Translational Animal Science最新文献

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.

In U.S. breeding herds, data collection is widespread but often fragmented across systems. While producers rely on performance summaries, integration of these data to improve productivity remains underutilized. This study evaluated sow-level factors associated with sow efficiency, defined as weaning-to-estrus interval (WEI), percentage of sows bred within 7 days post-weaning, subsequent farrowing success, and total piglets born. Data were sourced from six lactation trials on a commercial sow farm, with sows of the same genetics (PIC line 1050), housing, and free of Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) and Porcine Epidemic Diarrhea Virus (PEDV). The dataset contained 4,300 observations, including reproductive performance, daily feed intake, sow and litter weights. Generalized linear regression models were constructed with 23 variables; trial was included as a random effect, and model selection performed through manual stepwise forward selection based on biological plausibility. Pairwise comparisons were made using t-tests with the Tukey-Kramer adjustment at P <0.05 significance. Parity (P < 0.001), nursed piglets (P = 0.01), and average daily feed intake (ADFI0 in the first three days (P = 0.01) were associated with WEI. Sows nursing ≥15 piglets had a 1.3-day increase in WEI (P = 0.01), while ADFI <4.5kgs (10lbs) for the first three days was associated with 1-day increase in WEI (P <0.001). Factors associated with breeding within 7 days included parity (P = 0.05), first-week ADFI (P = 0.01), and nursed piglets (P = 0.009). Subsequent farrowing success was associated with prior litter size (P = 0.02), stillbirth rate (P = 0.01), first-week ADFI (P = 0.01), nursed piglets (P = 0.02), and body weight change (P = 0.01). Sows with ≥1 stillborn piglet had a 7% lower farrowing probability (P = 0.01), and those nursing >15 piglets had a 12% reduction (P = 0.02) in farrowing success. Factors associated with subsequent total born included parity (P < 0.001), previous litter size (P = 0.01), piglet birth weight (P = 0.01), caliper change (P = 0.04), stillbirth rate (P 0.01), and the interaction between body weight change and litter wean weight (P = 0.002). Sows with average litter birth weights <1 kg (2.4lbs) produced two more piglets than those >1.5kgs (3.5lbs). Stillbirth rates >5% reduced subsequent litter size by 2 piglets (P <0.05), and caliper gains >1 unit added 2 piglets compared to sows losing a unit of caliper (P  0.05). Overall, early lactation feed intake, litter size, and body condition were associated with reproductive outcomes. Low early lactation-first week- feed intake and high nursing burden extended WEI, delayed rebreeding, and reduced farrowing success, providing evidence-based targets to improve sow productivity.

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.

Components of the pelleting process, such as steam conditioning and feed retention time in the conditioner and die, expose feed to various degrees of heat, moisture, pressure, and shear which changes its physical and chemical characteristics. These changes may influence nutrient digestibility. Therefore, the objective of this experiment was to determine the effect of different pellet die thicknesses on the apparent ileal digestibility (AID) and standardized ileal digestibility (SID) of crude protein (CP) and amino acids (AA) in commercial diets fed to pigs. A total of 12 growing barrows with an initial average body weight of 77.1 ± 3.53 kg were allotted to a triplicated 4 × 4 Latin square design with 4 treatments and 4 periods for a total of 12 replicate pigs per treatment. The dietary treatments consisted of a mash diet and three separate diets that were pelleted using a 1-ton pellet mill equipped with different pellet die length: diameter ratios (L:D) of 6 (26.5- × 4.4-mm), 8 (35.2- × 4.4-mm), and 10 (44.0- × 4.4-mm). The pelleted diets were steam conditioned for 30 s (Wenger twin staff pre-conditioner, Model 150), production rate was kept constant at 708 kg per hour, and conditioning temperature was adjusted to accomplish hot pellet temperature of 85°C. Ileal cannulated pigs were housed individually in pens equipped with a feeder, a drinker, smooth-side walls, and a fully slatted metal floor. For the AID and SID of CP and AA, the diets pelleted using the L:D 8 or L:D 10 pellet dies were greater (P < 0.05) than the mash diet and the diet pelleted using the L:D 6 pellet die, except for Lys, Met, Trp, and Gly. Diets pelleted using an L:D 10 pellet die had increased (P < 0.05) SID Lys compared with the mash control with other treatments being intermediate. Diets pelleted with the L:D 8 or L:D 10 die had increased (P < 0.05) SID of Met compared with the mash diet, whereas there was no difference in SID of Met between the mash control and L:D 6 and L:D 8 pelleted diets. For Trp and Gly, the AID and SID of the diet pelleted using the L:D 8 pellet die were greater (P < 0.05) than if the L:D 6 die was used with the other treatments being intermediate. Results indicate that AA digestibility improvement resulting from pelleting diets depends on pellet die thickness with diets pelleted using an L:D of 8 or 10 having improved AA digestibility for specific AA.

During the preconditioning and feedlot receiving phases of the beef cattle industry, animals undergo a myriad of stressors which may lead to decreased animal performance and immune system function. However, the supplementation of various trace minerals may aid in the mitigation of the negative effects attributed to these stressors. Since many animals experience decreased feed intake during these periods, producers may opt to utilize an injectable trace mineral (ITM) solution to provide prompt supplementation. However, research surrounding cattle health and production effects of such products is variable. Therefore, a meta-analysis further analyzing the effects of ITM solutions was conducted. Studies were collected through independent literature searches, resulting in 16 studies. Data was extracted as treatment means, a value with the ability to calculate standard deviations, p-values, and odds ratios, which were then analyzed within the meta package of R (v. 4.3.2). Overall, the usage of an ITM solution did not affect average daily gain (ADG  P = 0.21) or overall morbidity (P = 0.20) when compared to a saline injection. Additionally, ADG differed between risk classifications (P = 0.03) with the usage of an ITM product increasing ADG by 0.12 kg/d in high-risk cattle (no known management history; P = 0.02) with no effect in low-risk cattle (known management history; P = 0.93) when compared to a saline injection. Furthermore, the administration of an ITM did not affect ADG within the preconditioning (beginning of preconditioning period; P = 0.39) but tended to increase ADG (P = 0.09) by 0.06 kg/day within the feedlot receiving (arrival to feedlot facility) subclasses when compared to a saline injection. Average daily gain did not differ based on the inclusion (P = 0.49) or exclusion (P = 0.37) of additional oral supplementation. Additionally, ADG did not differ (P = 0.15) based on study length, accordingly, ITM usage had no effect in short (≤ 30 days; P = 0.41) or extended (≥ 60 days; P = 0.74) studies, but increased ADG by 0.07 kg/d in moderate (30-60 days; P = 0.04) studies. Lastly, ITM administration did not affect ADG within B. indicus (P = 0.42), but increased ADG (P = 0.05) by 0.03 kg/d within B. taurus cattle and increased ADG (P = 0.21) by 0.09 kg/d within crossbred cattle. In conclusion, ITM administration did not affect overall ADG or morbidity, but may increase ADG within specific production or animal circumstances.

Feeding cattle a total mixed ration (TMR) instead of offering dietary ingredients separately (instead of individually) is generally recommended. Feeding TMR enhances production by reducing feed sorting, decreasing manual labor, and preventing digestive diseases. However, producing TMR requires a specialized mixer that can be expensive and necessitates trained personnel and regular maintenance. Furthermore, some roughages need prior processing before adding to the mixer. Consequently, providing TMR is a methodology hard to adopt by small-sized farm operations. The goal of this study was to evaluate growth performance and carcass characteristics of feedlot cattle offered a TMR or non-mixed ration (NMR; hay and concentrate were provided separately). Angus-Simmental cattle (324.8 ± 29.6 kg) were fed using either a TMR strategy (TMRS; n = 29) or a non-mixed ration strategy (NMRS; concentrate and hay were fed separately; n = 30). Steers were housed individually and fed once a day using individual feed bunks. Irrespective of the treatment, feed offered was subjected to a slicked bunk management. For the NMRS treatment, each bunk was bisected by a wooden plunk bolted to it, for hay and concentrate to be offered in one half each. The ratio hay-to-concentrate (7-to-93) offered was the same between treatment groups. Steers were weighed every 28 d while feed offer and refusals were recorded daily. Post slaughter, yield grade, hot carcass weight, back fat, ribeye area, kidney-pelvic-heart fat, and quality grades (marbling, skeletal maturity, lean maturity) were recorded at the slaughterhouse. Data were analyzed considering the fixed effect of treatment. No differences (P ≥ 0.15) were observed for growth performance or carcass characteristics between treatments. These results likely stem from bunk management practices, allowing adjustments in the amount of feed offered based on the amount remaining in the bunk each day, thus maintaining similar feedstuff ratios across treatments. However, the feed management approaches used in this study might not align with animal group housing, conventionally used in feedlot operations, due to bunk competition and diet selection.