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Recent Submissions
Changes in photoperiod during the dry period impact colostrum production in Holstein and Jersey cows
Alward, Kayla J.; Duncan, A. J.; Ealy, Alan D.; Dahl, Geoffrey E.; Petersson-Wolfe, Christina S.; Cockrum, Rebecca R. (Elsevier, 2025-02)
Multiparous Holstein cows exposed to short-day photoperiod (SDPP) of 8 h of light per day during their dry period produced up to 3.2 kg more milk per day compared with cows exposed to long-day photoperiod (LDPP) of 16 h of light per day; it is unknown if a similar response would be observed for Jersey cow milk production. The objective of this study was to determine the effect of photoperiod during the dry period on subsequent colostrum and milk production in Holstein and Jersey cattle. Holstein and Jersey cows (n = 33) were dried off 60 d before their due date and randomly assigned to SDPP (Holstein, n = 9; Jersey, n = 8) or LDPP (Holstein, n = 8; Jersey, n = 8) until calving. Cows were weighed at the time of enrollment (d 0) and were housed in an enclosed barn at 20°C and exposed to 250 to 450 lx during periods of light and <10 lx during periods of darkness. At calving, colostrum volume was weighed and tested for relative protein concentration with a Brix refractometer and a sample was collected for component analysis (fat, protein, lactose, SNF) via infrared spectroscopy, as well as IgA, IgG, IgG1, IgM, lactoferrin, and SCS analysis. After calving, cows were returned to the freestall barn and exposed to ambient photoperiod and temperature. Milk production data were collected for 15 wk postcalving. Data were analyzed using PROC MIXED in SAS (SAS 9.4; SAS Institute Inc., Cary, NC) with treatment, breed, and d 0 weight as fixed effects. PROC MIXED with repeated measures was used to evaluate the relationship of day length and breed with mature milk volume, fat, and protein production. Random effects included replicate, lactation number, genetic inbreeding percentage, previous lactation mature equivalent 305-d protein production, and calf sex. For colostrum, Brix score, colostral protein, fat, IgA, and IgM were increased in Jersey cows compared with Holstein cows. Total colostrum weight, SNF, lactose, lactoferrin, IgG, IgG1, and SCS did not differ by breed or treatment. Postcalving, ECM production was increased in Holstein cows compared with Jersey cows but unaffected by photoperiod treatment. Conversely, milk protein percentage was increased for Jersey cows relative to Holstein cows but was unaffected by photoperiod treatment. Milk fat increased in LDPP Holstein cows compared with SDPP Jersey cows during the first week of lactation, which is likely due to the transition from colostrum to mature milk production. Overall, photoperiod did not affect colostrum production, but differences by breed were detected. Photoperiod during the dry period did not affect mature milk production or protein, but milk fat percentage was affected by photoperiod × breed. Therefore, altered lighting during the dry period does not unfavorably affect colostrum or milk production in Jersey or Holstein cows.
Cumulus cell expansion, nuclear maturation and embryonic development of bovine cumulus-oocyte complexes matured in varying concentrations of follicular fluid
Negron-Perez, Veronica M.; Al Naib, Abdullah; Zezeski, Abigail L.; McCracken-Harlow, Victoria L.; Perry, George A.; Ealy, Alan D.; Rhoads, Michelle L. (Public Library of Science, 2025-02-07)
In this study, we tested the overall hypothesis that CC expansion and early embryo development would be improved by including follicular fluid (FF) from small or large follicles in the oocyte maturation medium. In the first experiment, FF aspirated from bovine abattoir ovaries was added to the maturation medium at 0, 25, 50, 75 or 100%. Images of individual COCs were captured at 0, 6, 12 and 19 hours (h) of the maturation period and analyzed to calculate change in the total area over time. Cumulus cell expansion was greatest in COCs matured in 75% and 50% FF, and these differences were detectable at 12 (75% FF only) and 19 h (50% and 75% FF) of maturation. The improvement in CC expansion was greatest when FF from small follicles was used. Treatments for the subsequent experiments were selected based upon the results of the first experiment. Oocyte nuclear maturation rates were observed after supplementing the maturation medium with 0 or 75% FF and maturing for 19 h. The rate of nuclear maturation as determined by the presence or absence of the first polar body was similar between control (0% FF) and treated (75% FF) groups. In the final experiment, COCs were matured in 0%, 50% or 75% FF in preparation for IVF. Duration of the maturation period (12, 19 or 22 h) and size of the follicles from which FF was collected (small or large) also varied. In general, FF supplementation at 50% did not affect the zygotes’ developmental potential (neither increased nor decreased). Supplementation of maturation medium with 75% FF from small follicles consistently reduced measures of embryo development while 75% FF from large follicles yielded mixed results. It is concluded that FF supplementation improves CC expansion, but the greater CC expansion does not benefit subsequent embryo development. Notably, however, the 50% FF treatment did not reduce blastocyst rates, indicating that FF can be included in maturation media at concentrations of 50% or less with no detriment to IVF outcomes.
Maturation of bovine cumulus oocyte complexes in follicular fluid with or without estradiol, progesterone or the combination affects cumulus cell expansion and blastocyst development
Harl, Audra W.; Negron-Perez, Veronica M.; Stewart, Jacob W.; Perry, George A.; Ealy, Alan D.; Rhoads, Michelle L. (Public Library of Science, 2025-06)
Although laboratory procedures for in vitro bovine embryo production have improved immensely, developmental capacity following fertilization is still limited, especially in comparison to in vivo-produced embryos. In vivo, the maturing oocyte is enclosed in the ovarian follicle and surrounded by its cumulus cells and follicular fluid. Hormones and other components of the follicular fluid change dynamically as the follicle develops and approaches ovulation. The importance of the in vivo follicular microenvironment for oocyte developmental competence has not been well defined, however. Therefore, the objective of this study was to investigate the impact of follicle size and relative estradiol and progesterone concentrations on cumulus cell expansion and early embryo development following follicular fluid exposure during maturation in vitro. All experiments and replicates contained a standard formulation control maturation medium (cOMM). Follicular fluid was collected via needle aspiration from small (2–5 mm diameter) and large (10–20 mm diameter) follicles and pooled according to size. The follicular fluid was added to a hormone-free base medium (eOMM) as follows: supplemented with 75% untreated large follicular fluid (LFF75), 75% untreated small follicular fluid (SFF75), 75% charcoal-stripped large follicular fluid (csLFF75), 75% charcoal-stripped small follicular fluid (csSFF75). Progesterone and/or estradiol were added to the charcoal-stripped follicular fluid treatments based on average concentrations found in fluid from pooled large or pooled small follicles. These six treatment media were formulated using eOMM as a base with the following designations and additions: 75% charcoal-stripped large follicular fluid + 37 ng/ml estradiol (csLFF+E2), 75% charcoal-stripped small follicular fluid + 23 ng/ml estradiol (csSFF+E2), 75% charcoal-stripped large follicular fluid + 160 ng/ml progesterone (csLFF+P4), 75% charcoal-stripped small follicular fluid + 140 ng/ml progesterone (csSFF+P4), 75% charcoal-stripped large follicular fluid + 37 ng/ml estradiol + 160 ng/ml progesterone (csLFF+E2+P4), or 75% charcoal-stripped small follicular fluid + 23 ng/ml estradiol + 140 ng/ml progesterone (csSFF+E2+P4). Cumulus expansion in the csSFF75 maturation medium was less than that of its untreated counterpart (SFF75), while cumulus cell expansion was similar for LFF75 and csLFF75. The addition of estradiol to the follicular fluid treatments was beneficial and improved cumulus cell expansion to values similar to cOMM, while progesterone alone had no effect. The greatest cumulus cell expansion was observed when both estradiol and progesterone were added to the follicular fluid treatments. Cleavage rates were generally reduced by follicular fluid treatments, with the exception being csSFF+P4 which had a cleavage rate similar to oocytes matured in cOMM. Blastocyst rates for LFF75 and csLFF75 were similar to cOMM, while SFF75 and csSFF75 reduced blastocyst rates. Interestingly, the follicular fluid treatments with added progesterone either maintained or improved blastocyst rates such that csLFF+P4 and csSFF+P4 were similar to cOMM. The same could not be said for any of the treatments containing estradiol, whether alone or in combination with progesterone. Taken together, these results suggest a dichotomous relationship between estradiol and progesterone during maturation. Estradiol supports cumulus cell expansion while progesterone concentrations during oocyte maturation are more important for subsequent embryo development.
Roundtable: Establishing Veterans Studies as an Academic Discipline
Grohowski, Mariana; Dubinsky, James M.; Avilés-Santiago, Manuel G.; Bradford, Anita Casavantes; Craig, Jim; Hart, D. Alexis; Hinton, Corrine; Hodges, Eric; Maurer, Bill; Pencek, Bruce; Wright, Wanda (Virginia Tech Publishing, 2025-08-28)
Ten individuals who played key roles in formalizing veterans studies at American universities or within professional associations reflect on the field’s origins, key developments, institutional support, social and historical influences, and its evolution over time. Their responses, condensed and edited for clarity, elucidate the invisible, arduous, and complex labor involved in attempting to establish an academic discipline in 21st century America.
Effect of maturity at harvest of small grain grasses on the nutritional composition of forage and ration formulation
Ferreira, Gonzalo; Teets, C. L.; Galyon, Hailey; Cappellina, Anna; Schultz, Milton; Payne, Kathryn; Stewart, Shamar; Thomason, Wade E. (2025-02-09)
We hypothesized that, relative to harvesting small-grain grasses at the soft dough stage (SFT) of maturity, harvesting small-grain grasses at the boot stage (BT) of maturity would result in less expensive dairy rations when commodity prices are high but not when commodity prices are low. Small plots of small-grain grasses were planted during the fall of 2020 and 2021 in Blacksburg, Blackstone, and Orange, Virginia. In each year and location, 2 varieties of barley, 2 varieties of rye, and 4 varieties of triticale were planted in plots replicated 6 times, yielding 288 plots. Within each year and location, we harvested half of the plots at BT and the other half at SFT. For each of the 6 small-grain grasses, we formulated 8 rations according to 8 different scenarios using the least-cost optimizer. The scenarios included high and low commodity prices, high and low dietary forage (60% and 40% forage, respectively), and the inclusion of small-grain grasses harvested at BT or SFT. Harvesting at SFT yielded 107% to 205% more DM than harvesting at BT. Relative to BT, small-grain grasses harvested at SFT had greater concentrations of OM, NDF, ADF, ADL, and starch but lower concentrations of CP. Relative to BT, small-grain grasses harvested at SFT also had a greater concentration of undegraded NDF (NDF basis). Species had minimal influence on the nutritional quality of small-grain grasses for silage. Under a low-price scenario, the ration formulation system ignored all 6 small-grain grass silages and included corn silage as the only forage source when we did not limit its inclusion. Under a high-price scenario, the ration formulation system included all 6 small-grain grass silages when formulating low-forage diets with unlimited corn silage. However, a preference between BT and SFT stages did not exist, with the optimizer not consistently selecting a specific maturity stage. After evaluating the yields, the chemical composition, and the effects on ration formulation in this study, future studies should aim to evaluate the influence of maturity at harvest of small-grain grasses on cow performance and environmental impacts.