PSIV-18 Pro- and anti-inflammatory cytokines in the uterine environment throughout beef heifer development with supplemental protein

Nutrition is a major component in successful heifer development, influencing age at puberty and the uterine environment, therefore, impacting reproductive efficiency. Different diets can influence systemic inflammation, however, the effect on uterine cytokines has not been determined. Our objective was to evaluate the effect of varied levels of dietary protein on inflammatory cytokines in the uterine environment of developing heifers. Commercial Angus heifers (n = 60) were blocked by body weight, then allocated to receive one of three dietary protein supplementation treatments (n = 20 per group, n = 5 per pen): 10% crude protein (CP; 100% corn), 20% CP [75% dried distillers’ grains (DDG) 25% corn], or 40% CP (75% soybean meal 25% DDG). Supplements were provided four times weekly for six months with ad libitum native grass hay, mineral supplement, and water. Body weight, BCS, and blood was taken every 14d. Uterine fluid was collected every 28d to determine presence of cytokines IL1α, IL1β, TNFα, IFNγ, IL10, IL4, and IL6. The GLIMMIX procedure (SAS 9.4) was used with fixed effects of supplementation, month, and their interaction; random effects of block, interaction of block and supplementation, and heifer within the interaction; and repeated measure of month. Concentrations of IL1β, TNFα, IFNγ, and IL10 shifted throughout development (P < 0.0002). Cytokine IFNγ was also affected by month of development (P = 0.002) and tended (P = 0.06) to decrease as CP increased. Presence of each cytokine was then recorded as binary and analyzed by the frequency procedure (SAS 9.4) to determine a uterine cytokine profile. Pro-inflammatory cytokines IL1α, IL1β, and TNFα occurred together more frequently following the beginning of supplementation. In conclusion, inflammatory cytokines shift throughout heifer development, potentially leading to differences in future reproductive success. Further research is needed to determine the dietary influence for optimal uterine environment development.

102 The National Center for Applied Reproduction and Genomics (NCARG) in Beef Cattle: supporting improvements in reproductive management

Limited transfer of existing and emerging reproductive technologies to beef cattle enterprises precludes those enterprises from reaching their economic potential and places them at a competitive disadvantage relative to livestock enterprises where such technologies are being implemented more aggressively. On the other hand, and until now, the beef cattle sector has never had the reproductive tools available to facilitate widespread successful adoption of these technologies within the industry. Hence, the need for increased efforts to transfer technology to the industry has never been greater. The National Center for Applied Reproduction and Genomics (NCARG) in Beef Cattle will serve as a new model for research and technology transfer wherein industry participants at all levels and from across the US are afforded the opportunity to access information and acquire new skills that will improve reproductive management and resulting genetic makeup of our nation’s beef cattle industry. Comprehensive educational training programs will be developed for practicing veterinarians, extension livestock specialists, allied industry, producers, and students that will enable various segments of the beef cattle sector to acquire (through face-to-face and distance-learning applications) new knowledge and skills that will aid in the successful adoption of reproductive procedures/biotechnologies. Curriculum modules designed to support improvements in reproductive management will be comprised of the following: 1) Heifer development programs including reproductive tract scoring, fetal aging and sexing; 2) Breeding management, including estrus synchronization, artificial insemination, sex-sorted semen, and embryo transfer; 3) higher education student internships in reproductive management; and 4) on-farm beef heifer development and marketing programs patterned after the Missouri Show-Me-SelectTM Replacement Heifer Program. In addition, a graduate certificate program will be offered, entitled “Bovine Reproductive Management and Genomic Technologies.” Collectively, NCARG will serve as a new model for research and technology transfer intent on improving reproductive management and genetic makeup of our nation’s beef industry.

157 Impact of weaning strategy on heifer performance and reproductive development

Weaning is recognized as one of the most stressful times of a beef calf’s post-natal life. The objective of this study was to determine if weaning strategy impacts heifer development and reproduction. At 7 months of age, 96 predominantly Angus heifers at 2 locations were assigned to 1 of 3 weaning treatments: abrupt relocation of the calf on d0 (Abrupt, n = 32), fenceline contact starting on d0 prior to relocation of the calf on d7 (Fence, n = 33), and abrupt relocation of the calf on d84 (Late, n = 31). Calf weights, hip heights, and body condition scores (BCS) were collected to evaluate post-weaning performance. Reproductive tract scores (RTS; 0–5 scale, 5=most mature) were assigned every 54 days from d56 to d218. Heifers were synchronized using a 7-day CO-Synch + CIDR® protocol and artificially inseminated (AI) on d246. Data were analyzed using PROC MIXED of SAS with repeated measures. Statistical significance was determined at P ≤ 0.05. Late heifers were heavier at d28 and d56 than Abrupt and Fence (P < 0.05), but BW was similar across treatments starting at d84. Average daily gain (ADG) was greater for Late than Abrupt (0.39 and -0.03 kg/day respectively; P < 0.01) and tended to be greater than Fence (0.16 kg/day; P = 0.07) to d28; however, Late had lower ADG than Abrupt and Fence from d28-84 (0.66, 0.83, and 0.81 kg/day respectively; P < 0.05). No treatment differences were observed in BCS or hip height. Late tended to have greater RTS than Abrupt and Fence (2.54, 2.20, and 2.16 respectively; P ≤ 0.10) on d56, but there was no difference on or after d164. Fence tended to have greater AI conception rates than Abrupt and Late (66%, 44%, and 42% respectively; P ≤ 0.08). This data indicates there were initial performance differences based on weaning strategy, but this had minimal impact on heifer development.

375 The effect of supplemental protein from weaning until first breeding on heifer development and uterine environment characteristics

Replacement heifer development is one of the most critical components of productive beef operations. By identifying the ideal uterine environment in pre-breeding heifers, fertility and reproductive efficiency can be maximized. Our hypothesis was that different levels of protein supplementation would affect the rate of development and uterine environment of beef heifers. To test the effects of dietary supplementation on these outcomes, a randomized complete block design with repeated measures was implemented. Commercial Angus heifers (n = 60) were blocked by BW into 4 weight classes. Within each weight class, three pens of 5 heifers each were randomly assigned to one of three treatment groups of supplemental protein [10% (control), 20% (P20), and 40% (P40)]. All heifers were allowed access to ad libitum grass hay. Bodyweight and BCS were collected every 2 weeks to monitor heifer development. Uterine fluid samples were collected monthly by flushing with sterile saline to evaluate components of the uterine environment. Relative uterine pH was calculated by subtracting saline pH from the uterine flush pH. Separate mixed model ANOVAs and mean separation via PROC GLIMMIX (SAS 9.4, Cary, NC) were used to determine if protein supplementation treatments, time and their interactions influenced BW, BCS, or uterine environment. Bodyweight of the control group was significantly lower (P < 0.05) than P20 or P40 groups from December to March. There was an interaction between treatment and time for relative uterine pH (P = 0.002). In November, the P40 group exhibited less change in pH compared to the control group (0.33±0.1 vs. 0.74±0.1; P < 0.05). Whereas in December the P40 (0.23±0.1) group showed more basic uterine environment compared to the P20 (-0.22±0.1) or control (-0.13±0.1) groups (P < 0.05). In conclusion, higher protein supplementation does improve heifer growth and development, as well as altering the pH of the uterine fluid from weaning to first breeding