Evaluation of particle size and feed form on performance, carcass characteristics, nutrient digestibility, and gastrointestinal tract development of broilers at 39 d of age.

The objective of this study was to evaluate combined effects of corn particle size and feed form on performance, carcass characteristics, nutrient digestibility, and gastrointestinal tract development of broilers from 1 to 39 d of age. A total of 1,800 days old, male Cobb 500 broilers were randomly assigned to 9 dietary treatments with 8 replicate pens (25 birds/pen). The experiment consisted of a factorial arrangement of 3 corn particle sizes (750, 1,150, and 1,550 µm) and 3 feed forms (mash, 3- and 4-mm pellets) provided from 1 to 39 d. Titanium dioxide (TiO2) was added as an indigestible marker (0.5%) during the finisher phase (27-39 d) to determine nutrient digestibility. Feed intake (FI), body weight (BW), and feed conversion ratio (FCR) were determined at 17, 27, and 39 d of age, with FCR adjusted for mortality. On d 40, 10 birds/pen were randomly selected and processed for meat yield determination. Data were analyzed as a 3×3 factorial (particle size x feed form) arrangement of treatments. Broilers fed 3- and 4-mm pellets had increased (P < 0.05) BW, FI, and lower FCR than broilers fed mash diets at 39 d of age. At 39 d of age, broilers fed diets with 750 µm corn particle size had heavier (P < 0.05) BW and increased FI than broilers fed diets with corn particle sizes of 1,150 and 1,550 µm. At 39 d of age FCR was unaffected by corn particle size. Heavier (P < 0.05) carcass and breast weights were observed for broilers fed 3-mm pellets. Broilers fed diets with corn particle size of 750 µm had heavier (P < 0.05) carcass and breast weight than broilers fed diets with 1,550 µm. Digestibility of nutrients was higher (P < 0.05) in pelleted diets, particularly when corn particle size was increased from 750 to 1,550 µm. Breast myopathies such as wooden breast (WB) and spaghetti meat (SM), were greater (P < 0.05) in broilers fed 3-mm pellets compared to mash diets. In conclusion, broilers fed 3- and 4-mm pelleted diets had greater nutrient digestibility and improved broiler performance compared to broilers fed mash diets.

Graduate students' perspectives on the role of faculty advisors in helping students with mental health problems.

Objective: Graduate students are more likely to experience mental illness than their peers in the general population. One potential source of support for personal issues and/or mental illness is a graduate student's faculty advisor. Although the relationship between faculty advisors and graduate students can positively influence the success and overall well-being of graduate students, graduate students may be reluctant to disclose mental health issues to their advisors. This study explores graduate students' perspectives on factors that influence their decision to disclose, or not to disclose, personal mental health information to their faculty advisor. Participants: The participants for this study were 28 graduate students from three universities in the southern United States. Methods: Four semi-structured focus groups were conducted over Zoom. Results: Thematic analysis of a series of focus groups with graduate students identified several consistent themes related to this disclosure decision-making process. Conclusions: Results have implications for mental health literacy and interpersonal communication interventions for those charged with mentoring graduate students.

Impact of every-day versus skip-a-day feeding of broiler breeder pullets during rearing on body weight uniformity and reproductive performance.

Genetic selection for increased growth rate in broilers makes feed restriction programs such as skip-a-day (SAD) feeding, for broiler breeders essential to managing body weight, flock uniformity, and reproductive performance. The objective of this experiment was to compare intestinal development, weight gain of breeder pullets, and reproductive performance (22-45 wk) when fed a high fiber diet (3.8% crude fiber) on either an every-day (ED) or SAD basis during rearing. The same developer ration and feed amounts were fed to both treatments. Day-old Ross 708 pullet chicks (n = 912) were randomly distributed into 4 floor pens (n = 228/pen, 2 pens/treatment). At 20 wk of age all birds were weighed, and the coefficient of variation (CV) and average body weight was calculated for each treatment. Birds were then distributed into 10 lay pens (n = 35 birds/pen, 5 pens/treatment) at 21.5 wk of age. Light was increased from 8 h to 15.25 h at move to the lay facility, and all birds were daily fed for the remainder of the study. Data were analyzed by SAS SLICE using a significance level of P ≤ 0.05. During lay, 25% of the birds from each treatment were weighed weekly to adjust feed and monitor body weight. At 21 wk the ED fed pullets were more uniform (P = 0.0007) than the SAD fed pullets. Eggs were collected daily and set for hatch every 4 wk from 28 to 42 wk of age. No significant difference in the hatch data were observed. The ED fed birds achieved first egg at 166 d of age while the SAD fed birds achieved first egg at 173 d of age. Specific gravity was measured every 2 wk from 30 to 40 wk, with ED reared birds having better overall eggshell quality (P = 0.02) and greater egg weight (P < 0.0001) than those fed SAD. Feeding a high fiber diet on an ED basis during rearing, improved body weight uniformity in rearing, encouraged early lay, improved eggshell quality and increased egg weight.

Effect of incubator tray location on broiler chicken growth performance, carcass part yields, and the meat quality defects wooden breast and white striping.

Large variations in hatching egg incubation temperatures have been previously shown to negatively impact posthatch growth in broiler chickens. The objective was to determine whether small incubation temperature variations owing to incubator tray location (LOC) could alter posthatch female and male broiler growth performance and carcass characteristics. Broiler hatching eggs were obtained from a 40-week-old commercial broiler breeder flock and incubated in trays placed in the bottom (BOT), middle (MID), and top (TOP) thirds of the racks (n = 4 racks per incubator tray LOC) in a single-stage incubator in a commercial hatchery. Chicks hatched from the 3 LOC (n = 720 per LOC) were vent sexed, vaccinated, and separate-sex reared with 12 birds per pen in a floor-pen facility and fed a common corn and soybean meal-based diet for 41 d. At day 41, all birds (n = 720) were processed to determine carcass and carcass part yields and incidence and severity of the meat quality defects wooden breast (WB) and white striping (WS). No LOC × Sex interactions were observed (P > 0.05). Growth performance and incidence and severity of WB and WS were similar among LOC (P > 0.05). However, broilers from BOT trays had heavier tender and breast weights than broilers from warmer MID trays (P < 0.05). Broilers from the BOT trays had higher breast meat yield as a proportion of carcass weight (25.00%) than warmer MID (24.54%) broilers (P < 0.05). However, broilers from warmer MID trays had greater carcass yield than those from cooler TOP trays (P < 0.05). As expected, male broilers had heavier carcass, breast, tender, wings, drumsticks and thighs weights and were more severely affected by WB than females (P < 0.05). Overall, these data indicate that the inherent differences in environmental factors among incubation LOC can impact broiler carcass and breast meat yields.

Distinguishing Extravascular from Intravascular Ferumoxytol Pools within the Brain: Proof of Concept in Patients with Treated Glioblastoma.

BACKGROUND AND PURPOSE: Glioblastoma-associated macrophages are a major constituent of the immune response to therapy and are known to engulf the iron-based MR imaging contrast agent, ferumoxytol. Current ferumoxytol MR imaging techniques for localizing macrophages are confounded by contaminating intravascular signal. The aim of this study was to assess the utility of a newly developed MR imaging technique, segregation and extravascular localization of ferumoxytol imaging, for differentiating extravascular-from-intravascular ferumoxytol contrast signal at a delayed 24-hour imaging time point. MATERIALS AND METHODS: Twenty-three patients with suspected post-chemoradiotherapy glioblastoma progression underwent ferumoxytol-enhanced SWI. Segregation and extravascular localization of ferumoxytol imaging maps were generated as the voxelwise difference of the delayed (24 hours) from the early (immediately after administration) time point SWI maps. Continuous segregation and extravascular localization of ferumoxytol imaging map values were separated into positive and negative components. Image-guided biologic correlation was performed. RESULTS: Negative segregation and extravascular localization of ferumoxytol imaging values correlated with early and delayed time point SWI values, demonstrating that intravascular signal detected in the early time point persists into the delayed time point. Positive segregation and extravascular localization of ferumoxytol imaging values correlated only with delayed time point SWI values, suggesting successful detection of the newly developed extravascular signal. CONCLUSIONS: Segregation and extravascular localization of ferumoxytol MR imaging improves on current techniques by eliminating intrinsic tissue and intravascular ferumoxytol signal and may inform glioblastoma outcomes by serving as a more specific metric of macrophage content compared with uncorrected T1 and SWI techniques.

Asymptomatic COVID-19: What the Neuroradiologist Needs to Know about Pulmonary Manifestations.

Coronavirus disease 2019 (COVID-19) is an infectious disease with a high asymptomatic incidence. Asymptomatic infections within a population will inevitably lead to diagnosis via unrelated medical imaging. We report the case of an asymptomatic patient undergoing a spine CT examination for trauma who was incidentally found to have lung abnormalities later confirmed to be COVID-19. We aim to familiarize neuroradiologists with the spectrum of COVID-19 pulmonary manifestations that are likely to be observed on neck and spine CT imaging.

Broiler chicken myofiber morphometrics and myogenic stem cell population heterogeneity1,2.

Myogenic stem cells (MSC), also known as satellite cells, play a key role in mediating post-hatch skeletal muscle growth in broiler chickens. Information regarding the heterogeneity of MSC populations and myofiber size distributions in different muscles of modern broiler strains of both sexes is scarce. Thus, myofiber cross-sectional area (CSA) and myogenic regulatory factor expression by MSC populations in 2 functionally different muscles (Biceps femoris, BF and Pectoralis major, PM) from both sexes of broilers from 2 strains, Ross 708 x Ross 708 (ROSS; Aviagen Group, Huntsville, AL) and Red Ranger (RR; S&G Poultry, Clanton, AL) was evaluated. Female and male broilers from both strains (n = 80 birds per strain) were reared for 43 d on a common corn and soybean meal-based diet. At 43 d of age, 8 birds per sex per strain (n = 32 total) were euthanized and PM and BF muscle samples from each bird were analyzed using cryohistology, immunofluorescence (IF) staining, and fluorescence microscopy. Cryosections from each muscle from each bird were IF stained to detect Myf-5, MyoD, and Pax7-expressing MSC. The CSA of every fiber in each digital image was measured and MSC populations (Myf-5+, MyoD+, Pax7+, Myf-5+: MyoD+, Myf-5+: Pax7+, MyoD+: Pax7+, and Myf-5+: MyoD+: Pax7+) were enumerated. Myofiber CSA was similar among the 2 strains and 2 sexes (P > 0.05). As expected, mean myofiber CSA was greater in the predominantly fast-twitch PM than the predominantly slow-twitch BF muscle (P = 0.006). At 43 d of age, ROSS broilers had a 32% larger population of Myf-5+: MyoD+: Pax7+ MSC compared with RR (P = 0.04). The heterogeneity of MSC was similar among the sexes. While the total MSC population was larger in the BF muscle compared with the PM (P < 0.05), the Myf-5+ and Pax7+ MSC densities were similar among muscles (P > 0.05). The major differences in myofiber morphometrics and MSC heterogeneity were not among the different broiler strains or sexes but were instead, between the 2 functionally different muscles.

Skeletal muscle growth characteristics and myogenic stem cell activity in broiler chickens affected by wooden breast.

The degenerative myopathy known as wooden breast (WB) has been increasingly observed in the breast muscle (PM) of commercial broilers during the last decade. Previous research has demonstrated that WB may be induced or ameliorated by modulating dietary digestible Lys (dLys) concentrations. Two concurrent experiments (Exp) were conducted to verify the effects of feeding 2 diets formulated to 75% and 100% of recommended dLys concentrations from 15 to 25 d of age on production responses and WB incidence (Exp 1), and the characterization of muscle stem cell activity in broilers affected by WB (Exp 2). At 25 and 43 d of age, birds were injected with 5΄-bromo-2΄-deoxyuridine (BrdU) prior to the collection of PM tissue to label mitotically active cells. Muscle samples were processed for cryosectioning and immunofluorescence staining and microscopy in order to determine myofiber cross-sectional area (CSA), to enumerate Myf-5+ and Pax7+ myogenic stem cell populations, and to determine the mitotic activity (BrdU+) of these populations. The reduced dLys diet produced broilers with differing (P < 0.001) incidences of WB within the same flock (Exp 1), with some detrimental effects on performance and processing characteristics. In Exp 2, broilers with severe WB had increased numbers (P = 0.016) and proportions (P = 0.022) of mitotically active, myogenic stem cells, as well as increased proportions (P < 0.05) of large CSA myofibers relative to broilers unaffected by WB at 25 d of age. At 43 d of age, broilers affected by severe WB had a greater (P = 0.011) total population of myogenic stem cell types (Myf-5+, Pax7+, or Myf-5+:Pax7+) and a concurrent increase (P = 0.007) in the mitotic activity (Myf-5+:BrdU+, and Pax7+:BrdU+, and Myf-5+:Pax7+:BrdU+) of these cells. Additionally, a greater (P < 0.05) proportion of small CSA myofibers was observed in broilers with severe WB. These results provide evidence that myofiber CSA, as well as the heterogeneity and mitotic activity of myogenic stem cell populations were altered in the presence of WB.

Effect of vitamin D, zilpaterol hydrochloride supplementation, and postmortem aging on shear force measurements of three muscles in finishing beef steers.

Vitamin D (D3) supplementation may be used to increase tenderness in beef from cattle fed zilpaterol hydrochloride (ZH). The study was arranged as a 2 × 2 factorial with fixed effects of ZH (no ZH or ZH fed at 8.3 mg/kg DM for 20 d with a 3-d withdrawal) and D3 (no D3 or 500,000 IU D3·steer·d for 10 d prior to harvest). Cattle ( = 466) were harvested in 2 blocks on the basis of BW with subsequent collection of carcass data. Full loins and inside rounds ( = 144 of each subprimal) were collected for fabrication of 5 steaks from the longissimus lumborum (LL), gluteus medius (GM), and semimembranosus (SM), which were aged for 7, 14, 21, 28, or 35 d. Warner-Bratzler shear force (WBSF) was used to evaluate mechanical tenderness of LL, GM, and SM steaks at all aging periods. Slice shear force (SSF) analysis was conducted on only 14- and 21-d LL steaks. No interactions ( > 0.05) between ZH and D3 occurred throughout the entire study. Supplementing ZH resulted in increased HCW ( < 0.01), larger LM area ( < 0.01), and improved calculated yield grades ( < 0.01) with decreases in fat thickness ( = 0.02) and marbling scores ( = 0.05). Supplementation with D3 increased calculated yield grade ( < 0.01) and decreased ( = 0.01) rib eye area. Feeding ZH increased ( ≤ 0.05) WBSF of LL steaks at each postmortem age interval, whereas D3 had no effect ( > 0.05) on WBSF or SSF of LL steaks. Like for WBSF, ZH supplementation increased SSF values at 14 and 21 d postmortem ( < 0.01) compared with those for non-ZH steaks. There was an interaction between ZH and postmortem age ( < 0.01) for WBSF of LL steaks. At 7 d LL steaks from ZH steers sheared over 0.6 kg greater than non-ZH steaks; however, by 21 d this difference was reduced to an average of 0.2 kg. Differences in distribution between LL steaks below 3.0 kg from non-ZH and ZH-fed cattle were also notable ( ≤ 0.05) through 21 d of aging. At 35 d postmortem a high proportion of LL steaks (68.5%) from ZH-fed steers required less than 3.0 kg to shear. Supplementation with ZH and D3 had no impact ( > 0.05) on WBSF values of GM steaks. Feeding ZH did not alter WBSF of SM steaks, but at 28 d D3 increased ( = 0.04) WBSF values. Shear force in ZH steaks was not effectively reduced by feeding D3 for 10 d to steers prior to harvest. Aging, however, was an effective method of reducing initially greater shear force values in LL steaks and, to a lesser degree, GM steaks from ZH-fed cattle.

Effect of rate of weight gain of steers during the stocker phase. IV. Rumen fermentation characteristics and expression of genes involved in substrate utilization for fatty acid synthesis in adipose tissues of growing-finishing beef cattle.

The objective of this study was to determine the impact of stocker production systems differing in growth rate on rumen fermentation characteristics and utilization of substrates for fatty acid synthesis in intramuscular (IM), subcutaneous (SC), and perirenal (PR) adipose tissues. Angus steers were assigned to 4 stocker cattle production systems in 2 consecutive years: 1) 1.0 kg/d of 40% CP cottonseed meal­based supplement while grazing dormant native range (CON), 2) ground corn/soybean meal­based supplement while grazing dormant native range fed at 1% of BW (CORN), 3) grazing wheat pasture at a high stocking rate to achieve a low rate of BW gain (LGWP), and 4) grazing wheat pasture at a low stocking rate for a high rate of BW gain (HGWP). Eight ruminally cannulated steers were used to determine rumen fermentation characteristics. Steers were harvested during the stocker phase at similar age (different carcass weight) in Exp. 1 (3 steers/treatment) or at similar carcass weight in Exp. 2 (4 steers/treatment). Adipose tissues were analyzed for mRNA expression of genes involved in glucose (solute carrier family 2, member 4 [GLUT4], glucose-6-phosphate dehydrogenase [G6PDH], phosphofructokinase, muscle [PFKM], and pyruvate kinase 2, muscle [PK2]), lactate (lactate dehydrogenase B [LDHB]), and acetate (acetyl-CoA synthetase, cytosol [ACSS2]) utilization for fatty acid synthesis. The acetate:propionate ratio was least (P < 0.05) for HGWP steers, intermediate for CORN and LGWP steers, and greatest for CON steers. At similar age, LGWP and HGWP steers tended (F-test; P < 0.15) to have greater (P < 0.10) G6PDH and ACSS2 mRNA expression than CON and CORN steers in SC and PR but not IM adipose tissue. Expression of PFKM and PK2 mRNA tended (F-test; P < 0.15) to be greater (P < 0.10) in HGWP than CON and LGWP steers in IM but not SC or PR adipose tissue. At similar HCW, expression of GLUT4 and G6PDH mRNA were greater (P < 0.10) in SC adipose tissue of LGWP and HGWP steers compared with CON and CORN steers but not in IM and PR adipose tissue. Expression of LDHB mRNA was lesser (P < 0.10) in SC adipose tissue but greater (P < 0.10) in PR adipose tissue of LGWP and HGWP steers compared with CON and CORN steers. These results indicate a shift toward glucose utilization in SC adipose tissue but a shift towards lactate utilization in PR adipose tissue. These results suggest that diet and changes in VFA profile can influence substrates utilized for fatty acid synthesis, but diet has a greater effect in SC than IM adipose tissue.

Effect of vitamin D status improvement with 25-hydroxycholecalciferol on skeletal muscle growth characteristics and satellite cell activity in broiler chickens.

Skeletal muscle satellite cells (SC) play a critical role in the hypertrophic growth of postnatal muscle. Increases in breast meat yield have been consistently observed in broiler chickens fed 25-hydroxycholecalciferol (25OHD3), but it is unclear whether this effect is mediated by SC. Thus, our objective was to determine the effect of vitamin D status improvement by replacing the majority of dietary vitamin D3 (D3) with 25OHD3 on SC activity and muscle growth characteristics in the pectoralis major (PM) and the biceps femoris (BF) muscles. Day-old, male Ross 708 broiler chickens (n = 150) were fed 1 of 2 corn and soybean meal-based diets for 49 d. The control diet (CTL) contained 5,000 IU D3 per kg of diet and the experimental diet (25OHD3) contained 2,240 IU D3 per kg of diet + 2,760 IU 25OHD3 per kg of diet. Ten birds per treatment were harvested every 7 d. Two hours before harvest, birds were injected intraperitoneally with 5'-bromo-2'deoxyuridine (BrdU) to label mitotically active cells. Blood was collected from each bird at harvest to measure circulating concentrations of 25OHD3, a marker of vitamin D status. The PM and BF muscles were weighed and processed for cryohistological determination of skeletal muscle fiber cross-sectional area, enumeration of Myf-5+ and Pax7+ SC, and mitotically active (BrdU+) SC using immunofluorescence microscopy. Circulating 25OHD3 concentrations were greater in 25OHD3-fed birds on d 7, 14, 21, 28, 35, 42, and 49 when compared with CTL (P < 0.001). Growth performance and feed efficiency did not differ among dietary treatments (P > 0.10). Improved vitamin D status as a result of feeding 25OHD3 increased the number of mitotically active (Pax7+;BrdU+) SC (P = 0.01) and tended to increase the density of Pax7+ SC (P = 0.07) in the PM muscles of broilers on d 21 and 35, respectively. Broiler chickens fed 25OHD3 also tended to have greater Myf-5+ SC density (P = 0.09) on d 14, greater total nuclear density (P = 0.05) on d 28, and a greater muscle fiber cross-sectional area (P = 0.09) on d 49 in their PM muscles compared with CTL birds. Collectively, these results suggest that improvement of vitamin D status by replacing the majority of D3 in the diet with 25OHD3 can stimulate SC activity in the predominantly fast-twitch PM muscle and provide evidence toward understanding the mechanism behind previously observed increases in breast meat yield in 25OHD3-fed commercial broiler chickens.

MRI of CNS fungal infections: review of aspergillosis to histoplasmosis and everything in between.

Fungal infections of the central nervous system (CNS) represent a wide spectrum of diseases with some common magnetic resonance imaging (MRI) features. Risk factors include immunocompromise of any cause and living in endemic areas. CNS infection occurs through hematogenous spread, cerebrospinal fluid seeding, or direct extension. MRI features include heterogeneous or ring reduced diffusion and weak ring enhancement. Angioinvasive aspergillosis is characterized by multifocal hemorrhagic lesions with reduced diffusion. Cryptococcosis results in gelatinous pseudocyst formation in the basal ganglia. Mucormycosis is characterized by frontal lobe lesions with markedly reduced diffusion. Candidiasis is usually manifest by numerous microabscesses of less than 3 mm occurring at the corticomedullary junction, basal ganglia, or cerebellum. Coccidioidomycosis often results in meningitis with contrast enhancement of the basal cisterns. Blastomycosis and histoplasmosis are rare infections with parenchymal abscesses or meningitis. Recognizing the imaging features of CNS infections allows for early, aggressive treatment of these otherwise rapidly fatal infections.

U. S. consumer perceptions of U. S. and Canadian beef quality grades.

A U.S. consumer (n = 642) study (Baltimore, MD; Phoenix, AZ; and Lubbock, TX) was conducted to compare consumer sensory scores of U.S. beef (83 USDA Choice [Choice] and 96 USDA Select [Select]) and Canadian beef (77 AAA and 82 AA) strip loins. Strip loins (n = 338) were obtained from beef processors in Canada and the United States and were wet aged until 21 d postmortem at 2°C. Marbling scores were assigned at 21 d and loins were paired according to quality grades and marbling score. Strip loins were fabricated into 2.54-cm thick steaks; steaks were vacuum packaged and frozen until further evaluations. Proximate analysis was performed to compare fat, moisture, and protein. Choice and Canadian AAA had similar marbling scores and intramuscular fat. Both Choice and Canadian AAA had greater (P < 0.05) marbling scores and intramuscular fat than Canadian AA, but Select strip loins had intermediate values that were not different from any of the other grades (P > 0.05). Consumers' opinions did not differ when comparing equivalent grades (Choice with Canadian AAA and Select with Canadian AA), but they rated Choice and Canadian AAA more palatable than Select and Canadian AA for all sensory attributes (P < 0.05). Regarding percentage of acceptability and likelihood to buy score, consumers indicated a preference and greater probability to buy (P = 0.001 and P = 0.004, respectively) strip loin steaks from higher quality grade carcasses (Choice and Canadian AAA) than lower quality grade carcasses (Select and Canada AA). Additionally, consumers gave their opinion of Canadian beef, where its quality and safety were rated as "good" to "excellent" for both attributes (76.72% and 88.36%, respectively; P < 0.05), feeling confident in beef that is imported from Canada. In the same way, consumers indicated that country-of-origin labeling was a minimal factor influencing their beef steak purchasing decisions. Results from this consumer study indicated U.S. consumers could not differentiate between U.S. and Canadian beef within comparable quality grades; however, strip loin steaks from higher quality grades were more palatable than lower quality grades according to consumer scores for eating quality traits.

Effect of rate of weight gain of steers during the stocker phase. III. Gene expression of adipose tissues and skeletal muscle in growing-finishing beef cattle.

The objective of this study was to determine the impact of stocker production systems differing in growth rate on differential adipogenic and lipogenic gene expression of intramuscular (IM), subcutaneous (SC), and perirenal (PR) adipose tissues. Angus steers were assigned to 4 stocker cattle production systems in 2 consecutive years: 1) cottonseed meal-based supplement while grazing dormant native range (CON), 2) ground corn/soybean meal-based supplement while grazing dormant native range (CORN), 3) grazing wheat pasture at a high stocking rate for a low rate of BW gain (LGWP), and 4) grazing wheat pasture at a low stocking rate for a high rate of BW gain (HGWP). Steers were harvested during the stocker phase at similar age (different carcass weight) in Exp. 1 (3 steers/treatment) or at similar carcass weight in Exp. 2 (4 steers/treatment). Adipose tissues were analyzed for mRNA expression of adipogenic (peroxisome proliferator activated receptor γ [PPARγ], sterol regulatory element binding factor 1 [SREBF1], CAATT/enhancer binding protein ß, and delta-like homolog 1) and lipogenic (glycerol-3-phosphate dehydrogenase [GPDH], fatty acid synthase [FASN], and diacylglycerol acyltransferase 2 [DGAT2]) genes. Multivariate analysis was used to evaluate the expression of adipogenic or lipogenic genes collectively. There was not a treatment × adipose tissue interaction (F-test, P > 0.15) when steers were harvested at similar age, but a treatment × adipose tissue interaction (F-test, P < 0.05) was evident when steers were harvested at similar carcass weight. At similar carcass weight, treatment had no effect (P > 0.10) on the canonical variate of adipogenic or lipogenic mRNA expression in IM adipose tissue, but faster rates of gain of LGWP and HGWP steers increased (P < 0.10) the canonical variate of adipogenic and lipogenic mRNA expression in SC and PR adipose tissue compared with CON and CORN steers. Strong positive correlations (P < 0.05) of PPARγ, SREBF1, GPDH, FASN, and DGAT2 mRNA expression with the canonical variate indicate that these genes strongly influenced differences between treatments and adipose tissues. These results suggest that contrary to our hypothesis rate of gain has little influence on differentiation and lipid synthesis of IM adipose tissue at similar carcass weight but faster rates of gain increase differentiation and lipid synthesis of SC and PR adipose tissue even at similar carcass weight.

Triennial Growth Symposium--A role for vitamin D in skeletal muscle development and growth.

Although well known for its role in bone development and mineral homeostasis, there is emerging evidence that vitamin D is capable of functioning as a regulator of skeletal muscle development and hypertrophic growth. This review will focus on the relatively limited body of evidence regarding the impact of vitamin D on prenatal development and postnatal growth of skeletal muscle in meat animal species. Recent evidence indicating that improvement of maternal vitamin D status through dietary 25-hydroxycholecalciferol supplementation can positively affect fetal skeletal muscle fiber number and myoblast activity in swine as well as work demonstrating that posthatch vitamin D status enhancement stimulates a satellite cell-mediated skeletal muscle hypertrophy response in broiler chickens is discussed. The relative lack of information regarding how and when to best supply dietary vitamin D to promote optimal prenatal development and postnatal growth of skeletal muscle provides an exciting field of research. Expansion of knowledge in this area will ultimately improve our ability to efficiently and effectively produce the livestock required to meet the increasing worldwide demand for meat products.

Improvement of maternal vitamin D status with 25-hydroxycholecalciferol positively impacts porcine fetal skeletal muscle development and myoblast activity.

There is little information available regarding the influence of maternal vitamin D status on fetal skeletal muscle development. Therefore, we investigated the effect of improved vitamin D status resulting from 25-hydroxycholecalciferol (25OHD3) supplementation of dams on fetal skeletal muscle developmental characteristics and myoblast activity using Camborough 22 gilts (n = 40) randomly assigned to 1 of 2 corn-soybean meal-based diets. The control diet (CTL) contained 2,500 IU cholecalciferol (D3)/kg diet, whereas the experimental diet contained 500 IU D3/kg diet plus 50 µg 25OHD3/kg diet. Gilts were fed 2.7 kg of their assigned diet once daily beginning 43 d before breeding through d 90 of gestation. On gestational d 90 (± 1), fetal LM and semitendinosus muscle samples were collected for analysis of developmental characteristics and myoblast activity, respectively. No treatment difference was observed in fetal LM cross-sectional area (P = 0.25). Fetuses from 25OHD3-supplemented gilts had more LM fibers (P = 0.04) that tended to be smaller in cross-sectional area compared with CTL fetuses (P = 0.11). A numerical increase in the total number of Pax7+ myoblasts was also observed in fetuses from 25OHD3-supplemented gilts (P = 0.12). Myoblasts derived from the muscles of fetuses from 25OHD3-fed dams displayed an extended proliferative phase in culture compared with those from fetuses of dams fed only D3 (P < 0.0001). The combination of additional muscle fibers and Pax7+ myoblasts with prolonged proliferative capacity could enhance the postnatal skeletal muscle growth potential of fetuses from 25OHD3-supplemented gilts. These data highlight the importance of maternal vitamin D status on the development of fetal skeletal muscle.

Effect of rate of body weight gain in steers during the stocker phase. I. Growth, partitioning of fat among depots, and carcass characteristics of growing-finishing beef cattle.

Two experiments were conducted to examine the effect of growth rate to similar age or BW on fat deposition in stocker cattle grazing dormant native range (DNR) or winter wheat pasture (WP). In each experiment, fall-weaned Angus steers were randomly allotted to 1 of 4 stocker production programs: 1) control, 1.02 kg/d of a 40% CP cottonseed meal-based supplement during grazing of DNR (CON); 2) corn/soybean meal-based supplement fed at 1% of BW during grazing of DNR (CORN); 3) grazing WP at a high stocking rate to achieve a low rate of BW gain (LGWP); and 4) grazing WP at a low stocking rate to achieve a high rate of BW gain (HGWP). In Exp. 1, a subset of steers (3 steers per treatment) was harvested after winter grazing (138 d) at similar age. The remaining WP steers were transitioned into the finishing phase, whereas DNR steers were allowed to graze the same native range pastures for another 115 d without supplementation before entering the feedyard. In Exp. 2, steers grazed their respective pastures until each treatment reached an estimated HCW of 200 kg (262, 180, 142, and 74 d, respectively, for the CON, CORN, LGWP, and HGWP treatments), at which time a subset of steers (4 steers per treatment) were selected for intermediate harvest before finishing. In both experiments, the remaining steers were fed a finishing diet to a common 12th-rib fat thickness of 1.27 cm. In Exp. 1, winter grazing ADG was 0.19, 0.52, 0.68, and 1.37 ± 0.03 kg/d; and in Exp. 2, winter/summer grazing ADG was 0.46, 0.61, 0.83, and 1.29 ± 0.02 kg/d, respectively for CON, CORN, LGWP, and HGWP treatments. At intermediate harvest in Exp. 1, HGWP steers had greater (P < 0.01) 12th-rib fat thickness and marbling scores, compared with the other treatments. However, in Exp. 2, LGWP steers had greater (P < 0.01) marbling scores compared with HGWP steers, which were greater than DNR steers. At final harvest in Exp. 1, LGWP steers had greater (P < 0.01) 12th-rib fat thickness and smaller LM area, compared with the other treatments; however, there were no differences (P = 0.99) in final marbling scores. In Exp. 2, CON steers had lower (P < 0.05) 12th-rib fat thickness and tended (P = 0.10) to have greater marbling scores, compared with the other treatments. These data suggest that changes in the partitioning of fat among depots during the stocker phase may not be reflected after finishing when steers are fed to a common 12th-rib fat thickness.

Storage length, storage temperature, and lean formulation influence the shelf-life and stability of traditionally packaged ground beef.

The effect of storage length and temperature on the shelf life of three ground beef formulations (lean:fat: 73:27, 81:19 and 91:9) was investigated. Coarsely ground beef was stored at -1.7 or 2.3°C for up to 28d. Traditional overwrap packages were produced every 7d prior to retail display for 24h. Lipid oxidation (TBARS), subjective color, instrumental color, and aerobic bacteria were evaluated after 0 and 24h of display. Formulation influenced initial L* and subjective color values (P<0.05). Storage temperature did not affect initial color, but product stored at 2.3°C was more discolored after 24h (P<0.05). Aerobic bacteria increased as storage d and temperature increased (P<0.05). Initial TBARS increased through d 21, but were lower after 28d. Overall, initial characteristics depended on formulation; however, ground beef shelf-life and stability were largely influenced by storage length and storage temperature.

Effect of rate of body weight gain of steers during the stocker phase. II. Visceral organ mass and body composition of growing-finishing beef cattle.

Two experiments were conducted to examine the effect of rate of BW gain during the stocker phase on visceral organ mass and body composition of growing-finishing cattle that had grazed dormant native range (DNR) or winter wheat pasture (WP). In each experiment, fall-weaned steers were allotted randomly to 1 of these stocker production programs: 1) control, 1.02 kg · steer(-1) · d(-1) of a 40% CP cottonseed meal-based supplement during grazing of DNR (CON); 2) corn/soybean meal-based supplement fed at 1% of BW during grazing of DNR (CORN); 3) grazing WP at a high stocking rate to achieve a reduced rate of BW gain (LGWP); and 4) grazing WP at a low stocking rate to achieve an increased rate of BW gain (HGWP). In Exp. 1, 3 steers per treatment were harvested after winter grazing (138 d). The remaining WP steers were transitioned into a finishing phase and DNR steers were allowed to graze the same pastures for another 115 d before entering a feedyard. In Exp. 2, steers grazed respective pastures until each treatment reached an estimated HCW of 200 kg (262, 180, 142, and 74 d, respectively, for CON, CORN, LGWP, and HGWP treatments), at which time 4 steers per treatment were randomly selected for intermediate harvest before finishing. At the end of the finishing period, 4 additional steers from each treatment were randomly selected for final carcass measurements. All steers were fed to a common 12th rib fat thickness of 1.27 cm. After winter grazing in Exp. 1, HGWP steers had the greatest (P < 0.01) mesenteric/omental fat, total viscera, total splanchnic tissue mass, and carcass and empty body fat, compared with the other treatments. In Exp. 2 at intermediate harvest, WP steers had greater (P < 0.03) mesenteric/omental fat, total viscera, and total splanchnic tissue mass, compared with CORN steers, with CON steers being intermediate. Also, the WP steers had greater (P < 0.02) carcass and empty body fat, compared with CORN steers, with CON steers being intermediate. At final harvest in Exp. 2, LGWP steers had the least total viscera and total splanchnic tissue mass, compared with the other treatments. However, there were no differences (P > 0.53) among treatments for carcass or empty body fat. Stocker systems using WP or DNR result in cattle with differences in body fat and visceral organ mass before finishing; this may influence feedlot efficiency, even though there were no differences in body fat and visceral organ mass at the end of the finishing period.

Effects of postmortem calcium chloride injection on meat palatability traits of strip loin steaks from cattle supplemented with or without zilpaterol hydrochloride.

An experiment was conducted to determine the effects of zilpaterol hydrochloride mM supplementation (ZH; 8.3 mg/kg on a DM basis for 20 d) and calcium chloride injection [CaCl(2), 200 at 5% (wt/wt) at 72 h postmortem] on palatability traits of beef (Bos taurus) strip loin steaks. Select (USDA) strip loins were obtained from control (no ZH = 19) and ZH-supplemented carcasses (n = 20). Right and left sides were selected alternatively to serve as a control (no INJ) or CaCl(2)-injected (INJ) and stored at 4°C. Before injecting the subprimals (72 h postmortem), 2 steaks were cut for proximate, sarcomere length, and myofibrillar fragmentation index (MFI) analyses. At 7 d postmortem each strip loin was portioned into steaks, vacuum packaged, and aged for the appropriate period for Warner-Bratzler shear force (WBSF; 7, 14, 21, and 28 d postmortem), trained sensory analysis (14 and 21 d postmortem), purge loss (7 d), and MFI (3, 7, 14, 21, and 28 d postmortem). Results indicated steaks from both ZH supplementation and INJ had reduced WBSF values as days of postmortem aging increased. The WBSF values of ZH steaks were greater (P < 0.05) than no ZH steaks at each postmortem aging period. The INJ steaks had lower WBSF values (P < 0.05) than non-injected steaks. A greater percentage (91 vs. 71%) of steaks had WBSF values < 4.6 kg from steers with no ZH supplementation at 7 d postmortem, but the percentage did not differ (P > 0.05) due to ZH at 14, 21, or 28 d or due to INJ at any aging period. Trained panelists rated tenderness less in ZH steaks than steaks with no ZH at 14 d and 21 d. However, INJ improved (P < 0.05) the tenderness ratings and flavor intensity of the trained panelists, compared with their non-injected cohorts at 21 d. Zilpaterol hydrochloride supplementation reduced (P < 0.05) MFI values, but INJ resulted in greater (P < 0.05) MFI values compared with no INJ. Subprimals from ZH and INJ showed greater purge loss (P < 0.05). Although no interactions were found with ZH and CaCl(2), injecting USDA Select strip loins from ZH-fed cattle can help reduce the normal WBSF variation as it does in steaks from non-ZH-fed cattle.