv­ing as com­pared to win­ter and spring. On the flip side, try to stay away from sum­mer calv­ing due to heat and hu­mid­ity stress to the calves. This will re­duce growth rate.

There is data on the ef­fects of dif­fer­ent feed­ing lev­els on dys­to­cia and birth weights. High feed­ing lev­els pre-calv­ing did not show sig­nif­i­cant im­pact on birth weight or dys­to­cia. Now, re­duced feed­ing lev­els did show re­duced cow weight gain, de­creased milk pro­duc­tion, more is­sues with scours and then re­duced preg­nancy rate in the cows.

If grow­ing your own re­place­ment heifers, keep in mind that heifers grown on low nutri­tional di­ets can re­late to an in­crease in dys­to­cia when calv­ing those heifers outs.

Fi­nally, ab­nor­mal calf pre­sen­ta­tions at birth will be a por­tion of calv­ing dif­fi­cul­ties. All cat­tle pro­duc­ers should be­come versed in the calv­ing process. Many pro­duc­ers are able to as­sist cat­tle in dif­fi­cult birth sit­u­a­tions, but note that at times you may need ex­pert help from an large an­i­mal vet­eri­nar­ian.

Keep in mind that the only thing worse than do­ing noth­ing for a calf in an ab­nor­mal pre­sen­ta­tion is to do ev­ery­thing wrong be­fore call­ing the vet.

Greg Bow­man

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