bluuebunny/crossref_metadata_2025 huggingface dataset:
188 Extension Programming in Forages: Opportunities and Challenges
Authors: Dillard Sandra L
Published: October 2021

Even though forage and grazing lands represent the largest land use in the United States, the number of forage faculty positions nationwide has decreased by 47% in the last 15 years, with only an estimated 2.3 forage research and Extension full-time equivalents (FTE) per state. This challenge has made partnerships with county/regional agents and Extension faculty from other states an increasingly important component of a successful Extension program. Whereas virtual/online programs existed prior to 2020, people of all ages are currently more comfortable and adept with virtual technology because of the COVID-19 pandemic. Moving forward, virtual meetings and hybrid meetings will likely become more routine, making it possible to disseminate knowledge to producers locally and across the state, region, and country concurrently. This approach will enable Extension educators to be more efficient in their knowledge transfer as illustrated by programs such as the Bermudagrass Hay Summit which has seen an almost six-fold increase in attendance from 2020 to 2021 because travel is not required. Lastly, there is a largely untapped opportunity in on-farm demonstrations and research. An example of how this can positively affect adoption of new technology is the regional program Alfalfa in the South. This program combines both on-farm and experiment station research. As a result of on-farm demonstrations, producer interest in adoption of alfalfa across Alabama and Georgia has increased in the last 3 years. There are many challenges to Extension programming in forages, but there are also ample opportunities to partner with other state Extension programs, as well as with producers to disseminate forage and pasture management effectively and efficiently to the forage and livestock sectors across the United States.
194 Avian Breast Muscle Development and Growth: Influence of Temperature on Growth Mediated by Breast Muscle Adult Myoblasts (Satellite Cells)
Authors: Velleman Sandra G
Published: October 2021

Newly hatched poults and chicks have immature thermoregulatory systems and are not able to maintain a constant body temperature when exposed to hot or cold ambient temperatures. During the immediate posthatch period during handling and transport, poults and chicks are commonly exposed to acute thermal conditions. This immediate posthatch period is when satellite cells, adult myoblasts, have their highest period of mitotic activity and are sensitive to extrinsic stimuli including ambient temperature. Variable temperatures can have long-lasting positive or negative effects on skeletal muscle growth. Satellite cells are a self-renewing multipotential stem cell population located between the basement membrane and sarcolemma of muscle fibers. They are responsible for all posthatch growth of muscle through muscle fiber hypertrophy. Results have shown that satellite cells are more sensitive to thermal stress during the period of satellite cell proliferation than during differentiation into multinucleated myotubes, and that pectoralis major muscle satellite cells from growth-selected lines of chickens and turkeys are more sensitive to temperature. Recent findings have shown that the rapamycin, mTOR, signaling pathway which is involved in muscle growth through hypertrophy is differentially affected by thermal stress in a growth-dependent manner. Since satellite cells are a stem cell population, they can also transdifferentiate into other cellular lineages. Anaerobic muscles like the pectoralis major muscle are more prone to converting to an adipogenic lineage compared to aerobic muscles like the biceps femoris. Thus, variable temperatures can impact the intramuscular fat content of the breast muscle. Taken together, changes in ambient temperature alter satellite cell function causing long-term effects on growth, morphological organization, and composition of the pectoralis major, breast, muscle.
199 Do the Microbiomes of Horses Process Nutrients Differently Based on Keeper Status?
Authors: Johnson Alexa C , Biddle Amy S
Published: October 2021

This study reports the differential response of the equine gut microbiome to protein and/or carbohydrate based on keeper status (easy keeper (EK), medium keeper (MK), hard keeper (HK)). Anaerobic equine fecal samples (n = 12 total, n = 3 / EK, MK, HK of four breeds) inoculated microcosms with three dietary conditions (C = Carb (cornmeal), P = Protein (soybean meal), and M = mix (50% C, 50% P)). Over 48 hours, fermentation products were measured using colorimetric assays and high-performance liquid chromatography. Microbial populations were surveyed using 16S rRNA gene sequencing analyzed by QIIME2. Linear mixed models were fit with fixed effects of Treatment and Keeper status and their interactions, with random effects of HorseID. Differences in fermentation products by keeper status included: MK had higher pH and greater gas production, EK produced higher hydrogen sulfide, and HK had greater total protein. Total SCFA was not different between keeper status (P = 0.89) but the acetate: propionate ratio was highest for HK (2.45mM) and lowest for EK (1.85mM) (P = 0.05). Isobutyrate production was highest in HK (2.34mM) compared to MK (0.85mM) and EK (0.17mM). Treatment had significant effects across all measurements; M and C treatment values were similar reflecting microbial preferences for carbohydrates before protein. P treated trials had increased fermentation outputs due to lower acidity effects. Keeper status had no effect on α-diversity (P > 0.05) however HK horses were least affected by treatments. P treated samples were more diverse than C and M (P < 0.001). Spearman correlation of Keeper x Treatment identified Oligosphaeria spp. in EK (r = 0.49) and Fusobacteria spp. in HK whole fecal samples (r = 0.37). These data suggest that while the compositions of the gut microbiomes of keeper groups were similar, they were functionally different in processing key nutrients.
202 Nature versus the NRC: Utilizing an Understanding of the “natural” Diet of the Horse in Contrast to Defined Guidelines
Authors: Gordon Mary Beth
Published: October 2021

A comprehensive look at nutrients available in nature compared to equine nutrient requirements and the modern diets we feed them. Horses can survive on a variety of feedstuffs that they ingest if they are relatively equine-specific and the horses’ forage requirements are met for basic gastrointestinal health. It is safe to say that some horses in the United States continue to be fed as “nature-intended” with 24/7 access to fresh pasture or adequate plant material and enough room to continually move and graze. Many other horses, however, have only limited or no access to pasture and their movement is greatly restricted via stall confinement or small areas to move. In addition, there is a wide variety in what we ask horses to do, from horses that are simply pasture pets, to horses performing as elite-level athletes in racing and competitions. And when we look at all these factors from a nutrition perspective, how do the nutrients provided by nature match up with the requirements as set by the National Research Council’s Nutrient Requirements for Horses? And how do these nutrients provided by nature compare to how we are feeding many modern horses today? This presentation will examine these factors and shed light on differences between the NRC nutrient requirements and what is provided by both nature and/or modern feeding practices in several scenarios, to identify areas of mismatch that could be potentially addressed or researched further in an effort to improve the health and well-being of horses.
206 Beyond NRC Requirements: The Role of Non-nutritives in Equine Health and Performance
Authors: Warren Lori K
Published: October 2021

Billions of dollars are spent annually on dietary supplements, with similarities between products consumed by humans and those offered to horses and other animals. Dietary supplements encompass a variety of substances, some non-nutritive and others recognized as essential nutrients, but all are fed with the intent of providing a health or performance benefit beyond that supported by the normal diet. Though many of these products are sold without sufficient evidence of efficacy, their increasing popularity has driven horse owner curiosity and researcher interest. Over the past two decades, funding for research on dietary supplements in horses has exceeded that spent addressing knowledge gaps in the nutrient requirements of horses. Many of these substances are difficult to study (e.g., herbs, botanical extracts), due to their complex composition, unidentifiable active compounds, or broad biological effects that are difficult to characterize. Others have shown promise for reducing inflammation and improving immunocompetence, including various fatty acids, probiotics, prebiotic fibers, and antioxidants. Among these are well-known nutrients that are either being fed above current requirements (e.g., vitamins, minerals), or are presumed to be essential but requirements have not been established for the horse (e.g., essential fatty acids, amino acids, vitamins). In most cases, the benefits are not realized in an already healthy horse but are instead demonstrable in animals under high stress conditions (e.g., intense exercise, transport) or states of immunocompromise (e.g., inflammatory disease, senior horses, foals). Should dietary supplements be included in discussions of nutrient requirements and a future revision of the horse NRC publication? When does a compound become a nutrient – or a drug? Could there be a situational requirement for a dietary supplement if it returns the animal to homeostasis when the regular diet does not? This presentation will provide fodder for a group discussion on future directions of equine nutrition.
219 Effects of Feeding Low Protein Diets with Additional Supplementation of First Five Limiting AA on Performance and Diarrhea Incidence in Weaned Pigs
Authors: Van Niekerk Natasha , Htoo John K , Vega Caroline Gonzalez
Published: October 2021

An experiment was conducted to evaluate the effect of feeding low crude protein (CP) diets and supplying 110% of the first 5 limiting AA on performance and diarrhea incidence in weaned pigs. One of 3 treatments were randomly assigned to 81 piglets (BW: 8.2 ± 1.2 kg; 9 pens/treatment; 3 pigs/pen) during 2 phases (3 wk each): a high CP (HP; 21 and 18%), a low CP (LP; 18 and 15%), or a low CP at 110% Lys, Met, Trp, Thr, Val requirements (LPAA; 18 and 15%) diet for phase 1 and 2, respectively. Pigs had ad libitum access to feed and water. Data were analyzed using PROC MIXED of SAS. During phase 1, pigs fed HP had the greatest ADG (P < 0.05), but ADFI and G:F were not different among treatments. In phase 2, no effect of treatments was observed on growth performance. Overall, pigs fed LPAA had the lowest (P < 0.05) ADG and G:F, and feeding LP decreased (P < 0.05) G:F. The ADFI was not affected by the treatments. Only during wk 3, pigs fed LPAA increased (P < 0.05) and LP tended to increase (P < 0.10) frequency of diarrhea compared to HP. On d 21, no treatment effect was observed for ileal villi height, but LPAA reduced (P < 0.05) and LP tended to reduce (P < 0.10) crypt depth compared to HP. Diet analysis revealed that LP was deficient in Ile and non-essential AA (NEAA), and LPAA contained inadequate levels of Ile, Leu, His and NEAA, which explains why reduced pig performance was achieved with these 2 diets. In conclusion, low CP diets, even with additional supplementation of the first 5 limiting AA, if deficient in the next limiting AA, results in negative effects on performance and diarrhea incidence.
220 Effects of Actisaf HR+ SC47 Live Yeast Probiotic Fed at Two Levels to Sows on Offspring Performance Before and After Weaning
Authors: Loughmiller Joe , Corley Jimmie , Gourley Gene , Hotze Brian , Bruder Emily , Catunda Fabio
Published: October 2021

750 sows (PIC line 42) were used to evaluate the effects of ActiSaf HR+ SC47 live yeast probiotic (AS) on sow and litter performance when fed to sows and their weaned piglets (PIC line 42 x 359). 250 multiparous sows per treatment (average parity 3.6) were fed the control diet without a live yeast probiotic (NC) or a diet with 250 mg/kg AS from breeding through lactation (LY1) or 250 mg/kg AS during gestation and 500 mg/kg AS during lactation. Weaned pigs from these sows were subsequently fed 4-phase nursery diets containing 0 (wNC) or 1 g/kg AS from d 0–10 after weaning followed by 500 mg/kg AS (wLY) from d 10–42 after weaning. This provided a 3x2 nursery trial design. During lactation, number of pigs born; born live varied by treatment (P < 0.05). After weaning, wLY fed pigs had lower BW on d 12, 23; d 0–12 ADG, ADFI, lower d 0–42 ADFI and $/kg gained (P < 0.05). Pigs fed wLY after weaning also tended towards lower d 42 BW and d 0–42 ADG (P < 0.06; Table 1). Conversely, weaned pigs from sows fed LY1 or LY2 had higher ADG and ADFI from d 0–12 and d 0–42 after weaning (P < 0.05) versus pigs from sows fed NC. Pigs from sows fed LY1 or LY2 also had higher BW at d 12, 23, and 42 after weaning than pigs from sows fed NC. Pigs from sows fed LY1 and LY2 tended to have lower nursery $/kg gain (P < 0.06) than pigs from sows fed NC. No significant interactions were observed. Feeding ActiSaf HR+ SC47 live yeast probiotic to gestating and lactating sows improved their weaned pigs’ growth performance and tended to improve piglet cost of production after weaning.
222 Corn-expressed Phytase Modulates Serum Amino Acids and Proteomics Profiles in Nursery Pigs Fed with Low-protein, -calcium, and -phosphorous Diets
Authors: Shili Cedrick N N , Habibi Mohammad , Goodarzi Parniyan , Kiyimba Frank , Hartsen Steve , Broomhead Jonathan N , Ramanthan Ranjith , Pezeshki Adel
Published: October 2021

Feeding pigs with very low-protein (VLP) and low-phosphorous (P) diets may be useful for decreasing the nutrients excretion to the environment; however, this practice negatively impacts the animals’ growth performance. A beneficial effect of corn-expressed phytase (CEP) on growth performance of pigs fed with VLP diets was shown by our group recently. Little is known whether this improvement is related with alterations in profile of blood proteins and amino acids (AA). The objective of this study was to investigate whether supplementation of VLP, low-calcium (Ca) and low-P diets with a CEP can influence the serum AA and proteomics profiles in pigs. Forty-eight weaned barrows were subjected into one of the following groups (n = 8/group) for 4 weeks: positive control (PC), negative control-reduced protein (NC), NC+low-dose CEP, i.e 2,000 FTU/kg (LD), NC+high-dose CEP, i.e. 4,000 FTU/kg (HD), LD with reduced Ca/P (LDR), and HD with reduced Ca/P (HDR). At week 4, blood samples were collected from all pigs. Compared to PC, NC reduced the serum leucine and phenylalanine concentrations; however, LD recovered their levels. Using trypsinolysis and mass spectrometry, 703 serum proteins were identified and quantified, wherein 25 were found to be differentially expressed among groups. Hierarchical clustering showed a clear separation in proteins identified among dietary groups. Compared to NC, 23 and 24 proteins were found to be differentially expressed in serum of LD and HD groups, respectively, with some important proteins in growth regulation such as SELENOP being upregulated and the IGFBP family being downregulated in these groups. A positive correlation was detected between growth and abundance of BGN, TLN1, PDLIM1 and COL1A2 that are involved in bone mineralization and muscle structure development. Thus, CEP improved the serum profile of some essential AA and affected the expression of proteins involved in regulation of growth in pigs fed with VLP diets.
221 Camelina Meal as an Alternative Ingredient in Growing-finishing Pig Diets
Authors: Hilbrands Adrienne , Li Yuzhi , Johnston Lee , Cox Ryan , Lazarus William , Martin Wayne , Forcella Franklin , Gesch Russ
Published: October 2021

The objective of this experiment was to determine the most effective inclusion rate of camelina meal (CM) in growing-finishing pig diets. Pigs (n = 192; 11 wk old), balanced for sex and initial weight, were assigned to 4 dietary treatments (6 pens/treatment; 8 pig/pen). Treatments consisted of a non-GMO corn-soybean meal-based control diet (CON), and CON containing 5% CM (5%CM), 10% (10%CM), or 15% (15%CM) camelina meal. Feed deliveries and pigs were weighed every other week to calculate ADG, ADFI, and Gain:Feed on a pen basis. Focal pigs (5/treatment) were harvested at 23 wk of age at the University of Minnesota abattoir for meat quality analysis (drip loss, pH, fat depth, belly firmness, loin marbling score, shelf life) and the remaining pigs were harvested at a commercial abattoir. Before harvest, real-time ultrasonic measurements of back fat depth and loin eye area were collected on all pigs. Data were analyzed using Proc Glimmix with dietary treatment as a fixed effect and pen as the experimental unit with data collected over time considered as repeated measures. Pigs fed CON diet consumed more feed than pigs fed CM diets (P = 0.002; Table 1). Pigs fed CON diet exhibited higher (P = 0.002) ADG than pigs consuming 10%CM and 15%CM diets. These differences resulted in heavier (P = 0.003) CON-fed pigs at marketing than 10%CM or 15%CM-fed pigs. There were no significant differences in Gain:Feed, any carcass or meat quality traits analyzed (data not shown). These results suggest that supplementing 5% CM in corn-soybean meal-based diets will not negatively influence growth performance, carcass traits, or meat quality of growing-finishing pigs.
238 Luteal Color Doppler Ultrasonography for Early Pregnancy Diagnosis in Postpartum Bos Taurus Beef Cows
Authors: Holton Matthew P , Oosthuizen Nicky , de Melo Gabriela , Davis Dylan B , Stewart R Lawton , Pohler Ky G , Lamb G Cliff C , Fontes Pedro L
Published: October 2021

The objective of this study was to evaluate the use of corpus luteum (CL) color doppler ultrasonography (CD) for early pregnancy diagnosis in Bos taurus beef cows and evaluate differences in CL blood perfusion among cows that experience late embryonic/early fetal mortality (LEM). Postpartum Bos taurus beef cows (n = 214) from three locations were exposed to a 7-d CO-Synch + CIDR protocol followed by fixed-time artificial insemination (day 0). On days 20 and 22, B-mode and CD ultrasonography were performed to evaluate CL morphometries and blood perfusion, respectively. Cows were considered non-pregnant when CL area was < 20 mm2 or estimated blood perfusion was ≤ 25%. Conventional ultrasonography on day 29 was utilized as the gold standard method. Pregnant cows had greater CL diameter, CL area, and CL volume when compared to non-pregnant cows on day 20 and 22 (P < 0.001; Table 1). Additionally, percentage of central, peripheral, and total luteal blood perfusion, as well as the respective blood perfusion scores were greater (P < 0.001) in pregnant compared with non-pregnant cows on both day 20 and 22. Sensitivity, specificity, positive predicted value (PPV), negative predicted value (NPV), and accuracy for the CD on day 20 were 100, 74, 81, 100, and 88%, respectively. Sensitivity, specificity, PPV, NPV, and accuracy for CD on day 22 were 100, 86, 89, 100, and 93%, respectively. Pairwise comparison of receiver operating characteristics curve analysis indicated no differences between CD on days 20 and 22 (P = 0.12). No differences in luteal blood perfusion were observed on day 20 or 22 among cows that maintained pregnancies compared with LEM cows (P ≥ 0.27). In conclusion, CD successfully detected most non-pregnant cows (81 and 89% on day 20 and 22, respectively) and false negative results were absent (NPV = 100%).
235 Uterine Function During Maternal Recognition of Pregnancy Differs Due to Size of the Ovarian Reserve in Beef Heifers
Authors: Cushman Robert A , Rosasco Shelby , Epperson Kaitlin M , Northrop-Albrecht Emmalee J , Rich Jerica J , Chase Chadwick , Miles Jeremy R , Crouse Matthew S , Perry George A , Summers Adam , Snider Alexandria
Published: October 2021

The relationship of ovarian reserve parameters to fertility in mammalian females continues to be debated. We demonstrated improved uterine function, creating an environment that is more supportive of early embryonic development in beef heifers with increased numbers of follicles. In the present study we hypothesized that timing of luteolysis differs between heifers with increased compared to heifers with diminished numbers of follicles. Angus heifers (n = 20/ group) were classified as low (14.7 ± 1.1) or high (32 ± 1.1) antral follicle number based on ovarian ultrasonography, and artificially inseminated (d0) following a Select Synch protocol. At d16 after insemination, heifers were slaughtered, and reproductive tracts collected. Tracts were flushed with 20 mL of physiological saline to determine pregnancy status by presence of a conceptus and endometrial samples from the horn ipsilateral to the CL were frozen for determination of transcript abundance. Real-time RT-PCR was performed to determine relative transcript abundance of oxytocin receptor (OXTR) and interferon-stimulated gene-15 (ISG15) with glyceraldehyde-3-phospate dehydrogenase as the endogenous reference gene. Transcript abundance was analyzed using the MIXED procedure of SAS with follicle group, pregnancy status and the interaction as fixed effects. Transcript abundance of ISG15 was greater in pregnant endometrium than non-pregnant endometrium (2.75 ± 0.25 vs 0.16 ± 0.22-fold; P < 0.0001) with no influence of follicle group or the interaction. The interaction of follicle group and pregnancy status influenced OXTR transcript abundance (P = 0.06). Luteolytic mechanisms were activated in non-pregnant heifers with diminished numbers of follicles (1.46 ± 0.25-fold) and were not activated in pregnant heifers (0.06 ± 0.22-fold) or heifers with increased numbers of follicles that were not pregnant (0.32 ± 0.30-fold). These data indicate a wider window of recognition of pregnancy in beef heifers with increased numbers of ovarian follicles. USDA is an equal opportunity provider and employer.
239 Increased Preovulatory Estradiol Improves Pregnancy Success of Embryo Transfer in Beef Cows
Authors: Ketchum Jaclyn , Perry George A , Epperson Kaitlin M , Quail Lacey , Ogg Makayla , Zezeski Abigail L , Rich Jerica J , Zoca Saulo Menegatti , Kline Adalaide C , Andrews Taylor , Ortega M Sophia , Smith Michael F , Geary Tom W
Published: October 2021

Preovulatory estradiol concentrations and expression of estrus have been associated with greater pregnancy rates in beef cattle following AI, thus an experiment was designed to determine if supplemental estradiol (E2) at GnRH-induced ovulation would improve pregnancy retention in postpartum beef cows after embryo transfer. Cows were synchronized with the 7-d CO-Synch + CIDR® protocol. On d0 (48h post-prostaglandin) cows were grouped by estrual status (Estrual; n=198, nonestrual; n=406). Nonestrual cows were administered GnRH and randomly assigned to either no treatment (Control; n=204) or administration of 0.1 mg (IM) estradiol 17-β (Estradiol; n=202). In a preliminary study, 0.1 mg (IM) estradiol 17-β increased plasma estradiol (17.11±3.4 pg/mL; P < 0.01) and remained elevated above baseline for approximately 8h compared to control (1.70±0.58 pg/mL). All cows received an in vivo produced embryo on d7. Embryos were matched by grade, stage, and flush across treatments. Pregnancy was classified on d30 by either plasma pregnancy-associated glycoproteins analysis (Year 1) or ultrasonography (Year 2). Plasma estradiol concentrations (d-2, d0h0, d0h2) were analyzed by PROC MIXED as repeated measures in SAS(9.4), while GLIMMIX procedures were used to analyze differences in pregnancy rates with treatment, group, year, and their interactions as fixed effects. There was a treatment by time interaction (P < 0.001) in E2 concentration. There was no difference in plasma E2 concentrations on d0h0 (P >0.30) between treatments. At d0h2, Estradiol cows (15.7±0.25 pg/mL) had greater plasma E2 compared to Estrual (4.0±0.13 pg/mL) or Control (3.4±0.25 pg/mL) cows (P < 0.001), and Estrual cows had greater plasma E2 than Control cows (P = 0.02). Control cows had decreased (26%) pregnancy rates compared to both Estradiol (37%; P = 0.03) and Estrual (40%; P = 0.01) cows. Pregnancy rates did not differ (P = 0.51) between the Estrual and Estradiol cows. In conclusion, elevated preovulatory concentrations of estradiol are critical for improved pregnancy retention following embryo transfer.
249 Effects of Maternal Nutrient Restriction During Late Gestation on Uterine Blood Flow and Placental Size in the Primiparous Bovine Dam
Authors: Redifer Colby A , Wichman Lindsey G , Meyer Allison M
Published: October 2021

To determine effects of late gestational maternal nutrient restriction (NR) on uteroplacental blood flow and placental growth, primiparous fall-calving crossbred beef heifers [BW: 451 ± 28 (SD) kg; BCS: 5.4 ± 0.7] were individually-fed either 100% (control; CON; n = 12) or 70% (n = 13) of energy and protein requirements for maintenance, pregnancy, and growth during the last 120 days of gestation. Transrectal color Doppler ultrasonography of both uterine arteries was conducted pre-treatment and every 21 d during treatments. Placentas were split into ipsilateral and contralateral sides, dissected (cotyledonary vs. intercotyledonary), and dried. Data were analyzed with treatment, treatment initiation date, and calf sex (when P < 0.25) as fixed effects. Uterine blood flow included day and treatment x day (repeated measures). Dam BW was less (P ≤ 0.01) from d 223 of gestation through parturition for NR dams, but calf BW was not affected (P = 0.72) by treatment. The interaction affected (P < 0.01) heart rate, where NR dams had decreased heart rate after treatments began. Treatment did not affect (P ≥ 0.20) uterine artery blood flow or hemodynamics, but all variables were affected (P ≤ 0.04) by day. Contralateral total and cotyledonary weights tended (P ≤ 0.09) to be greater and ipsilateral and total cotyledonary:intercotyledonary ratios were greater (P ≤ 0.01) for CON. Cotyledon number, cotyledon size, and total cotyledonary, intercotyledonary, and placental weight were not affected (P ≥ 0.15) by treatment. Relative to dam BW, uterine blood flow was not affected (P = 0.83), but relative placental weight tended to be greater (P = 0.09) in NR dams. In the current study, NR dams lost maternal BW during late gestation and had less contralateral placental growth, yet uterine blood flow was maintained and placental size relative to BW ensured fetal growth similar to CON offspring.
252 Impact of Pre- and Postnatal Nutritional Extremes on Tonic Secretion of Gonadotropins and Feedback Responsiveness to Estradiol in Sexually Mature Heifers
Authors: Garza Viviana , Kellerman Julie I , Maia Tatiane S , Cardoso Rodolfo C , Williams Gary L
Published: October 2021

Objectives were to test the hypotheses that nutritional extremes during prenatal development interact with postnatal nutrition during the juvenile period of heifers to impact 1) tonic secretion of gonadotropins, and 2) estradiol-17β (E2) negative and positive feedback responsiveness in adulthood. Heifers were selected from a larger population programmed nutritionally using a 3 x 2 factorial arrangement of pre- and postnatal diets. Beginning at 90 days of pregnancy, Bos indicus-influenced cows (n = 95) were fed to achieve body condition scores (BCS; 1–9 scale) of 3–3.5 (L; thin), 5.5–6 (M; moderate), or 7.5–8 (H; obese) by onset of the third trimester and maintained thereafter. Heifer offspring were weaned at 3–3.5 months of age and assigned to either a low- (L; 0.5 kg/day) or high-gain (H; 1.0 kg/day) diet until 8 mo. of age, then fed a common diet until puberty. Heifers (n = 18; 6/grp) representing HH, MH and LL combinations were ovariectomized postpubertally (17.1 mo. of age) and received E2 replacement. In Exp. 1, blood samples were collected at 10-min intervals to evaluate pulsatile secretion of LH and FSH for 5.5 hours. In Exp. 2, heifers received E2 (2.4 ug/kg I.M.), with blood sampling at 30-min to 1-h intervals for 30 h. Heifers in the MH (1.25 ± 0.11 ng/mL) group tended (P < 0.09) to have greater LH pulse amplitude compared to HH (0.91 ± 0.14 ng/mL) and LL (0.96 ± 0.09 ng/mL); otherwise, frequency, amplitude, and mean concentrations of LH and FSH did not differ among groups. Exogenous E2 (Exp. 2) suppressed (P < 0.0001) mean plasma concentrations of LH and FSH equally among groups, then stimulated equivalent surges of LH beginning at 14 ± 0.02 h, with only two FSH surges detected. Neither pre- nor postnatal nutrition affected E2 negative or positive feedback in this study.
259 The Role of Extracellular Vesicles in Mitigating the Effect of Heat Stress
Authors: Tesfaye Dawit
Published: October 2021

Environmental heat stress negatively affects the fertility of dairy cows by disrupting reproductive processes spanning from follicular development to maternal recognition of pregnancy. Investigation of cellular level responses to stress would contribute to the understanding of the mechanism behind survival responses. Extracellular vesicles (EVs), which carry biologically active signaling molecules, are reported to play a significant role in the cellular response to stress. They are produced by almost all types of cells and abundantly present in various biological fluids including follicular fluid, oviductal fluid, uterine fluids in vivo, and in spent culture media in vitro. Those EV-coupled molecular signals in biological fluids are indicative of the physiological status of the cells of their origin. This has been evidenced by the presence of EV-mediated miRNA signals in follicular fluid associated with the metabolic status of cows. Recent studies revealed the potential role of follicular fluid EVs in carrying molecular signals which can reverse or protect the damage incurred by heat stress in bovine oocytes. In addition to cellular defense responses (activation of HSP70 and HSP90, NRF2 and GRP78 & 94), bovine granulosa cells exposed to heat stress in vitro released EVs enriched with selected mRNA (HSP90 and SOD1) and miRNAs. Among others, miR-1246, miR-374a, and miR-2904 were found to be enriched in EVs released from granulosa cells exposed to thermal stress. Those miRNAs were found to regulate pathways related to heat and endoplasmic reticulum stress responses. The priming of recipient bovine granulosa cells by EVs derived from heat-stressed granulosa cells induced tolerance against recurrent heat stress. Collectively, EV-mediated molecular signals would provide another layer of cell-to-cell communication and deliver protective signals against oxidative stress to recipient cells. This would provide opportunities for future potential application of EVs in tackling oxidative stress-associated fertility problems in humans and animals.
263 Characterizing Vaginal Bacterial Community Composition in Brangus Heifers
Authors: Messman Riley D , Contreras-Correa Zully E , Paz Henry A , Lemley Caleb O
Published: October 2021

The role of the reproductive tract microbiota is an emerging field receiving considerable attention in human research, whereby the vaginal microbiota has been characterized in relation to fertility, conception, pregnancy, and parturition. However, the acidic, Lactobaccillus dominated vaginal microbiota in humans contrasts the neutral, dynamic microbial environment characterized in cattle. Over the past few years, many postpartum studies in dairy cattle described a mechanism recently proposed in humans, the ascension of the vaginal microbiota into the uterine body at the onset of labor. Although bovine fetal sterility prior to parturition is under debate, the vaginal microbiota is an early contact for the neonate with microorganisms and inoculates the uterus during parturition. Thus, any changes occurring in the vaginal microbiota could have implications in dam and calf health; this, combined with ease of access, led to the current research focusing on the bovine vaginal microbiota. Characterization studies during the estrous cycle, gestation, and postpartum period have been performed, concluding the bovine vaginal microbiota is dynamic. However, due to the low abundance in the vaginal microbiota, the seemingly small taxonomic changes reported in these studies could be of great importance. Secondly, researchers have begun to evaluate the effect of exogenous and endogenous hormone concentrations on the vaginal microbiota. Little to no differences have been found except with exogenous melatonin supplementation. In pregnant heifers, exogenous melatonin altered the beta diversity of the vaginal tract by increasing aerobic bacteria present. Moreover, a study evaluating the effects of nutrient restriction on the vaginal microbiota found no taxonomic or structure differences. These findings have allowed researchers to target paucities, improve methodology, and realize the importance of the reproductive tract microbiota. In short, based on these studies, future research examining the role of the reproductive tract microbiota could uncover mechanisms vital to increasing reproductive performance.
258 W112 Reproductive Performance in Domestic Ruminants: 50 Years of accomplishment: a USDA-NIFA Multistate Research Project
Authors: Shipka Milan P
Published: October 2021

This symposium acknowledges the founders of W112 Reproductive Performance in Domestic Ruminants. The contributions they made laid foundation collaborative efforts that continued over the next half century. The W112 really began in 1969 as a rewritten project involving several Agricultural Experiment Stations. That original project was W-49, that had been in existence at least as early as 1958. Upon approval of the project renewal in early 1970, the project was renamed W112 Reproductive Performance in Domestic Ruminants. The list of names of participants is like a who’s who of reproductive physiologists, too long to enumerate here. Increasing knowledge of physiology and endocrinology were paramount during the early years. Development, improvement, and sharing of analytical techniques improved accuracy of results, safety of procedures, and knowledge to be gained from the research. Concurrently, mechanistic basic and applied studies involving oocyte development, ovulation, sperm development, fertilization, pregnancy, and parturition all brought new understanding of the reproductive biology of domestic species. A good deal of what we currently know of the reproductive biology of ruminant animals finds some basis in laboratories involved in W112 collaborations. The unique nature of these scientists resulted from their mutual respect. Many young scientists found mentors in W112 that assisted us in developing our own research programs. And the support has not ended with research collaboration. It has been common for project participants to share teaching resources and serve on graduate student committees for each other’s students, fostering future involvement in the project. The W112 began slightly more than 50 years ago. Those of us who have been part of this group share a hope that the multistate project named Reproductive Performance in Domestic Ruminants will still be meeting the same goals of collaboration and support among scientists working to further animal agriculture for another 50 years and more.
261 Effects of Dam Nutrition on Offspring Metabolism
Authors: Govoni Kristen E
Published: October 2021

Maternal diet during gestation is important for proper fetal growth and development. There is evidence that poor maternal nutrition (restricted- and over-feeding) can alter growth of the fetus with long-term consequences on postnatal growth and adult maintenance. Additionally, maternal diet can program offspring for altered metabolism which leads to increased fat deposition and likely reduced efficiency of production later in life. Using livestock models, we and others have demonstrated insulin resistance, leptin resistance, and increased adiposity in response to poor maternal nutrition. These systemic changes are likely due to altered metabolic regulation at the tissue level. Using a sheep model, we have evidence that poor maternal nutrition also alters key metabolic profiles in muscle and liver, key metabolic tissues, in offspring. Specifically, in offspring of restricted-fed ewes, similar profiles of amino acid (e.g. branched-chain amino acids, histidine, methionine) and lipid (e.g. triglycerides) metabolites were altered in blood, liver, and muscle. In the muscle of offspring from restricted- and over-fed ewes, lipid and protein metabolic profiles diverged between the two treatment groups. This demonstrates different mechanisms contributing to altered metabolism of offspring from ewes restricted- and over-fed during gestation. The similar changes in metabolic profiles at both the systemic and local level suggest complex mechanisms involved in metabolic dysregulation of offspring from poorly fed mothers, which likely contribute to life-long metabolic dysregulation and reduced efficiency of growth and product quality.
267 Effect of Hay Type on the Winter Growth of Bos Grunniens Raised in Eastern Kentucky
Authors: Lehmkuhler Jeffrey W , Dike Gregory , McCarty Mary , Crites Benjamin
Published: October 2021

Bos grunniens (yak) have been utilized as a source of fiber, milk, dung, meat and transportation in the high-altitude regions of Asia for centuries. Limited research has been conducted on the species in North America. The objective of this on-farm research was to evaluate the effect of hay type on growth rate of growing yaks. Forages evaluated included alfalfa (A), orchardgrass-red clover (O) and a cool-season pasture grass species mixture (P). The experimental design was a partially balanced 3x3 Latin square with an extra pen. Yaks were stratified to pens by age and sex resulting in a pen of mixed sex (3 males/2 females) recently weaned calves, a pen of five yearling females, and two pens of five yearling males. Each period lasted for 45 days and animal weights were collected at the beginning and end to assess weight change and daily gain. Hay offered was weighed and feeding losses were visually estimated to determine hay DM disappearance. Forage samples were collected and analyzed for nutrient content. Data were analyzed using the PROC GLM procedure of SAS. No carryover effects were noted and means were separated using Tukey’s multiple comparison test where α=0.10. Forage type had a significant impact on period weight change of growing yaks during the winter with O having greater weight gain (9.5 kg) than P (-4.7 kg) with A being intermediate (8.5 kg). Forage DM disappearance when expressed as percent of body weight was greater for A (2.70) compared to P (2.25) while O (2.28) was not different from either. Forage type and quality can impact weight gain and forage disappearance during the winter months for growing yaks with higher quality forage providing greater weight gain.
272 Effect of Frame Size and Supplementation on Performance and Carcass Characteristics of Beef Cattle Finished on Novel Endophyte-infected Tall Fescue Pastures
Authors: Murray Adam R , Moore Richard L , Moore Mikayla F , Isengildina-Massa Olga , Greiner Scott P , Pent Gabriel J , Wilson Thomas B
Published: October 2021

Objectives were to investigate the effects of frame score (FS) and supplementation on performance and carcass characteristics of cattle finished on novel endophyte-infected fescue pastures. This 2-yr experiment used 80 Angus-sired, crossbred steers and heifers bred for divergent FS. Cattle were allotted to 5 treatments: 1) non-supplemented small frame (S-NON; FS = 3.0 ± 0.9), 2) supplemented small frame (S-SUPP), 3) non-supplemented large frame (L-NON; FS = 4.7 ± 0.6), 4) supplemented large frame (L-SUPP), and 5) grain-based control feedlot ration (CON; FS = 4.2 ± 0.6; target ADG = 1.36 kg/day). Daily rations were delivered individually using Calan gates. Pasture supplement contained corn gluten feed, a commercially available rumen-protected prilled vegetable fat, and dried molasses fed at 0.5% of BW. Treatments started on 7/8/2019 and 5/21/2020, and ended in November of each yr when cattle were slaughtered at a commercial abattoir. Results were analyzed using PROC MIXED of SAS with main effects of treatment, sire, sex, yr, and yr x treatment, with contrast statements comparing large vs. small frame, pasture supplemented vs. non-supplemented, and control vs. pasture groups. As expected, CON had greater (P < 0.001) growth performance (final BW and ADG) and carcass characteristics (HCW, subcutaneous fat, marbling, dressing percentage (DRESS%) than pasture groups, and tended to have greater (P=0.053) REA. Relative to pasture groups, CON had greater (P < 0.001) Minolta L* and a* lean tissue values, and decreased (P < 0.001) b* values for fat tissue. While non-supplemented cattle had decreased (P = 0.016) yield grades (YG), supplemented cattle had greater (P < 0.050) final BW, ADG, subcutaneous fat, HCW, marbling, and DRESS% compared to non-supplemented cattle. Small framed cattle tender to have decreased (P = 0.056) YG; but, large framed cattle had greater (P = 0.006) HCW, and tended (P = 0.060) to have greater ultrasound subcutaneous fat. Results support low-level supplementation in pasture-finishing systems to improve carcass value.
273 Effect of Bioadditives on the Bioproductive Behavior and Histomorphometric Changes of cobb-500 Chicks
Authors: Miranda José E , Astudillo Fabian , Marin Alfredo
Published: October 2021

The objective of this study was to evaluate the probiotic action of two bioadditives and their behavior on the bioproductive parameters and histomorphometric changes of CoBB-500 chickens, in the first 21 days of age. 450 Cobb-500 chicks were used, distributed in three groups of 150 animals each. Control (T1); microbial culture A (T2) and microbial culture B (T3). Substrate T2 (molasses-vinasse) fermented with Lactobacillus acidophillus, L. bulgariccus spp. T3 (molasses-vinasse) fermented with Saccharomyces cerevisiae and Kluyveromyces fragilis (L-4 UCLV). A completely randomized design was used to evaluate live weight, mean daily gain, diarrheal incidence, mortality, relative weight of the digestive tract organs, and histomorphometric changes. In the evaluations carried out at 21 days of age, the weight gain in the chicks that consumed biopreparations (T2 and T3) was higher (P> 0.05). Chickens that consumed biopreparation did not die during the study. The relative weight of the digestive tract organs was higher (P <0.001) in treatments T2 and T3. The length and width of the villi were better in groups T2 and T3 (P <0.05), the depth of the crypts was greater (P <0.05) in T1. Regarding the depth / length relationship of the villi T2 and T3 it was better (P <0.05). It concludes that the inclusion of biopreparations in chicken feed improves weight gain, development and growth of organs of digestive importance. Likewise, a reduction in the occurrence of diarrhea and animal mortality is achieved.
274 Comparison of Two Ultrasound Systems for Estimation of Carcass Attributes in Feedlot Steers
Authors: Jesko Noah P , Perkins Thomas L , Lawrence Ty E , Richeson John , Looney Charles
Published: October 2021

Sixty-eight (68) crossbred steers were evaluated using two real-time, B-mode ultrasound units to estimate final carcass attributes. The cattle were ultrasounded at the West Texas A&M research feedlot (Canyon, Texas) and carcass data was collected at the West Texas A&M Meats Laboratory (Canyon, Texas) or Tyson Fresh Meats (Amarillo, Texas). Objectives of the study were 1) to compare ultrasound live animal data to carcass attributes at harvest 2) to evaluate the performance differences between the ALOKA 500 (ALK) and the EVO ultrasound units All ultrasound images were captured by the same Ultrasound Guidelines Council (UGC) certified technician with images being processed at the UltraInsights Laboratory (Pierce, Colorado). The correlations between 12th rib fat thickness of the carcass (FTC) and ultrasound (FTU) were 0.84 for the ALK and 0.85 for the EVO, with no differences being found between the two units (P = 0.15). Correlations between the 12-13th rib carcass ribeye area (REAC) and ultrasound ribeye area (REAU) were 0.69 for the ALK and 0.66 for the EVO. There was no difference in REAU size between the two units. Carcass marbling score (MS) and ultrasound intramuscular fat (IMFU) correlations were 0.78 for the ALK and 0.84 for the EVO. The IMF data were found to be different between the two units, with the EVO measuring a mean IMFU value of 6.03 and the ALK a value of 5.26 with the change of 0.77 being different (P < 0.01). It is concluded that both ultrasound units performed favorably when predicting FTC and marbling score but were not highly correlated for REAU. It was found that the predictions between the two units on FT and REA were the same, though the EVO was higher on both. The IMFU values between the ALK and EVO were different, with the EVO again predicting higher values.
269 Validation of an Automatic Scale Equipped with Solar Panels for Grazing Beef Cattle
Authors: Pancini Stefania , Pent Gabriel J , White Robin R , Goncherenko Guillermo , Wege Dias Nicholas W , Haines Hannah , Mercadante Vitor R G
Published: October 2021

Body weight (BW) is used to detect health and nutritional disorders in cattle, as well as calculate profitability of the production system based on weight gain curves. In grazing systems, measuring BW frequently implies moving animals, which is labor intense, stressful, and reduces grazing time and feed intake. All of which negatively impacts animal performance. An automated scale in the pasture can reduce labor and animal handling, while ensuring an accurate BW estimation. Our objective was to evaluate the functionality and accuracy of an automatic wireless scale system equipped with solar panels (SmartScale, C-LOCKTM), when compared to a conventional scale located at the cattle working facility. Eight multiparous beef cows were weighed in a 14-day interval for a period of 57 days with a conventional scale, while at the same time BW was measured daily with an automated scale located at the pasture in front of the water trough. This wireless system registers BW every time the animal approaches the water trough and automatically transmit it to a server via cellular network. Correlation between weighing systems was evaluated through a linear regression (R Core Team, 2019), where the adjusted R2 value was 0.99, determining an excellent linear relationship between values obtained by the conventional scale and values obtained by the automated scale. In addition, the automated scale registered the time of day, time spent in the scale, and number of daily visits. The probability to find an animal at the scale varies between 15% to 20% during daylight, decreasing under 9% during the night, with 2.56±1.50 average number of visits per day, where animals spend in average 2.94±1.84 minutes. In conclusion, the automated scale has the ability to measure BW with great precision and has potential to be used as a complimentary instrument to evaluate animal behavior in grazing systems.