Translational Animal Science最新文献

Nutrient status during pregnancy can impact fetal development and progeny performance in beef females. Many experimental models have examined the impact of reduced nutrient status during late gestation because 75% of fetal growth occurs after 200 days of gestation. More recently, experimental models evaluated the impacts of nutritional status during the first trimester on organ development and progeny performance. The current study examined the variation in ADG during the first trimester (ADG1) in combination with variation in ADG during the last two trimesters (ADG23) of pregnancy and their relationship to progeny performance in beef heifers (n = 2,305) bred by bulls during the breeding season with no form of synchronization of estrus. We further examined the association between early life health events and rate of body weight (BW) gain of heifers during pregnancy. We hypothesized that there would be inherent variation in rate of BW gain during pregnancy among heifers, that this variation would influence progeny performance even when estrus was spread across the breeding season, and that heifers with reduced rates of BW gain during gestation would have an increased number of health events that coincided with the reduced rates of BW gain. Patterns of BW gain were classified as low (L, < median) or high (H, > median) for the first trimester (ADG1) and for the last two trimesters (ADG23), resulting in four patterns of gain for the dams (LL, LH, HL, or HH). Heifers in the LL group produced offspring with the lightest weights at birth and weaning, while heifers in the HH group produced offspring with greatest weights at birth and weaning (P <0.0001). The heifers in the LH and HL group produced offspring with intermediate weights at birth and weaning. There was an interaction of age in months and pattern of rate of gain on the cumulative number of health events until 24 months (P = 0.05). Heifers in the LL and HL group had the greatest number of health events throughout the first 12 months, and then heifers in the HL group had a greater number of health events during gestation. Thus, the largest differences in health events were before the heifers were weaned, not necessarily during gestation. Variation in rates of gain during pregnancy in beef heifers bred by bulls with no form of synchronization can impact progeny performance, and early life health events may have long-term impacts on the performance of the heifer and the performance of her first calf.

A total of 320 barrows (DNA 200 × 400; initially 10.7 ± 0.21 kg) were used in a 21-d growth trial to determine the available P (aP) and true total tract digestible P (TTTD P) release curves for Microtech phytase (VTR Bio-Tech Co, Ltd, Guangdong, China). At ∼21 d of age, pigs were weaned, randomly allocated to pens and fed a common diet for 18 d and then fed a P deficient diet with 0.11% aP and 0.20% standardized total tract digestible (STTD P) for 3 d. On d 21 post-weaning, considered d 0 of the study, pigs were blocked by average pen body weight (BW) and randomly allotted to 1 of 8 dietary treatments with 5 pigs per pen and 8 pens per treatment. Dietary treatments were derived from a single basal diet and phytase, monocalcium phosphate, limestone, and sand were added to create the treatment diets. The basal diet was formulated to contain 0.32% phytate P. Treatments included 3 diets with 0.11%, 0.19% and 0.27% aP (corresponding to STTD P of 0.20%, 0.27% and 0.35%) using monocalcium phosphate and 5 diets with 0.11% aP (0.20% STTD P) and increasing phytase (250, 500, 1000, 1500 and 2000 FTU/kg). On d 14 of the trial, fecal samples were collected from 3 pigs per pen. Samples were analyzed for dry matter (DM), N, P, and TiO₂ for the calculation of apparent total tract digestibility (ATTD) of DM, N and P. At the conclusion of the experiment, 1 pig, closest to the mean weight of each pen, was euthanized for bone analysis. The right fibula, 10th rib, and third metacarpal were collected for the determination of bone density, bone ash weight, and percentage bone ash. Increasing aP and STTD P from inorganic P increased (quadratic, P ≤ 0.050) final BW, average daily gain (ADG), and gain to feed ratio (G:F). Increasing phytase increased (linear, P ≤ 0.012) final BW and average daily feed intake (ADFI) and improved (quadratic, P ≤ 0.042) ADG and G:F. Dry matter digestibility decreased (quadratic, P = 0.043) with increasing aP and STTD P from inorganic P. Phosphorus digestibility increased (linear, P ≤ 0.001) with increasing aP and STTD P from inorganic P and increasing phytase. Bone density, bone ash weight, and percentage bone ash increased (linear, P ≤ 0.004) with increasing aP and STTD P from inorganic P and increasing phytase. The aP release curve based on the average percentage bone ash of the three bones and TTTD P release curve developed for Microtech phytase are: aP release, % = (0.868 × FTU/kg) ÷ (9599.511 + FTU/kg) and TTTD P release, % = (0.00004017 × FTU) + 0.011, respectively.

An experiment was conducted to test the hypothesis that pistachio shell powder can be used as a fiber source in diets for weanling pigs without any negative impacts on pig growth performance. A total of 160 newly weaned pigs (initial body weight = 5.23 ± 0.54 kg) were allotted to 4 dietary treatments using a randomized complete block design with initial body weight being the blocking factor. There were 10 replicate pens per treatment. The control diet contained mainly corn and soybean meal and three additional diets were formulated to contain 5.0, 7.5, or 10.0% pistachio shell powder at the expense of corn. Dietary nutrient and energy concentrations were maintained among diets. Average daily gain (ADG), average daily feed intake (ADFI), and gain to feed ratio (G:F) were calculated for phase 1 (d 1 to 21), phase 2 (d 22 to 42), and for the overall experiment. Blood samples were collected at the end of each phase to analyze for blood characteristics. Fecal scores were also recorded during phase 1. Phase 1 results indicated that ADG, final body weight, and G:F tended to increase as pistachio shell powder increased in the diet (quadratic; P < 0.10), and ADFI increased as pistachio shell powder increased in the diet (quadratic; P < 0.05). In phase 2 and overall, ADG and G:F were not affected by treatment, but ADFI from day 1 to 42 tended to increase as the inclusion of pistachio shell powder increased in the diets (quadratic, P < 0.10). On day 21, total protein in blood increased (quadratic, P < 0.05) with increasing pistachio shell powder in diets. Albumin and gamma-glutamyl transferase also increased (linear, P < 0.05) and chloride (linear, P < 0.10) tended to increase whereas glutamate dehydrogenase and bicarbonate (linear, P < 0.10) tended to decrease as pistachio shell powder increased in diets. On day 42, red blood cell count was reduced by pistachio shell powder (quadratic, P < 0.05) whereas mean corpuscular hemoglobin tended to increase (linear, P < 0.10), blood urea nitrogen increased (quadratic, P < 0.05), chloride tended to increase (quadratic, P < 0.10), and cholesterol increased (linear, P < 0.05) with increasing dietary pistachio shell powder. In conclusion, with the exception of a tendency for increased ADFI, overall growth performance of weanling pigs was not affected by including up to 10% pistachio shell powder in diets for weanling pigs indicating that pistachio shell powder may be added to diets for weanling pigs.

Tenderness and marbling are key carcass quality traits in beef cattle that strongly influence consumer eating satisfaction and repeat purchasing behavior. Because both traits are measured postmortem, they are difficult to incorporate into routine selection programs. Genomic selection therefore provides a practical strategy to improve these traits. This study evaluated the effectiveness of GWAS-informed SNP preselection for predicting Warner-Bratzler shear force (WBSF) and marbling breeding values using reduced marker densities in Brangus cattle. Using a structured population (N = 1066), we conducted a 10-fold cross-validation with SNP subsets ranked by GWAS significance and compared them to 10 random SNP subsets of the same number and full SNP panel. External validation was performed using 338 animals from an independent source. For WBSF, small panels (eg top 50 SNPs) achieved accuracy comparable to the full panel, driven by a strong QTL on chromosome 29 (CAPN1). In contrast, marbling required broader marker coverage for optimal prediction, consistent with a polygenic trait architecture. Across all subset sizes, GWAS-ranked SNPs outperformed random subsets, and in several cases matched full panel accuracy. External validation confirmed the reliability of these results. These results demonstrate that trait-specific genetic architecture strongly influences the marker density required for reliable genomic prediction and highlight the value of GWAS-informed SNP prioritization for optimizing genomic prediction strategies in crossbred cattle.

Mimosine, a non-proteinogenic amino acid found in Leucaena plant, is a toxic compound that induce thyroid disorders. Feeding this legume has been shown to reduce serum triiodothyronine (T₃ ) and thyroxine (T₄ ) levels in cattle. Since these hormones are involved in regulating basal metabolism in mammals, we hypothesized that decreasing levels of these hormones would impact energy metabolism, affecting heat production (HP) and energy requirements for maintenance. Six non-castrated Brangus bulls with an average body weight (BW) of 311 ± 17 kg and 20 ± 2 months of age were randomly distributed in a crossover design 3x6 with repeated measures (two animals per experimental unit). Treatments were levels of inclusion of Leucaena in to the diet: control (CTL, 0%); low level (L₁ , 30%) and high level (L₂ , 60%) (dry matter basis). Each experimental period lasted 34 d with 14 d of dietary adaptation in individual metabolic cages followed by 20 d for measurement of response variables. Thyroid hormones (TH) concentration in blood serum, diet digestibility, energy metabolism and gas exchange were measured. Oxygen consumption (O₂), carbon dioxide (CO₂ ) and methane (CH₄ ) production were measured for 2 consecutive d in fed and fasted bulls in two open-circuit respiration chambers. Mimosine intake was 0, 15.10 and 31.33 g/d, respectively. However, no effect on the concentration of T₃ and T₄ in blood serum was observed (P = 0.72 and P = 0.57, respectively). Similarly, O₂ consumption, CO₂ and CH₄ production were similar among treatments in both fed and fasted states (P = 0.18). The mean net energy requirement for maintenance of Brangus bulls was 407.9 kJ/kg^0.75/d and was not influenced by treatment (P = 0.32). Energy lost in feces (MJ/d and as a proportion of total gross energy intake) was greater in the treatment with high level of Leucaena (P = 0.0005 and P = 0.03, respectively) and had a linear effect in both variables. However metabolizable energy intake (MEI) showed no differences among treatments (P = 0.12). Retained energy (RE) ranged from 3.20 to 5.04 MJ/d with no significant differences observed (P = 0.51). These results indicate that the inclusion of Leucaena at the maintenance level of feeding does not affect the concentration of thyroid hormones or energy metabolism of cattle.

Ketosis and its severe complication in small ruminants, pregnancy toxemia, are major metabolic disorders characterized by hypoglycemia and high blood concentrations of β-hydroxybutyrate (BHBA) resulting from negative energy balance (NEB). Although conventional treatments rely on glucogenic precursors like glycerol and propylene glycol, farmers often turn to lower-cost alternatives, including sugary soft drinks containing high-fructose corn syrup (HFCS) and carbonated water (cWater). In this study, we evaluated the relative contribution of the primary components of Coca-Cola (Coke), used here as a representative and readily accessible energy source, in mitigating NEB in sheep. Twenty-eight Afec-Assaf ewe lambs (N = 28), fasted for 48 h to induce NEB, were randomly assigned to four treatment groups (n = 7): 1 L of either Water, cWater, carbonated HFCS solution (cHFCS), or Coke. Blood samples were collected at 0 and 1, 2, and 3 h post-treatment to measure glucose and BHBA concentrations. Glucose area under the curve (AUC) values were highest in cHFCS (2339.5 ± 628.6 mg/dL × min) and Coke (1778.5 ± 437.6 mg/dL × min), intermediate in cWater (950.8 ± 391.3 mg/dL × min), and lowest in Water (570.0 ± 184.5 mg/dL × min). ANOVA indicated significant treatment effects (P <0.037), with post-hoc analysis showing that cHFCS yielded higher glucose AUC than Water (P <0.05). BHBA AUC also differed significantly among treatments (P <0.018), with greater effects for cHFCS (-4.72 ± 4.55 mM × min) and Coke (-5.59 ± 2.96 mM × min) compared with Water (-20.98 ± 5.1 mM × min) and cWater (-21.02 ± 5.12 mM × min). Pairwise comparisons showed no significant differences between cHFCS and Coke, but indicated a trend (P = 0.08) toward a greater response to cHFCS compared to Water and cWater. Overall, the results identify HFCS as the primary component of soft drinks responsible for improving NEB, suggesting that HFCS could represent a practical and economical energy supplement for on-farm ketosis management.

Angus-cross (216; 292 ± 22 kg) steers were used to understand the implications of growth promoting technologies on measures of cattle growth, serum metabolites, and nitrogen excretion. Steers were blocked by BW into heavy (16 pens) and light (20 pens), with 6 steers per pen. One of four treatments was applied to each pen. Treatments (TRT) consisted of (i) no implant or β-adrenergic agonist (β-AA; CON), (ii) implants (IMP: Synovex Choice: 100 mg trenbolone acetate, 14 mg estradiol benzoate [d 0]; Synovex Plus: 200 mg trenbolone acetate, 28 mg estradiol benzoate [d 69]), (iii) IMP + β3-agonist lubabegron fumarate (LUB: 36 mg/steer daily for 53 d, 4-d withdrawal), (iv) IMP + β1-agonist ractopamine hydrochloride (RAC: 300 mg/steer daily for 31 d). From terminal implant onwards, study days were held consistent to days relative to harvest for each block. Body weights were recorded and blood was collected on 1 steer per pen on days -1, 0, 69, 98, 116, 141, and 172. Serum urea nitrogen (SUN), glucose, insulin, and non-esterified fatty acids (NEFA) were analyzed. Insulin sensitivity and urinary nitrogen excretion was estimated. Carcass data were collected following a 48-h chill. Proc Mixed (SAS) was used to analyze data using treatment and block as fixed effects, serum metabolite data were analyzed as repeated measures (day as repeated). Final body weight, average daily gain, dry matter intake, and gain: feed were greater with the use of growth promoting technologies (P < 0.01). Net return tended to be greater in LUB than RAC and CON, IMP was not different from other treatments (P = 0.07). Hot carcass weight was greatest in LUB, less in IMP and RAC and least in CON (P < 0.01). Marbling was least in LUB with CON and IMP being greatest and RAC being not different from other treatments (P < 0.01). Urinary nitrogen output decreased per unit of carcass adjusted ADG with the use of growth promoting technologies (P < 0.01). Serum urea nitrogen had a TRT × Day effect (P < 0.01) where CON cattle were generally greater than other treatments until d 172, indicating SUN was less in RAC and IMP, and least in LUB during the LUB feeding period. Insulin sensitivity index values were generally lesser in CON compared to all other treatments and increased greatly in LUB during the β-AA feeding period (TRT × Day; P < 0.01). Growth-promoting technologies reduce the beef industry's environmental footprint and enhance carcass value by improving feed efficiency.

Bovine respiratory disease (BRD) is the most frequent and costly disease in U.S. feedlots. Metaphylactic antimicrobial use effectively reduces morbidity and mortality in cattle at high risk of BRD, however, its implementation is challenging when risk classification is unclear, and the cost-benefit is uncertain. This study aimed to collect and analyze input from feedlot managers and veterinarians on the criteria used to administer metaphylaxis on cattle of uncertain, or "medium" BRD risk. Responses from 25 veterinarians consulting for 617 feedlots (80 to 120,000 animal capacity) across 32 states, and 30 managers overseeing feedlots across 12 states (500 to 120,000 animal capacity) were analyzed. Nearly half of veterinarians (48%) expected BRD morbidity of 15% to 20% and mortality of 2% to 3% in cattle at medium-risk, whereas only about 15% of managers shared these same expectations. Manager expectations varied widely, with 55% anticipating morbidity of 5% to 15% and no clear consensus on expected mortality. Veterinarians most frequently identified cattle history (64%), weight (59%), commingling (50%), transportation time (50%), and weather (50%) as the primary criteria for determining the need for metaphylaxis in cattle at medium BRD risk. Managers cited similar factors but most often reported source (45%) and origin (35%) as key considerations, with less frequent mentions of weather (14%) and weight (28%). Before cattle arrived at the feedlot, "market channel" was the most influential factor for considering metaphylaxis use according to both veterinarians (73%) and managers (82%), whereas after cattle arrival, "overall cattle health condition" was the most cited factor (69% of veterinarians and 75% of managers). By contrasting the perspectives of veterinary consultants and feedlot managers, we identified consistencies and discrepancies in their perceptions, information use, and the challenges associated with metaphylaxis decisions for these cattle cohorts. These findings contribute to a better understanding of the information that feedlot professionals use and need to guide metaphylaxis decisions in cattle at uncertain BRD risk, thereby supporting efforts toward antimicrobial stewardship and sustainable beef production.

This study assessed the growth, carcass traits, and rumen morphology of feedlot cattle fed reduced levels of organic trace minerals (OTM) in proteinate forms and Se-yeast, replacing inorganic trace minerals (ITM) sources in combination with exogenous amylase. One hundred and twenty commercial yearling Nellore bulls with an initial body weight (BW) of 349.20 ± 22.90 kg were allocated to 24 pens. The study employed a completely randomized block design with a 2 × 2 factorial treatment arrangement. Factors included ITM or OTM sources/level with or without exogenous amylase (Amaize, Alltech, Maringá, PR, Brazil [0.5 g/kg of dry matter]). The ITM supplement contained Co, Cu, Fe, Mn, and Zn in sulfate form, with Se provided as sodium selenite. The OTM supplement provided Co, Cu, Fe, Mn, and Zn in proteinate form at 50% of the levels supplied by the ITM supplement, while Se, as Se-yeast, was included at the same level as in the ITM supplement. Both supplements also contained Cr as Cr-yeast and I as sodium iodide. Cattle were fed the same diets, except for the inclusion of trace minerals and exogenous amylase. There was no interaction (P ≥ 0.12) between trace mineral and exogenous amylase for any variable evaluated. Cattle fed OTM tended to have higher average daily gain (ADG; P = 0.07) and gain-to-feed (G: F) ratio (P = 0.06) compared to cattle fed ITM. Cattle fed exogenous amylase had greater dry matter intake (DMI), whether measured in kg/d (P = 0.03) or as a percentage of BW (P = 0.02), with no (P ≥0.10) effect on ADG and G: F ratio compared to cattle not fed exogenous amylase. There was no main effect of trace mineral or exogenous amylase inclusion (P ≥ 0.15) on any of the carcass traits evaluated, except for final Biceps femoris fat thickness (P = 0.05), which were higher in cattle fed OTM. Rumenitis score and rumen morphology were also not different (P ≥0.14). Overall, feeding reduced OTM levels did not exert adverse effects on growth, carcass traits, or rumen morphology in feedlot Nellore cattle, while modestly enhancing ADG, G: F ratio, and Biceps femoris fat thickness compared to ITM sources. The exogenous amylase inclusion increased DMI without differences in ADG, G: F ratio, carcass characteristics, or rumen morphology.

With the advances in high-throughput technologies, genomic information is becoming readily available. This has led to whole genome sequences and denser single nucleotide polymorphism (SNP) panels being generated for more individuals. However, the increase in genomic information has shown little benefit in improving the prediction accuracy of genomic estimated breeding values (GEBV). One method to best utilize the increased amount of SNP information is to optimize the selection of informative SNP markers. In this study, genomic prediction of growth traits in two closed beef cattle populations using various prioritization techniques was evaluated. The first population used is Line 1 Hereford. The data consisted of 1192 animals with genotypes and phenotypes. The second population is a composite breed (50% Red Angus, 25% Charolais, 25% Tarentaise) and included of 2776 genotypes and phenotypes. The SNP prioritization methods adopted in this study were based on fixation index (Fst) and GWAS based SNP marker effects. Using a subset of prioritized SNP markers increased the accuracy for all three traits for the Line 1 Hereford population. On the other hand, using a weighted G matrix based on Fst and SNP effects did not increase the accuracy and in some instances decreased. Furthermore, the predication accuracy was higher in Line 1 Hereford which is an inbred population compared to the composite population. The study showed that prediction accuracy of GEBV can be improved with SNP prioritization, however it is population specific, trait specific and model specific. Moreover, this study highlights the importance of population structure in the prediction accuracy of GEBV.