Exposure of prepubertal beef bulls to cycling females does not enhance sexual development

The objective of this study was to determine whether continuous, long-term, fenceline exposure of prepubertal beef bulls to cycling beef females reduced age at puberty and influenced the percentage of bulls that passed an initial breeding soundness examination (BSE). Bulls (Angus, N = 37; Simmental, N = 22; Hereford, N = 10; Simmental x Angus, N = 8) averaging 202 ± 21.5 d of age were given either continuous fenceline and visual exposure to cycling females (Exposed: N= 41) or no exposure (Control: N=36). Estrus was induced in cycling beef females so at least 3 females were in standing estrus each week during the 182 d of exposure to bulls. Scrotal circumference (SC), body weight, and blood samples were collected every 28 d. When bulls had SC ≥ 26 cm, semen samples were obtained monthly via electroejaculation until puberty was achieved (≥ 50 x 106 sperm/mL with at least 10% progressive motility). Behavioral observations were conducted twice monthly, once when females were in estrus and once during diestrus. Homosexual mounting, flehmen responses, and number of times near penned females were recorded for each observation period. Breeding soundness examinations were conducted when bulls averaged 364 ± 21.5 d of age. Normal sperm morphology of at least 70% and sperm motility of at least 30% were required to pass the BSE. Age, body weight, and SC at puberty did not differ between Exposed and Control bulls (320 ± 28 d and 311 ± 29 d; 466.2 ± 12.2 and 437.7 ± 13.5 kg; and 34.4 ± 2.5 cm and 34.9 ± 2.5 cm, respectively). Percentage of bulls passing their initial BSE did not differ between treatments (Exposed: 87.8%, Control: 75.0%). Treatment, month, and female estrous stage interacted (P = 0.05) to affect the number of mount attempts and flehmen responses. Exposed bulls entered the cow area more times (P < 0.001) during estrus than diestrus in months one, two and three. We concluded that bulls given 3 continuous, long-term, fenceline exposure to cycling beef females do not have enhanced sexual development

Prolonged Elevated Concentrations of Estradiol Do Not Affect Conception Rates in Beef Cattle

Following treatments causing either prolonged elevated concentrations of estradiol associated with development of persistent follicles or inhibited elevated concentrations of estradiol and development of persistent follicles, conception rates were compared. Beef females received either four norgestomet implants for 9 days (day 0 = treatment initiation; n=59) or one norgestomet implant for 7 days and three additional norgestomet implants for 2 days (n=60). All implants were removed on day 9 followed by estrous detection and AI for 7 days. Treatment and day interacted to affect estradiol concentrations from day 0 to day 9 with elevated estradiol in females treated with one norgestomet implant for 7 days. Conception rates to AI were similar across treatments. Prolonged elevated concentrations of estradiol associated with development of persistent ovarian follicles do not affect fertility when persistent ovarian follicles are not allowed to ovulate

Kansas State University Feedlot Boot Camp and Teaching Program: Growing Student Interest and Engagement in the Feedlot Industry

Objective:Our objectives were to summarize the development and structure of the Kansas State University Feedlot Boot Camp and Teaching Program and examine student interest in careers in the feedlot industry after participation. Study Description:Since 2019, 95 Kansas State University College of Agriculture undergraduate students participated in the Feedlot Boot Camp Program. The aim was to develop students’ knowledge, skills, and professional relationships in feedlot management to help meet the critical need for trained professionals in the industry. Components are a four-day Feedlot Boot Camp, student presentations, animal health day, and an optional feedlot internship. Students who completed all components earned a $2,500 scholarship. Results:A total of 163 undergraduate students applied to participate in the program in its first five years. Of those applicants, 95 were selected to participate in the Feedlot Boot Camp Program. In surveys following the completion of the Boot Camp portion of the program, over 96% (91/95) of student participants agreed with the statement, “My interest in pursuing an internship and (or) career in the feedlot industry grew as a result of this Boot Camp.” Approximately 45% of participants proceeded to partic­ipate in feedlot internships or entered full-time jobs working in a feedlot six months after completing the Boot Camp. The Bottom Line:The Feedlot Boot Camp program has made progress in growing student interest and awareness of career opportunities in the feedlot industry and fostering communication between employers and prospective employees

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

Post-Weaning Feed Intake and Performance of Bulls Developed in an Automated Feed Intake Management System

Objective:Our objectives were to compare expected and observed dry matter intake (DMI) and average daily gain (ADG) using modeled nutrient requirement equations, and to evaluate change in DMI over time of beef bull calves fed in an automated feed intake system. Study Description:Feed intake and performance data from purebred Angus, Hereford, and Simmental bull calves across two calf crops [birth years 2021 (n = 40) and 2022 (n = 37)] were utilized for this analysis. Projected DMI and ADG were calculated for each group of bulls by year on an individual basis using the Growing Bull module of the Excel-based Beef Ration and Nutrition Decision Software (BRANDS) formulation program (Iowa State University, Ames, IA). These predicted figures were compared to the Insentec intake data and analyzed via SAS. Results:In 2021–2022, a strong positive correlation (r= 0.78,P\u3c0.01) was observed between actual and predicted DMI. There was a highly correlated (r= 0.84,P\u3c0.01) relationship for the observed and predicted DMI for 2022–2023 as well. Actual ADG for both years was markedly higher than predicted. This result supports that BRANDS more accurately predicts DMI compared to ADG, and that substantial individual intake variation exists. The Bottom Line:DMI increases over time as days of test period increase for growing bulls in an individually fed intake system, and though significant day-to-day variation exists, the BRANDS program appears to more accurately predict DMI than ADG

Effects of Supplementing Corn Silage to Fall-Calving Heifers and Cows Grazing Tall Fescue on Cow Performance

The objective was to test the effect of fescue cultivars and supplemental feeding of cows grazing fescue pastures on cow performance and pasture management. Primiparous and multiparous Angus-based crossed cows (n = 45) averaging 151 ± 7 d of gestation at turnout, were randomly allocated and stratified to pasture treatment by parity. Each pasture contained 3 cows of different ages, consisting of a young (first-calf heifer), middle-aged (3-5 yrs.), and old (≥ 6 yrs.) cow. Treatment was a 2 by 2 factorial design with two types of pasture (toxin producing or non-toxin producing fescue) and two levels of supplemental feeding (non-supplemented or supplemented at 1% of body weight on a DM basis of corn silage). Toxic fescue pastures consisted of K-31 endophyte infected tall fescue (n = 8) tested at 507 ppm ± 0.82 SEM for ergot alkaloids with a 92.5% infection rate. Non-toxic pastures consisted of novel (MaxQ) and endophyte free varieties (n = 7). Cows were fed silage (32-42% DM and 7.83% CP) daily in fence-line bunks, with feeding amount being adjusted at each weigh date. Cows were weighed on 2 consecutive days prior to turnout (middle of the second trimester), midpoint (beginning of the third trimester), and at about 2 weeks prior to the estimated calving date for herd. Body weight, body condition score, hair score, and rump fat measurements were taken at each weigh date. Supplementation tended (P = 0.07) to increase body weight gain and rump fat (P = 0.06) regardless of fescue type. Cattle grazing toxic fescue tended to have longer hair (P = 0.09) and did not “slick” off as quickly as those that were supplemented (P = 0.08). Cattle grazing toxic fescue exhibited classic fescue toxicosis symptoms, and supplementation improved cow performance regardless of fescue cultivar

Effects of Supplementing Corn Silage to Fall-Calving Heifers and Cows Grazing Bermudagrass and Calf Performance and Physiology

The objective was to test the effect of supplemental feeding on cows grazing bermudagrass pastures on cow-calf performance and pasture management. In a completely randomized design, (n = 24) primiparous and multiparous Angus-based cross cows were allocated to bermudagrass pasture with one of two levels of supplemental feeding (non-supplemented or supplemented at 1% of BW on a DM basis of corn silage). Each treatment consisted of (n = 4) pastures stocked with three cows of different ages, a young (first-calf heifer), middle-aged (3-5 yrs.), and old (≥ 6 yrs.) cow, each averaging 155 ± 14 d of gestation at turnout. Cows were fed silage (32-42% DM and 7.83% CP) daily in fence-line bunks, with feeding amount being adjusted at each weigh date. Cows were weighed on 2 consecutive days prior to turnout (middle of the second trimester), midpoint (beginning of the third trimester), and at about 2 weeks prior to the estimated calving date for the herd. Body weight, body condition score, hair score, hair length, and rump fat measurements were taken at each weigh date. Following the final measurement day, cows were relocated to calving pastures consisting of a mixture of bermudagrass, tall fescue, and prairie grass. Supplemental feeding of late gestation fall-calving cows on bermudagrass pasture did not have an effect on cow-calf performance, calf birth weights, and milk output. However, supplemental feeding of cows with corn silage during the summer resulted in 31% more available forage in the pastures. Overall, there were minimal differences in cow performance while grazing bermudagrass pastures during the summer and with supplemental feeding of corn silage. The greatest advantage comes from a greater amount of forage available, which may offset periods of drought or allow producers to increase stocking rates on their property

Exposure of prepubertal beef bulls to cycling females affects neither age at puberty nor ability to pass an initial breeding soundness examination

Age at puberty is a crucial factor influencing a young bull’s ability to pass a breeding soundness examination (BSE) at a year of age, and reducing that age may prove beneficial to beef producers. For beef females, exposure to mature bulls is known to hasten the onset of puberty and also can reduce the duration of postpartum anestrus. Relatively little research has evaluated the effects of female exposure on beef bull sexual development. Bulls are thought to use visualization rather than olfaction as their primary and preferred way to detect estrus in females. The purpose of this study was to determine whether continuous, long-term fence-line exposure of prepubertal beef bulls to estrouscycling beef females influences a bull’s age at puberty and subsequent ability to pass a BSE

MGA and growth promotants administered to beef feedlot heifers have no effect on subsequent oocyte quality or in vitro embryo production

Beef feedlot heifers have the potential to serve as viable donors of oocytes post-slaughter for in vitro embryo production. Oocyte quality is a critical factor affecting the success of in vitro embryo production and can be influenced by factors such as age and reproductive status, ovarian follicle size, and nutritional status of the donor female. In a conventional feedlot setting, heifers are typically administered steroid-based growth promotants and fed melengestrol acetate (MGA) for suppression of estrus, which increases circulating concentrations of reproductive steroids, particularly estradiol. The effects of these management practices on oocyte quality and numbers are unknown. The purpose of this study was to compare oocytes harvested from traditionally managed beef feedlot heifers implanted with growth promotants and fed MGA with oocytes from heifers given neither MGA nor growth promotants, and to evaluate potential effects of these feedlot management practices on early embryo development

Induction of Estrus in Anestrous Suckled Beef Cows

Suckled anestrous beef cows (n=362) received either: 1) an intravaginal implant containing progesterone for 7 days plus a 1 mg injection of estradiol benzoate 24 to 30 hours after implant removal; 2) an intravaginal implant containing progesterone for 7 days; 3) a sham implant for 7 days plus a 1 mg injection of estradiol benzoate 24 to 30 hours after implant removal; or 4) a sham implant for 7 days. Treatment with progesterone resulted in resumption of luteal function in suckled anestrous beef cows with most cows developing corpora lutea with a typical lifespan, whereas treatment with estradiol benzoate enhanced the expression of estrus