The development of replacement heifers is crucial for breeding success and herd efficiency. Nutritional management can affect not only reproductive development, but also the inflammatory status of the uterine environment, which may impact reproductive functions such as pregnancy establishment and development. The study herein evaluated the concentration of cytokines and chemokines in the uterus of heifers supplemented with different levels of protein. Angus heifers (n = 60) were blocked by body weight and randomly assigned to one of three treatments based on protein supplementation level: control of 10% crude protein (CON), 20% crude protein (P20), or 40% crude protein (P40). Body weight, body condition score, and blood samples were taken every two weeks for 140 days to monitor development. Uterine flushes were performed monthly and concentrations of cytokines (IL-1α, IL-1β, TNF-α, IFN-γ, IL-10, VEGF-α, IL-17A, and IL-36RA) and chemokines (IL-8, MCP-1, MIP-1α, and MIP-1β) were quantified via ELISA multiplex. To test if there were mean differences in cytokines between the treatment groups or over time, PROC GLIMMIX (SAS v 9.4) was utilized. Concentrations of all cytokines and chemokines, except IL-1α, changed throughout heifer development (P < 0.05). Heifers in the P40 treatment group displayed reduced concentrations of MCP-1 (P = 0.007) and tended to have decreased concentrations of IFN-γ (P = 0.06). Cytokine IL-36RA tended (P = 0.06) to be affected by protein level, with the lowest concentrations observed in CON heifers. Most cytokines and chemokines increased following the initial month of supplementation (P < 0.05). The increase in concentrations after one month may indicate an adaptive response in the uterus to diet change. Cytokines and chemokines fluctuated due to physiological changes occurring during development. Further research is needed to determine the influence of nutrition on uterine inflammation and long-term impacts on reproductive function.

Bulls often experience various levels of nutrient availability throughout the year. Nutritional management is a critical factor on overall ejaculate composition and the ability to get females pregnant. We hypothesized that differing nutritional levels and body condition score (BCS) affects reproductive fertility parameters in bulls. Mature Angus bulls (n = 11) were individually housed and randomly assigned to one of two dietary regimens: 1) over-fed (n = 5) or 2) restricted (n = 6). Bulls were fed the same ration at different volumes to achieve desired effects resulting in 8 individual treatments: gain to an over-fed body condition score ([BCS]; GO), gain after nutrient restriction (GR), loss after an over-fed BCS (LO), loss from nutrient restriction (LR), maintenance at ideal adiposity (BCS = 6) after overfeeding (IMO), maintenance at ideal adiposity after nutrient restriction (IMR), maintenance at an over-fed BCS (BCS = 8; MO), and maintenance at a restricted BCS (BCS = 4; MR). Body weight (BW) and BCS were recorded every two weeks to monitor bull weight and BCS changes. Scrotal circumference was measured every 28 d. Body fat and sperm motility and morphology were evaluated every 84 d. Scrotal circumference, motility, and morphology were normalized to the initial value of each bull. Thus, allowing the individual bull to serve as a control. Statistical analyses were conducted with PROC GLIMMIX of SAS as a complete randomized design to determine if treatment influenced BW, BCS, scrotal circumference, motility, morphology, and adipose thickness. Scrotal circumference (P < 0.001) had the least amount of deviation from initial during the LR (0.29 ± 0.44) treatment and the greatest during the MO (3.06 ± 0.44), LO (2.28 ± 0.44), MR (2.43 ± 0.44), GR (3.03 ± 0.44) and IMR (2.91 ± 0.44) treatments. Sperm motility was not affected by nutritional treatments (P = 0.55). Both head and total defects of sperm differed (P = 0.02) due to nutritional treatments. Increased head abnormalities occurred during the LO (37.60 ± 8.61) treatment, with no differences between the other treatments. Total defects increased during the LO (43.80 ± 9.55) treatment with similar increases in bulls during the GR (29.40 ± 9.55) and IMR (35.60 ± 9.55) treatments. In conclusion, male fertility was impacted when a deviation from a BCS of 6 occurred which could be detrimental to reproductive and beef production efficiency.

IntroductionHigh quality semen is essential for reproductive efficiency. Nutrition and environmental factors impact the ejaculate components, like cytokines, that are essential for pregnancy establishment. We hypothesized that differing nutritional periods and body condition scores would affect seminal plasma cytokine concentrations of bulls.MethodsMature Angus bulls (n=11) were individually housed and randomly assigned to either over-fed (n=5) or restricted (n=6) treatment pathways. Bulls were fed different volumes of a single ration creating 8 individual treatment periods. Body weight and body condition scores were taken every 14 d to manage intake volumes. Ejaculates were collected every 84 d to determine seminal plasma cytokine profiles. A complete randomized design was used to evaluate seminal plasma cytokines after each nutritional treatment. Initial cytokine concentrations and volume of the ejaculate were included as covariates.ResultsAll cytokines returned to initial concentrations following maintenance treatments at an ideal body condition score of 6. Nutritional treatments affected (P ≤ 0.05) IFN-γ, IL-8, MIP-1α, MIP-1β, TNF-α, IL-1β, and VEGF-A. However, TNF-α, IFN-γ, and MIP-1α had the greatest impact on cytokine profile.DiscussionNutritional levels and adiposity altered seminal plasma cytokine concentrations which could potentially impact the inflammatory balance of the uterus and the immune responses necessary for pregnancy establishment.

Dietary cation-anion modification in cattle has effects on productivity through various means. Alterations of dietary cation-anion balances has been shown to affect plasma osmolarity. Plasma osmolarity is directly related to renal function and metabolism in all animals. In a feeding operation with a single diet fed to a similar population of animals, plasma osmolarity should fall within a somewhat normal range (approximately 270-310 mOsm). However, subtle, yet very distinguishable differences will exist between animals. In theory, variances in osmolarity may reflect differences in metabolism and as such, efficiency of feed utilization. Many researchers believe that utilizing residual feed intake (RFI) expressed in a population as a selection tool will lead to improved production efficiency in beef cattle. Residual feed intake is normally distributed. Like osmolarity, RFI will have subtle, yet very distinguishable differences existing between animals. The objective of this study is to determine if there are any detectable relationships between plasma osmolarity measurements and RFI within a controlled test population and to further determine how this information may be used in improving the utility of RFI measurements. In this study (77d), intake, BW, and ultrasound measurements of yearling heifers were observed. Frozen (-60 o C) plasma samples were thawed at room temperature and osmolarity determined. Plasma samples (n=67, n=70) were analyzed to determine osmolarity. All data were analyzed using the CORR procedures of SAS. Plasma osmolarity measured on day 70 demonstrated a weak relationship to RFI (r = 0.226; P = 0.0); no other correlations existed (P > 0.10) in this data set. There were little to no relationships between osmolarity and ultrasound rump fat (P > 0.90), rib fat (P > 0.98) and intramuscular fat ((P > 0.13). Only days 21 and 35 had relationships between ribeye area and osmolarity. (P = 0.04; P = 0.0002). There were also minimal detectable relationships of osmolarity with metabolic body size (P > 0.06) or intake (P > 0.08). However, osmolarity values fluctuated over the nine (year 1) or ten (year 2) different time points, thus plasma osmolarity measurements taken during or shortly after dietary adaptation may not directly correlate to an animal's RFI value. However, analysis of how animals establish a cation-anion balance may have some relationship to the animals RFI phenotype. First and foremost, to my four legged friends you are forever my inspiration. I'd like to thank my tandem of advisors, Dr. Bowdridge and Dr. Felton, for their patience and willingness throughout my graduate career. I would not be here today if it weren't for Dr. Bowdridge. He brought me here to coach the livestock judging team, which has proved to be a challenging, but very rewarding endeavor. Although, not my major advisor, he has always been there to help any way he can, whether it be with my team or with research. Dr. Felton, thank you for your patience when I am gone on the road and for always being in my corner. Without y...

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