Aging increases lightness of grass-fed beef.

Grass-fed beef is becoming increasingly popular and is expected to be a $14 billion industry by 2024. Even so, grass-fed beef is typically darker in appearance than that of conventional grain-fed beef. Aging has been shown to improve lean color (*, *) of dark-cutting beef however little work has focused on aging as it relates to improving the lean color of grass-fed beef.

Determining muscle plasticity and meat quality development of low-input extended fed market-ready steers.

In March 2020, the World Health Organization declared COVID-19 a pandemic, which ultimately led to many meat processors temporarily shutting down or reducing processing capacity. This backlog in processing capacity forced many feedlots to retain cattle for longer periods of time and assume the risk of major market fluctuations. The aim of this study was to understand how a dietary insult affects meat quality and muscle metabolism in market-ready steers (590 kg).

Intravenous Injection of Sodium Hyaluronate Diminishes Basal Inflammatory Gene Expression in Equine Skeletal Muscle.

Following strenuous exercise, skeletal muscle experiences an acute inflammatory state that initiates the repair process. Systemic hyaluronic acid (HA) is injected to horses routinely as a joint anti-inflammatory. To gain insight into the effects of HA on skeletal muscle, adult Thoroughbred geldings (n = 6) were injected with a commercial HA product weekly for 3 weeks prior to performing a submaximal exercise test.

A Carnitine-Containing Product Improves Aspects of Post-Exercise Recovery in Adult Horses.

Strenuous exercise can cause tissue damage, leading to an extended recovery period. To counteract delayed post-exercise recovery, a commercial product containing L-carnitine (AID) was tested in adult horses performing consecutive exercise tests to exhaustion. Fit Thoroughbreds were administered an oral bolus of placebo (CON) or AID prior to performing an exercise test to exhaustion (D1).

Molecular and biochemical regulation of skeletal muscle metabolism.

Skeletal muscle hypertrophy is a culmination of catabolic and anabolic processes that are interwoven into major metabolic pathways, and as such modulation of skeletal muscle metabolism may have implications on animal growth efficiency. Muscle is composed of a heterogeneous population of muscle fibers that can be classified by metabolism (oxidative or glycolytic) and contractile speed (slow or fast). Although slow fibers (type I) rely heavily on oxidative metabolism, presumably to fuel long or continuous bouts of work, fast fibers (type IIa, IIx, and IIb) vary in their metabolic capability and can range from having a high oxidative capacity to a high glycolytic capacity.

The initial delay to mitotic activity in primary cultures of equine satellite cells is reduced by combinations of growth factors.

Satellite cell (SC) activation is defined as the time frame during which the stem cell becomes poised to reenter G1 of the cell cycle. The growth factors and events leading to full mitotic activation in equine SCs remain largely unknown. Insulin-like growth factor I (IGF-I), hepatocyte growth factor (HGF), and fibroblast growth factor 2 (FGF2) are sequentially transcribed during the muscle repair and recovery period following strenuous exercise in adult horses.

Short Communication: Supplementation with calcium butyrate causes an increase in the percentage of oxidative fibers in equine gluteus medius muscle.

Optimal athletic performance requires meeting the energetic demands of the muscle fibers, which are a function of myosin ATPase enzymatic activity. Skeletal muscle with a predominant oxidative metabolism underlies equine athletic success. Sodium butyrate, a short-chain fatty acid, can affect muscle fiber composition in pigs.

β-Hydroxy β-methylbutyrate supplementation to adult Thoroughbred geldings increases type IIA fiber content in the gluteus medius.

Consumption of β-hydroxy β-methylbutyrate (HMB) alters muscle composition and metabolism leading to strength and agility improvements in human athletes. To determine if HMB affects athletic performance and muscle function in horses, Thoroughbred geldings were fed a control (CON; n = 5) or HMB (n = 6) supplement for 6 wk prior to completing a standardized exercise test (SET). Gluteus medius (GM) muscle biopsies were obtained before the SET for fiber typing.

Effects of mid-gestational l-citrulline supplementation to twin-bearing ewes on umbilical blood flow, placental development, and lamb production traits.

The objective of the study was to examine how l-citrulline supplementation to ewes during mid-gestation influences placental activity, placental blood flow, lamb body weight, and carcass characteristics. Two studies were completed. A pharmacokinetic study to compare circulating plasma amino acid concentrations after a single intravenous injection of 155 µmol/kg BW l-citrulline or after an isonitrogenous amount of l-alanine (control; 465 µmol/kg BW).

Satellite cells and their regulation in livestock.

Satellite cells are the myogenic stem and progenitor population found in skeletal muscle. These cells typically reside in a quiescent state until called upon to support repair, regeneration, or muscle growth. The activities of satellite cells are orchestrated by systemic hormones, autocrine and paracrine growth factors, and the composition of the basal lamina of the muscle fiber.

Dietary tributyrin supplementation and submaximal exercise promote activation of equine satellite cells.

Postexercise skeletal muscle repair is dependent on the actions of satellite cells (SCs). The signal(s) responsible for activation of these normally quiescent cells in the horse remain unknown. The objective of the experiment was to determine whether submaximal exercise or tributyrin (TB) supplementation is sufficient to stimulate SC activation.

Impact of fetal vs. maternal contributions of Bos indicus and Bos taurus genetics on embryonic and fetal development1.

To evaluate how the inclusion of Bos indicus genotype influences early fetal development in cattle, a reciprocal embryo transfer approach was used in a completely randomized design with a 2 × 2 × 2 factorial arrangement of treatments to generate 55 pregnancies over 2 consecutive years (n = 55). Recipient cows were randomly assigned to (i) a diet that met daily energy maintenance requirements (MAINT) or (ii) a diet that restricted intake to 70% of the energy maintenance requirements (RESTR). Angus (AN) and Brangus (BN) embryo donors were superovulated and artificially inseminated with female sexed-sorted semen from the same breed.

Growth factor modulation of equine trophoblast mitosis and prostaglandin gene expression.

 To provide insight into maternal recognition of pregnancy control in equids, the mitogenic and developmental effects of endometrium-expressed growth factors (epidermal growth factor (EGF), fibroblast growth factor 2 (FGF2), hepatocyte growth factor (HGF), and insulin-like growth factor-1 (IGF-1)) were examined in equine iTr cells, an equine trophectoderm cell line. Initial western blots revealed that HGF and IGF-1 stimulate phosphorylation of AKT serine/threonine kinase 1 (AKT1) and EGF, FGF2, or HGF resulted in phosphorylation of both extracellular signal-regulated kinase 1 (ERK1) and ERK2. Mitotic activity was stimulated (P < 0.

Oxytocin is involved in steroid hormone-stimulated bovine satellite cell proliferation and differentiation in vitro.

Sex steroid hormones are used in the meat industry due to their ability to regulate muscle hypertrophy. However, the mechanisms underlying their action are not fully elucidated. Recent reports demonstrate that steroid hormones increase oxytocin (OXT) expression in skeletal muscle, indicating that OXT may play a role in satellite cell activity.

Decreased abundance of eIF4F subunits predisposes low birth weight neonatal pigs to reduced muscle hypertrophy.

Muscle hypertrophy is limited in low birth weight (LBWT) neonates, suggesting a reduction in protein synthesis and increased protein degradation. Sixteen pairs of one-day-old normal birth weight (NBWT) and LBWT littermates ( = 16) were euthanized, and the longissimus dorsi (LD) was sampled for protein abundance and kinase phosphorylation profile measures. Eukaryotic initiation factor (eIF)4E and eIF4G abundance, and assembly of the active eIF4E-eIF4G complex, was less for LBWT than for NBWT pig muscles.

Hepatocyte growth factor acts as a mitogen for equine satellite cells via protein kinase C δ-directed signaling.

Hepatocyte growth factor (HGF) signals mediate mouse skeletal muscle stem cell, or satellite cell (SC), reentry into the cell cycle and myoblast proliferation. Because the athletic horse experiences exercise-induced muscle damage, the objective of the experiment was to determine the effect of HGF on equine SC (eqSC) bioactivity. Fresh isolates of adult eqSC were incubated with increasing concentrations of HGF and the initial time to DNA synthesis was measured.

Downregulated Translation Initiation Signaling Predisposes Low-Birth-Weight Neonatal Pigs to Slower Rates of Muscle Protein Synthesis.

Low-birth-weight (LBWT) neonates experience restricted muscle growth in their perinatal life. Our aim was to investigate the mechanisms that contribute to slower skeletal muscle growth of LBWT neonatal pigs. Twenty-four 1-day old male LBWT (816 ± 55 g) and normal-birth-weight (NBWT; 1,642 ± 55 g) littermates ( = 12) were euthanized to collect blood and longissimus dorsi (LD) muscle subsamples.

Reduced skeletal muscle fiber size following caloric restriction is associated with calpain-mediated proteolysis and attenuation of IGF-1 signaling.

Caloric restriction decreases skeletal muscle mass in mammals, principally due to a reduction in fiber size. The effect of suboptimal nutrient intake on skeletal muscle metabolic properties in neonatal calves was examined. The longissimus muscle (LM) was collected after a control (CON) or caloric restricted (CR) diet was cosnumed for 8 wk and muscle fiber size, gene expression, and metabolic signal transduction activity were measured.

Diminished satellite cell fusion and S6K1 expression in myotubes derived from skeletal muscle of low birth weight neonatal pigs.

Low birth weight (LBWT) is consistently associated with impaired postnatal muscle growth in mammals. Satellite cell (SC)-mediated myonuclear incorporation precedes protein accumulation in the early stages of postnatal muscle development and growth. The objective of this study was to investigate proliferation and differentiation of SCs and the regulation of protein synthesis signaling in response to insulin-like growth factor (IGF)-I stimulation in SC-derived myotubes of LBWT neonatal pigs.

Tissue organization alters gene expression in equine induced trophectoderm cells.

Rapid morphological and gene expression changes occur during the early formation of a mammalian blastocyst. Critical to successful retention of the blastocyst and pregnancy is a functional trophectoderm (TE) that supplies the developing embryo with paracrine factors and hormones. The contribution of TE conformational changes to gene expression was examined in equine induced trophoblast (iTr) cells.

The influence of postnatal nutrition on reproductive tract and endometrial gland development in dairy calves.

Uterine gland development occurs after birth in cattle and other mammals. The timeline of gland development has been described in various species, but little is known about how postnatal diet influences uterine gland development. This is especially concerning in dairy heifers, where a variety of milk replacer and whole milk nutrition options exist.