Factors associated with student grades in Animal Physiology I

Students and faculty alike would like to know what factors are related to success in college courses. The purpose of this study was to evaluate factors that relate to a student’s success in Animal Physiology I (Phys I), an upper-level animal science course at the University of Arkansas. Student data were confidentially collected and coded. Data collected were student high school grade point average (HSGPA); composite ACT score; English, reading, math, and science subscores on the ACT; and student grades in English composition I and II, college algebra, chemistry, biology, microbiology, animal physiology II, and reproductive physiology. Prematriculation performance confirmed that students with higher HSGPA and (or) ACT scores had better grades in animal physiology I. However, ACT subscores were not more informative than the ACT composite score. Performance in prerequisite courses (chemistry and biology) was significantly related to student grades in Animal Physiology I. Student grades in related courses indicated the same results, that is, students that do well in high school tend to have better grades in college, including in Animal Physiology I

Effect of a direct-fed microbial (Eubios 1090) in the presence of antibiotics (Carbadox or CTC-Denagard) on post-weaning pig growth performance and immune response

A study was conducted to determine the effects of a probiotic (Eubios 1090), in the presence of two different antibiotics, on performance in nursery pigs. A total of 216 pigs were weaned at an average of 21 d, blocked by initial body weight (BW = 6.79 kg), and distributed into 32 pens of 6 to 7 pigs per pen in an offsite nursery facility. Pens were randomly assigned to 1 of 4 dietary treatments (8 pens per treatment) that were fed throughout post-weaning phase 1 (day (D) 0 to 10), phase 2 (D 10 to 20), and phase 3 (D 20 to 34). Dietary treatments were: 1) Carbadox without Eubios 1090; 2) Chlortetracycline + Tiamulin (CTC-Denagard) without Eubios 1090; 3) Carbadox + Eubios 1090; and 4) CTC-Denagard + Eubios 1090. There was no interaction observed between the two antibiotics and addition of the probiotic. There was a tendency for greater gain to feed ratio (G:F) in phase 2 when nursery pigs received Carbadox compared to CTC-Denagard (P = 0.08), and a tendency for greater average daily feed intake (ADFI) in the overall nursery period when pigs were fed CTCDenagard compared to Carbadox (P = 0.10). Pigs that received the non-Eubios 1090 diets had greater average daily gain (ADG), G:F, and body weight (BW) during phase 2 compared to pigs that received diets containing Eubios 1090 (P = 0.05). In phase 3, pigs receiving the Eubios 1090 diet had increased ADG and G:F (P = 0.05). Between the Carbadox diet and the CTC-Denagard diet, the diet containing CTC-Denagard increased ADFI throughout the 3 phases. In summary, probiotic supplementation demonstrated negative effects in phase 2 and positive effects to growth performance in nursery pigs during the latter part of early post-weaning (phase 3)

Use of endocrine and immune responses as predictors of bull sperm motility

Research has shown that peripheral blood cell populations change in response to an immune challenge, and hormone concentrations directly affect sperm characteristics. The objective of this study was to utilize immune responses and hormone concentrations as biomarkers for yearling bull sperm motility. Seventeen Brahman-influenced bulls (mean age 1.1 ± 0.1 yr; body weight 478 ± 38 kg) were administered an intraperitoneal injection of lipopolysaccharide (Salmonella typhimirium 0.7 µg/kg of body weight). Blood was collected 0, 3, 6, 9, and 24 h after LPS injection then analyzed for differential cell count and endocrine concentrations of prolactin, insulin-like growth factor-1 (IGF), and cortisol. Semen was collected using electroejaculation every month for five months then analyzed for motility and morphology characteristics. Hormone concentrations and immune response had an effect on sperm characteristics. Number of sperm was correlated (r \u3e 0.65; P \u3c 0.01) with the IGF to prolactin ratio. Using stepwise regression analysis, we predicted that number of sperm = 172.43 + 12.8 (IGF:prolactin), r2 = 0.43, and progressive sperm motility = -1469.6 + 1.63 (IGF:cortisol) + 14.41 (average temperature during immune challenge), r2 = 0.43. This study showed that endocrine response to stress and activation of the immune system was associated with subsequent sperm motility characteristics. Our results suggest that endocrine and immune responses may be used as biomarkers for sperm motility. Those biomarkers may be useful in selecting replacement bulls

Effects of tall fescue and lactate dehydrogenase genetic polymorphisms on dairy heifer growth and immune function

Objectives of this project were to evaluate polymorphisms in upstream elements of the lactate dehydrogenase B (LDHB) gene in crossbred dairy heifers (n = 27) and their effects on immune function and heifer growth when grazing endophyte-infected tall fescue. Two cultivars of tall fescue were utilized: Kentucky 31 (KY31), a wild-type endophyte-infected tall fescue, and HiMag 4 (HiMag), a domesticated non-toxic endophyte-infected tall fescue. Crossbred dairy heifers (Holstein × Jersey) were stratified by weight and randomly allotted to forage. The LDHB gene codes for one subunit of lactate dehydrogenase (LDH), an enzyme that catalyzes pyruvate to lactate and back to pyruvate. Forward primer used for amplification was 5’-ACACACCAGCAGCATCTCAG-3’ and reverse primer was 5’- GATAAGGGCTGCACGAAGAC-3’. The amplicon size for this LDHB primer set was 457 base pairs. Sequenced amplicons were aligned with Clustal2W for polymorphism detection and genotype assignment. Heifers that had a heterozygous genotype and grazed HiMag were heavier when compared with other heifer groups. Number of red blood cells and hemoglobin concentrations for heifers grazing KY31 were greater when compared to heifers grazing HiMag. Distribution of white blood cells was affected by LDHB genotype. Two dairy heifer management tools, stockpiled tall fescue and LDHB genotyping, were assessed in this study, both of which impacted heifer growth and immune function as assessed by blood cell differentials

Steer stress response as affected by genotype and transportation

Bovine cytochrome P450 3A28 is responsible for metabolizing ergot alkaloids that cattle ingest when feeding on endophyte-infested tall fescue grass. The objective of this research was to determine associations among genotype, transportation, and stress responses. Angus crossbred steers (n = 47) were genotyped (CC, CG, or GG) for a single-nucleotide polymorphism (C994G) in cytochrome P450 3A28. Genotypes were determined by polymerase chain reaction (PCR) amplification followed by restriction enzyme (Alu1) digestion. Steers were backgrounded on a mixedcultivar tall fescue pasture. Following the stocker phase, steers were transported to the feedlot for finishing. Stress responses were determined 27 h prior to, and 6 and 20 h after transport. Plasma concentrations of prolactin and cortisol, and white blood cell expression of prolactin, cytochrome P450, tumor necrosis factor-alpha, and short form prolactin receptor were our indicators of stress. Both time and genotypic effects were determined. Time (P \u3c 0.05) relative to transportation was associated with expression of all four genes tested. In addition, plasma concentrations of cortisol and prolactin, as well as their ratio were affected (P \u3c 0.05) by time. In contrast, neither genotype nor the interaction between genotype and time affected (P \u3e 0.1) our stress indicators. In previous studies, C994G genotype has been associated with cattle productivity; however, those effects were not observed in this study

Aerobic stability of heat and orchardgrass round-bale silage

In Arkansas, silage is typically stored as balage in long rows of round bales wrapped in plastic film. It is important to evaluate the aerobic stability of this fermented forage when it is exposed to air, especially during the winter months when most of it is fed to livestock or sold as a cash crop. Two types of forage, orchardgrass (Dactylis glomerata) and wheat (Triticum aestivum), were harvested in May 2002 and stored as balage. Twenty-one bales of each balage type were unwrapped and exposed to air on 10 Dec. 2002 for 0, 2, 4, 8, 16, 24, or 32 d to evaluate aerobic stability. For both orchardgrass and wheat balage, final bale weight, dry matter (DM) content, and pH were not affected (P \u3e 0.05) by exposure time. Across both balage types, DM recoveries were ≥97% for all bales, indicating that both types of balage were very stable when exposed to air. Concentrations of neutral detergent fiber (NDF) and 48-h ruminal in situ digestibility were not affected (P \u3e 0.05) by exposure time for either balage type. Concentrations of N were greater (P = 0.045) for orchardgrass balage exposed to air for 16 d or longer compared to balage sampled at exposure (d 0), but this response was not observed (P \u3e 0.05) for wheat balage. These results suggest that the balage evaluated in this trial was very stable after exposure to air for up to 32 d. This should allow for considerable flexibility with respect to feeding, transport, and marketing of balage during winter months without significant aerobic deterioration

Cost-benefit Analysis of a Genetic Marker on Cow-calf Operations Differentiated by Pasture and Breed

Genetic sequencing in beef cattle (Bos taurus L.) is expected to aid producers with selecting breeding stock. Using data from experimental trials conducted with Angus, Brahman, and their reciprocal cross, the single nucleotide polymorphism (SNP) P450 C994G marker expression was investigated for use in selecting genetics suited to grazing endophyte-infected tall fescue (Festuca arundinacea Schreb. L.) compared to bermudagrass (Cynodon dactylon L.) pasture. The study is unique in the sense that actual cow-calf breeding failure rates (open cows were not culled) were tracked from 1991 to 1997 on herds that were bred to calf in spring and were either exposed to fungal endophyte-infected (Acremonium coenophialum L.) tall fescue grazing and hay or not. The study used the Forage and Cattle Analysis and Planning (FORCAP) decision support software to assess economic performance driven by birth weight, weaning weight, and breeding failure rate differences across treatment. Results suggest that for reciprocal cross herds primarily grazing bermudagrass pastures, the P450 C994C genotype (CC) was most favorable; whereas, the P450 G994C genotype (GC) was more profitable with tall fescue. Adding genetic market information when selecting a production strategy led to approximately $15/head in added profitability. In comparison to the prorated cost of$2.40/head over the life of a dam, the collection, interpretation, and management of genetic information under the conditions observed in this study may be worthwhile

The possible enzymatic differences between cattle and sheep in their response to ergot alkaloids

Ergotamine is an ergot alkaloid associated with fescue toxicosis of livestock who have grazed endophyte-infected fescue. High performance liquid chromatography (HPLC) was used to detect individual or species-specific differences in the metabolism of ergotamine by liver cytochrome P450 of sheep and cattle. Livers were collected from four steers and two sheep. The diet of the steers used in this study consisted of two being fed a grain diet, one steer grazing endophyte-infected fescue, and the final steer grazing endophyte-free fescue. The two lambs were both fed a grain diet. Livers were prepared and examined for the disappearance of ergotamine and its isomer by HPLC analysis. Liver microsomes from cattle appeared to metabolize ergotamine to a greater degree than those from sheep. There were no apparent differences in the metabolism of ergotamine when comparing cattle that grazed endophyte-infected fescue to cattle that grazed endophyte-free fescue. Therefore, diet had no effect on the metabolism rate of ergotamine. This work provides insight into the possible genetic differences between speciesspecific and individual animals. Further study of such differences should improve breeding programs and produce animals that can more effectively tolerate fescue toxins