All-trans retinoic acid (ATRA) has been associated with various physiological phenomenon in mammalian adipose tissue and skeletal muscle. We hypothesized that ATRA may affect skeletal muscle fiber type in bovine satellite cell culture through various transcriptional processes. Bovine primary satellite cell (BSC) culture experiments were conducted to determine dose effects of ATRA on expression of genes and protein levels related to skeletal muscle fiber type and metabolism. The semimembranosus from crossbred steers (n = 2 steers), aged approximately 24 months, were used to isolate BSC for 3 separate assays. Myogenic differentiation was induced using 3% horse serum upon cultured BSC with increasing doses (0, 1, 10, 100, 1000 nM) of ATRA. After 96 h of incubation, cells were harvested and used to measure the gene expression of protein kinase B (Akt), AMP-activated protein kinase alpha (AMPK), glucose transporter 4 (GLUT4), myogenin, lipoprotein lipase (LPL), myosin heavy chain (MHC) I, MHC IIA,MHC IIX, insulin like growth factor -1 (IGF-1), Peroxisome proliferator activated receptor gamma (PPARγ), PPARδ, and Smad transcription factor 3 (SMAD3) mRNA relative to ribosomal protein subunit 9 (RPS9). The mRNA expression of LPL was increased (P < 0.05) with 100 and 1000nM of ATRA. Expression of GLUT4 was altered (P < 0.05) by ATRA. The treatment of ATRA (1000nM) also increased (P < 0.05) mRNA gene expression of SMAD3. The gene expression of both PPARδ and PPARγ were increased (P < 0.05) with 1000nM of ATRA. Protein level of PPARδ was also affected (P < 0.05) by 1000nM of ATRA and resulted in a greater (P < 0.05) protein level of PPARδ compared to CON. All-trans retinoic acid (10nM) increased gene expression of MHC I (P < 0.05) compared to CON. Expression of MHC IIA was also influenced (P < 0.05) by ATRA. The mRNA expression of MHC IIX was decreased (P < 0.05) with 100 and 1000nM of ATRA. In muscle cells, ATRA may cause muscle fibers to transition towards the MHC isoform that prefers oxidative metabolism, as evidenced by increased expression of genes associated with the MHC I isoform. These changes in MHC isoforms appeared to be brought about by changing PPARδ gene expression and protein levels.

Neutral detergent fiber (NDF) and acid detergent fiber (ADF) composition have been shown to predict in vitro true digestibility (IVTD), in vitro NDF digestibility (IVNDFD), and in vitro ADF digestibility (IVADFD) in ruminants. This study’s objective was to estimate in vitro digestibility measures within the Daisy^II incubator using equine fecal inoculum from feedstuff NDF and ADF composition. Analyzed feedstuffs included alfalfa hay (Medicago sativa), Coastal Bermudagrass hay, soybean meal, rice bran, hempseed meal, and Bluebonnet® Equilene® Pellets. Data were analyzed using Akaike’s information criterion (AIC) within the R Statistical Program©. The highest ranked model for IVTD was the interaction of NDF and ADF: 10003.32 – 0.2904 × NDF − 0.4220 × ADF − 0.0010 × NDF × ADF (Adjusted R² = 0.959 and AICc = 474.97). Sample IVNDFD was moderately predicted by ADF: 855.15 – 1.5183 × ADF (Adjusted R² = 0.749 and AICc = 560.82). Feedstuff ADF produced the highest ranked model for IVNDFD: 881.91 – 1.5952 × ADF (Adj. R² = 0.835 and AICc = 541.33). These results indicate the effectiveness of using feedstuff NDF and ADF composition to predict IVTD, IVNDFD, and IVADFD within equine fecal inoculum. The findings of this study provide better understanding of feedstuff digestibility using equine fecal inoculum, but more research is warranted for validation of the models and the potential impact in vivo.

Yearling rough-stock bulls (n = 38) were utilized in a randomized complete block design to evaluate dietary hempseed meal (HSM) inclusion on growth (ADG), intake (DMI), and efficiency (F:G). Bulls were blocked by body weight (BW), grouped into 10 pens (n = 3–4 bulls/pen), and randomly assigned to an HSM or control supplement treatment (CON; 72.5% cottonseed meal, 14.5% soy hulls, 13% fat). Treatments were offered at 10%, while 90% was fed as a mixed ration [50% Bermuda grass hay, 40% textured commercial feed (10% CP)]. Diet samples were dried and DMI was calculated. F:G was evaluated using DMI and ADG. Blood for plasma analysis and BW were obtained on sample days, prior to feed delivery. Data were analyzed using the GLIMMIX procedure in SAS version 9.4. The results were considered significant when p ≤ 0.050. There was no treatment × time interaction, or treatment effect for interim BW, ADG, or F:G (p ≥ 0.100). A treatment × time interaction occurred for DMI (p < 0.01), and BW (p = 0.01) increased in all bulls over time, while ADG decreased (p = 0.005), suggesting that interim live performance was not affected by HSM. Plasma urea nitrogen increased over time (p < 0.001) in all bulls, with greater concentrations observed in HSM bulls (p = 0.043).

The objective of this study was to evaluate the effects of breed, lactation number, and lameness on lying time, milk yield, milk urea nitrogen concentration (MUN), progesterone concentration (P₄), and the calving-to-conception interval (CCI) of lactating dairy cows in Central Texas. A total of 84 lactating dairy cows (Holsteins, Jerseys, and crossbreeds) from a commercial dairy farm in Central Texas were randomly selected and enrolled in this study from October 2023 to February 2024. Cows (60 ± 7 DIM) were enrolled in cohorts weekly for five weeks and were randomly fitted with an IceQube pedometer (IceRobotics, Edinburgh, UK) to track lying time. Lameness and body condition scores (BCS) were recorded, and blood samples were collected once a week. Parameters of reproductive performance included insemination rate, conception rate, pregnancy rate, and the CCI. Monthly dairy herd improvement association (DHIA) testing included milk yield and MUN concentrations. Breed and lactation number had a significant effect on milk yield, MUN concentration, lying time, BCS, and lameness (p < 0.001). Lactation number had a significant effect on P₄ concentrations (p < 0.001). There was a positive correlation between lameness and milk yield (p = 0.014) and a negative correlation between lameness and MUN concentrations (p = 0.038).

Manure management costs are a substantial component of overall costs on a modern dairy farm. Due to the slim margins of contemporary milk production operations, dairies are under constant pressure to increase milking herd sizes to take advantage of size economies that enable them to compete in the global marketplace. This study provides a current assessment of manure management and overall costs and returns on four standard sizes of dairies typical of the southern Great Plains, particularly north central Texas. The study is necessitated by the fact that the changing economic landscape has resulted in substantial changes in manure management practices. This study also forms the basis for additional analyses that will explore alternative value-added options for dairy manure management. We utilize the Farm-level Economic Model to holistically simulate the costs and returns of four representative dairy herd sizes—small (300 cows), medium (720 cows), large (1500 cows), and very large (5000 cows). Based on prevailing assumptions about land areas farmed and farm management practices, we find that dairy farms require between 0.18 and 0.4 ha/cow to manage manure based on crop nitrogen uptake rates, versus 0.67 to 0.95 ha/cow for crop phosphorus uptake rates. Manure application costs alone range from USD 55/cow (USD 225/ha) to USD 115/cow (USD 300/ha) depending on dairy size, but some of these costs are offset by fertilizer cost savings. Proportion of manure hauled offsite ranges from 9% to 67% for phosphorus-based applications, depending on herd size, and net incomes per cow are reduced by USD 60 to USD 100 (USD 4.33 to USD 8.27 per Mg of milk) if manure is applied based on phosphorus uptake rates as compared to nitrogen uptake rates of receiving crops. Generating a broad array of economically viable value-added product options from dairy manure would enable farmers to be more competitive in a market characterized by thin margins.