Effect of post-partum breeding interval on conception rates in beef cows

We analyzed date on 1536 fall calving Angus cows to determine the effect of post-partum breeding interval on conception rates in beef cows. Normal fertility was observed for cows showing heat 40 or more days post-partum

Estrus synchronization of cattle in Kansas

In 22 field trials involving 1,692 cattle, we evaluated Lutalyse as an estrus-synchronization agent for both natural mating and artificial insemination. Only 52.7% of the females in all 22 trials were cycling at the start of the breeding season. Both body condition and days postpartum at the start of the breeding season influenced the response to Lutalyse. First-service pregnancy rate in the 2 or 3 days of synchronization was 38.4% for all 453 females bred artificially in 12 trials in northwestern Kansas. The rate was 59%, however, if only females observed to be in heat were counted; but only 24.5% if only those in which no heat was observed were counted

Breed and gender interact to affect the sale price of beef calves sold through video auctions from 2010 through 2014

Citation: McCabe, E. D., King, M. E., Fike, K. E., Hill, K. L., Rogers, G. M., & Odde, K. G. (2016). Breed and gender interact to affect the sale price of beef calves sold through video auctions from 2010 through 2014. Journal of Animal Science, 94, 29-29. doi:10.2527/msasas2016-063The objective of this study was to quantify the effect of the potential interaction of breed and gender on the sale price of beef calves marketed through video auctions while adjusting for all other factors that significantly influenced price. Information on descriptive characteristics of lots of beef calves were obtained from a livestock video auction service. Data were available on 20,007 lots of steer calves and 13,804 lots of heifer calves (2106,181 total steer calves and 1239,645 total heifer calves) that sold in 116 video auctions from 2010 through 2014. All lot characteristics that could be accurately quantified or categorized were used to develop a multiple regression model that evaluated the effects of independent factors on the sale price using a backward selection procedure. A value of P < 0.05 was used to maintain a factor in the final model. Breed description of the calves in the lots was 1 of 19 factors included in the original model and was characterized into 6 groups: English, English crosses (EX), English–Continental crosses (ECX), Black Angus sired out of dams with no Brahman influence (AN), Red Angus sired out of dams with no Brahman influence (AR), and Brahman influenced (BR). Breed and gender of the lot interacted (P < 0.0001) to affect the sale price of calves. Lots of AR and AN steer calves had similar sale prices (P = 0.9540; $379.08 and$378.14 per 100 kg BW, respectively) and sold for significantly higher prices than all other steer breed groups. English cross and ECX steer lots had similar sale prices (P = 0.2588; $376.24 and$374.92 per 100 kg BW, respectively) but were greater (P < 0.05) than BR steer calves ($365.61 per 100 kg BW). Among heifer calves, lots of AR heifers sold for the highest price (P < 0.05;$356.02 per 100 kg BW). The AN heifer calves sold for the second highest price at $345.95 per 100 kg BW, and this price was greater (P < 0.05) compared with ECX ($341.50 per 100 kg BW) and EX heifers ($341.14 per 100 kg BW). Brahman-influenced heifer calves sold for the lowest (P < 0.05) price at$334.64 per 100 kg BW compared with heifers of all other breed descriptions. Breed and gender composition of the lots of beef calves interacted to affect the sale price of calves selling through video auctions. The value of the specific breed composition of beef calves is influenced by gender and may be related to buyers purchasing certain breeds of heifer calves as replacements for the breeding herd

Effect of post-partum breeding interval on conception rates in beef cows

Cattlemen's Fate in '78 is known as Cattlemen’s Day, 1978We analyzed date on 1536 fall calving Angus cows to determine the effect of post-partum breeding interval on conception rates in beef cows. Normal fertility was observed for cows showing heat 40 or more days post-partum

Effect of limited suckling on reproductive performance and milk production of cows and weight gains and suckling behavior of calves

We used 109 Polled Hereford and percentage Simmental cows to evaluate limited suckling as an aid to induce cows to cycle after calving. Cows were allotted to: 1. once daily suckle; 2. twice daily suckle; 3. 48 hr calf removal (just before breeding season); and 4. controls (suckle ad libitum). Half of each group was implanted with Norgestomet 9 days before the breeding season. Limited suckling increased the number of cows showing estrus and conceiving early in the breeding season, and Norgestomet increased the percentage pregnant the first 21 days of the breeding season

Effect of 48-hour calf removal

In three field trials, we removed calves from 187 beef cows for 48 hours at the beginning of the breeding season to determine the effect on the cows' cycling activity, conception rate, and pregnancy rate. When calves were removed, the cows were injected with Lutalyse. Removing calves for 48 hours did not change weight gain or sickness incidence of calves, but neither did it facilitate the cows' rebreeding

Incidence of short estrous cycles after weaning in beef cows

Weaning calves from cows that had not cycled after calving caused a higher percentage of cows to show estrous in the next 25 days than cows suckling calves. However, 78.3% of the nonsuckling cows had short cycles (7-10 days) compared with 16.6% of the cows suckling calves. A short cycle does not appear to be clinically abnormal when estrus occurs with the first ovulation after calving. The percentage of cows having an estrus with the first ovulation, and thus a short cycle, increases drastically when calves are weaned. Although anestrous cows can be induced to cycle by weaning their calves, the first estrus after weaning is relatively infertile

Two semen-thawing procedures compared by competitively mating beef cows

Seventy-five cows were used to compare the fertilizing abilities of sperm packaged in 0.5-ml straws and thawed in warm water to similarly packaged sperm thawed in the inseminating gun. A system of competitive mating provided for inseminating each cow twice. After cows had estrus synchronized, each was artificially inseminated with one straw of Angus semen plus one straw of Simmental semen; semen in one straw was thawed in warm water, the other in the inseminating gun. Calves produced indicated the fertilizing sperm. Of the 20 cows that conceived at the synchronized estrus, 16 conceived to warm water-thawed semen and 4 to semen thawed in the gun. These data indicate that sperm thawed in warm water before breeding were more capable of fertilization when tested in the same cow against sperm thawed in the inseminating gun

Heat synchronization with Alfaprostol

One-hundred eighteen heifers were used to determine the effectiveness of Alfaprostol as a heat synchronization agent. Seventy-nine were injected twice (12 days apart) with 6 mg Alfaprostol per head and 39 were not treated. Twelve to 96 hours after the second injection 88.6% of the treated heifers were in standing heat and 81.4% of those in heat conceived at the first insemination. Eighty-one percent of the 37 untreated heifers in heat the first 21 days conceived at the first insemination. Ninety-one percent of the treated heifers and 89.2% of the untreated heifers conceived within a 50-day breeding period, so Alfaprostol did not affect reproductive performance

Use of Kamar® heatmount detectors in beef cattle synchronized with Lutalyse®

The ability of the Kamar Heatmount Detector to identify cows ready for insemination 80 hours after two Lutalyse injections was tested with 439 beef cows and heifers. The detector was placed on the rump at the second injection and was “read” at insemination. Conception rate from the 80-hour timed insemination for cows with red (activated) and lost detectors was 56.5% compared with 7.6% of the cows with white detectors