Hair Coat Score Research Articles

Examining the Long-Term Impacts of Ergot Alkaloids on Fetal Heifer Development and Subsequent Growth and Reproductive Performance.

Consumption of toxic endophyte-infected tall fescue results in poor reproductive performance in domestic livestock. In this study, the objective was to evaluate the effects of ergovaline exposure during mid-gestation (days 93 through 188 of gestation) on dam performance, the growing female fetus, and the subsequent growth and reproductive performance of the gestationally-exposed heifer calves. Pregnant Angus and Simmental-Angus cows were blocked by age (2 - 3, 4 - 7, and > 7 y), body weight (BW), and breed; and then randomly assigned to graze either novel (EN; <5% infection rate; n = 27 Year 1, n = 16 Year 2) or toxic endophyte-infected tall fescue (EI; 99% infection rate; n = 27 Year 1, n = 17 Year 2). Weekly BW, body condition scores (BCS), hair coat scores (HCS), hair shedding scores (HSS), and blood samples for progesterone (P4) analysis were collected from mid-April through July of 2017 (Year 1) and 2018 (Year 2). Gestation length, birth weight, placental characteristics, heifer calf growth, onset of puberty, ovarian characteristics, and artificial insemination (AI) pregnancy rates were measured. Data were analyzed using the MIXED procedure of SAS. Cows grazing EI pastures had reduced ADG, reduced BCS, greater HSS, and decreased P4 concentrations compared to cows on EN pasture (P < 0.01). Birth weights were decreased for heifers whose dams were exposed to EI pastures during their second trimester (P < 0.01). Heifer pregnancy rates were not impacted by EI pasture exposure during gestation for either year of the study. However, a treatment by year effect was seen for pregnancy rate for EI exposed heifers in Year 2; EI exposed heifers in Year 2 had increased pregnancy rates at two of the inseminations. Combined, these data reinforce that consumption of toxic endophyte-infected tall fescue during gestation can negatively impact both dam and offspring performance. More studies are needed to evaluate more parameters in an effort to elucidate the possible life-long impacts of ergovaline exposure during gestation.

82 Effects of a red-clover containing mineral on heifer behavior and fertility

Abstract Heat stress reduces reproductive efficiency in beef cattle. Recent evidence suggests that supplementation of red clover can alleviate the physiological impacts of fescue toxicosis which could decrease heat stress. Our objective was to determine the effect of supplementing heifers grazing endophyte-infected tall fescue (E+ TF) with a conventional mineral containing red-clover leaf. We hypothesized that heifers supplemented with the red-clover leaf mineral would have greater conception rates to AI (CRAI) in times of possible heat stress compared with heifers supplemented with conventional mineral. A grazing study was conducted from May – August in 2021, 2022, and 2023. Yearling beef heifers (n = 32, 36, 40 heifers yr-1, respectively) were blocked by body weight, hair coat score and color into 4 grazing blocks that were assigned to 1 of 2 treatments (2 blocks treatment-1): 1. conventional non-medicated loose mineral control (0%-RC), or 2. conventional loose mineral + 20% wt/wt red clover leaf (20%-RC). Mineral treatments were provided in ground, 3-compartment mineral feeders ad libitum. Each grazing block was assigned to four, 0.8- ha. pastures consisting of predominantly E+ TF and were rotationally managed over the course of the study. Each year estrus was synchronized suitable for fixed time AI in May and all heifers resynchronized in June. In addition, each heifer was fitted with an ear-tag sensor (CowManager SensOor, Agis Automatisering BV, Harmelen, the Netherlands) for continuous behavioral monitoring (including high activity and activity). The CRAI were analyzed with the GLIMMIX procedure of SAS using the binomial distribution link logit function (v.9.4., SAS Inst. Inc., Cary, NC). Total daily activity and high activity reported by CowManger during May and June were analyzed by the MIXED procedure with repeated measures of SAS. The CRAI were similar for 20%-RC (67.30 ± 9.80%) and 0%-RC (60.70 ± 9.80%) heifers following the first service of AI (P = 0.51) during a thermoneutral period in May. In contrast, CRAI was greater (P = 0.02) for 20%-RC heifers (48.67 ± 13.47%) than CM (15.10 ± 13.47%) in June when temperatures increased to potential heat stress levels. Overall, conception rate after two rounds of AI for 20%-RC (78.30 ± 9.30%) heifers tended to be greater (P = 0.08) than CM (62.20 ± 9.30 %). While high activity (associated with estrous behavior) reported by CowManager did not differ between treatments (20%-RC: 203.94; 0%-RC: 213.90; SEM: 8.65 min d-1; P = 0.25), normal daily activity of 20%-RC heifers (150.69 ± 10.40 min d-1) tended to be greater (P = 0.06) than CM (126.33 ± 8.65 min d-1). Results of this study suggest supplementing red-clover containing mineral may mitigate negative effects of consuming E+ TF including decreased conception rates during times of heat stress.

Magnitude and persistence of higher estrus-associated temperatures in beef heifers and suckled cows.

Higher estrus-associated temperatures (HEAT) are a hallmark feature in sexually active females. The overarching aim of this study was to characterize the variability, magnitude, and persistence of HEAT in heifers and suckled beef cows as well as identify associated factors when occurring during thermoneutral conditions at the onset of the spring breeding season. In both heifers and cows, estrus was induced using a 7-d controlled internal drug release (CIDR)-PGF2α protocol. Vaginal temperature after prostaglandin F2α administration was recorded every 5min using a Thermochron iButton affixed to a blank CIDR (containing no progesterone). Estrus was defined as when a heifer first stood to be mounted or when a cow had an Estrotect patch score of 3 or 4. Level of HEAT varied among individual animals. When comparing common HEAT variables using a mixed model with date nested within a year, maximum HEAT (39.9 ± 0.1 and 40.0 ± 0.1 °C) and duration (15.5 ± 0.8 and 15.4 ± 0.7) were similar in heifers and cows, respectively. However, the magnitude and persistence of HEAT differed. Total area under the HEAT curve was 117.1 ± 13.5 and 158.7 ± 12.3 for heifers vs cows, respectively (P = 0.0571). Further, 42.9% of heifers and 49% of cows had maximum HEAT ≥ 40 °C which persisted up to 6.5 and 10h, respectively. When ambient conditions were predominantly thermoneutral, temperature humidity index had minimal impact on HEAT (mixed model, repeated measures over time). Toward identifying associated factors with different aspects of HEAT using best fit hierarchical linear regression models, baseline vaginal temperature and baseline duration were the most highly associated independent variables. Follicle size, estradiol and progesterone levels, and other available animal-related variables (e.g., age, weight, hair coat score) explained only a small amount of variation in HEAT. In summary, level of HEAT varies in estrus females even under thermoneutral conditions. Because HEAT can persist for an extended time, direct effects on fertility important components are unavoidable. Whether HEAT is a good or bad component of the periovulatory microenvironment is the basis of ongoing and future studies.

197 Trace Mineral Source Affects Haircoat Characteristics and Shedding in Cats

Abstract Trace minerals have a pivotal role in maintaining skin health and haircoat characteristics in companion animals. The objective of the current study was to evaluate the effects of inorganic versus amino acid complexed sources of trace minerals on feline skin and haircoat characteristics as well as hair growth. A total of 40 cats (age 5 – 12 years; 22 female, 18 male) were used in this 105-d (15-d acclimation; 90-d test period) trial at Summit Ridge Farms (Susquehanna, PA) from January to April 2022. All cats were fed a basal diet that contained sulfate sources of trace minerals formulated to meet AAFCO (2021) recommendations for 15 d before being randomly assigned (blocked by haircoat color, age, sex, and weight) to 1 of 2 treatments. Dietary treatments included sulfate sources (CON; n = 20) and amino acid complexed (Zinpro ProPath, Zinpro Corp. Eden Prairie, MN) sources (ZPM; n = 20) of supplemental trace minerals. Both treatments were formulated to provide equal amounts of supplemental trace minerals (DM basis), differing only in source (100 ppm Zn, 15 ppm Mn, 12 ppm Cu, 80 ppm Fe). On d 15, a side patch was shaved just below the back (3” x 4”) to evaluate hair growth on d 60 and 105 (average of 3 measurements). Additionally, visual haircoat evaluations and shed hair amount were evaluated at d 60 and 105. All research personnel were blinded to treatments. Statistical analyses were completed using GLIMMIX procedure of SAS 9.4 with d 15 as a covariate and cat as the experimental unit. Trace mineral source did not affect body condition score at either time point. There was no treatment or treatment x day interaction for hair length. A trend (p = 0.13) for a 3-way interaction between treatment, sex, and day was detected due to male cats having longer hair at d 105. Shed hair was evaluated by brushing (20 strokes) and weighing collected hair. No overall treatment effect was detected for shed hair; although, a treatment x day interaction (P = 0.02) for shed hair was observed. At d 60, ZPM cats had 23 mg less shed hair compared with CON cats (P = 0.08). Haircoat scores for shine, scale, and overall quality were assessed by a veterinarian. There were no treatment or treatment x day interactions for shine or overall scores. A treatment x day interaction was detected (P = 0.02) for scale (dander). At d 60, ZPM cats had a reduced average scale score compared with CON cats (0.66 vs 1.05, respectively; P = 0.03). Overall, our data suggests trace mineral source may influence shed hair amount and dander production in cats. Further research to evaluate the influence of season and sex is warranted.

14 Mitigation Strategies for Heifer Development on ‘KY-31’ Tall Fescue

Abstract Tall fescue (Schedonorus arundinaceus) is the predominant cool-season perennial forage in the Eastern U.S. However, a symbiotic endophyte reduces performance of animals grazing tall fescue. This results in losses of around $2 billion annually. Due to the vasoconstriction caused by the endophyte, a decrease in conception rates among cows and heifers consuming tall fescue has been observed. With rising input costs, it is necessary to explore alternative mitigation strategies these production losses. The objective of this study was to mitigate the toxic effects of ‘KY 31’ tall fescue by limit-grazing cool-season annuals as an alternative to feed supplementation. In January 2022, 48 heifers [14 months of age; 365.9 ± 11.89 kg body weight (BW)] were randomly assigned to tall fescue only, tall fescue with supplemental feed at 1% of BW, tall fescue with limit grazing of cool-season annuals for 24 h per week, and cool-season annuals only. Four animals grazed in each of three replicated paddocks per treatment. Cool-season annual pasture was a mixture of crimson clover (Trifolium incarnatum), annual ryegrass (Lolium multiflorum), and oat (Avena sativa). Body condition scores (BCS), hair coat scores (HCS), and BW were recorded every 30 d. Forage samples were taken for biomass, nutritive value, and ergovaline concentration every 30 d. On April 1, 2022, heifers were artificially inseminated (AI), and conception rates were determined 45 d after AI. Data were analyzed using the Glimmix procedure of SAS 9.4 (SAS Inst, Cary, NC) with α = 0.05. There were no differences among treatments in HCS at any weigh date (P &amp;gt; 0.05). The BCS for all treatments was less in February than January or March (5.6, 6.1, 6.1, respectively; P &amp;lt; 0.0001), but there were no differences among treatments at any sampling date (P &amp;gt; 0.05). Conception rates were not different among treatments (P &amp;gt; 0.10) but averaged 75, 67, 42, and 50% for the continuous-cool season, limit graze, supplemental feed, and tall fescue treatments, respectively. Crude protein (CP) concentrations for the control and limit grazing fescue treatments were greater than the limit grazing cool-season annual treatment, continuous grazing cool-season annual treatment, and the supplemental feed treatment (13.5, 10.7, 10.4, and 8.9%, respectively, (P &amp;lt; 0.012). Neutral detergent fiber (NDF) and acid detergent fiber (ADF) were different among the supplemental treatment when compared with the limit grazing fescue, limit grazing cool-season annual, control, and continuous cool-season annual (48.2 vs 64.7% NDF and 25.8 vs. 37.0% ADF; P &amp;lt; 0.0361). At this time, the results indicate that limit grazing cool-season annual forages may be an advantageous option to mitigate fescue toxicosis in replacement heifers grazing tall fescue pastures in the spring.

90 Exposure to Endophyte-Infected Tall Fescue Negatively Impacts Pulmonary Arterial Pressure in Beef Cattle

Abstract Fescue toxicosis negatively impacts cattle productivity. Previous data from our laboratory has demonstrated that cattle within a herd respond differently when grazing tall fescue, thus variation within a breed may provide genetic tolerance to the negative effects on performance. Fescue toxicosis results in major impacts on the cardiovascular system, thus it was hypothesized that exposure to ergot alkaloids negatively impacts pulmonary arterial pressure (PAP). The objective of this study was to examine changes in PAP and other production parameters in cattle consuming endophyte-infected tall fescue. Pregnant Angus cows (2 to 4 years; n = 65) were randomly divided to graze either endophyte-infected (EI) or novel endophyte (EN) pastures for4 consecutive weeks starting in April. Weekly measurements were collected to monitor physiological responses to consuming endophyte-infected tall fescue. In addition, PAP was measured every 4 weeks. Data were analyzed using a MIXED procedure of SAS, and statistical significance was determined at P &amp;lt; 0.05 and a tendency at 0.05 &amp;lt; P &amp;lt; 0.10, and evaluated the effects of treatment, age, week, and its interactions on BW, ADG, BCS, HCS, HSS and PAP. Exposure to EI did not affect BW, ADG, or BCS (P &amp;gt;0.05). Whereas, hair coat scores (1-5 scale) were significantly less for cattle consuming EN pastures (2.15 ± 0.05) compared with consuming EI pastures (2.31 ± 0.05; P &amp;lt; 0.05). Additionally, shedding scores (1-5 scale) were reduced in cattle consuming EN pastures (2.3±0.05) compared with consuming EI pastures (2.5±0.05; P&amp;lt; 0.05). There was a significant difference in PAP measurements in cattle exposed to EN pastures (37.16 ± 0.59 mm Hg) compared with EI pastures (31.31 ± 0.56 mm Hg; P &amp;lt; 0.0001). Additionally, PAP scores tended to deviate over the 14-week study between treatment groups (P = 0.0677). As expected, exposure to EI tall fescue resulted in greater HCS and HSS. However, the decrease in PAP in cattle consuming EI fescue was unexpected. Thus, further investigations are needed to examine the interaction between ergot alkaloid exposure on cardiovascular parameters such as PAP to potentially predict genetic differences in beef cattle to identify animals that would have a lower risk of developing fescue toxicosis.

Stocker Steer Gains and Fly Numbers as Impacted by Burn Date and Type of Mineral on Tallgrass Native Range – Year 4

This study aims to evaluate effectiveness of two operational management systems for steer gains and fly control. The first strategy evaluated was pasture burn date of March (MAR) or April (APR). The second management strategy was free-choice mineral with spices (SPICE) or without spices (CON). Eight pastures (n = 281 steers; initial weight 566 lb) were used in a 2 × 2 factorial treatment structure. Steers were weighed individually, randomly assigned to treatment, and grazed for 89 days. Weekly, 33% of steers were photographed to count flies and evaluated for hair coat score. Steers that grazed pastures that were burned in March had a greater average daily gain than those grazing pastures that were burned in April and resulted in nearly 30 pounds more gain per calf during the grazing season. Steers that consumed the mineral that contained the spices/essential oils had a 0.10 pound per day advantage as compared to steers on control mineral. There was an interaction between pasture burn date and mineral type where steers gained the most on March burned pastures (with no difference in mineral type), had the second greatest gains on the April burned pastures with Spice mineral, and had the lowest gains on the April burned pastures with Control mineral. Weather plays a very important role in cattle performance following a complete pasture burn, and in a year with excessive spring moisture and extreme drought beginning in June, a March burn was the better management practice.

Evaluation of Implants, Clover, and Fescue Variety on Stocker Steers – Year 2

Sixty-four growing steers were used in a split-plot experiment, where the whole plot was pasture, and the split-plot was the implant level. Whole plot treatment was a 4 × 2 factorial with four levels of fescue (High Endophyte, Low Endophyte, Novel, or Endophyte Free) and two levels of legume (Legumes or No Legumes). The split-plot included four implant levels (No Implant, Synovex One Grass, Revalor-G, or Ralgro). Data collected were weights, hair coat scores, hair length, rectal temperature (every 28 days), and ultrasound carcass characteristics when steers were coming off grass. Steers on High Endophyte had the lowest average daily gain (ADG) and final weight and smallest loin muscle as compared to steers on all other fescue types. The gain differentiation was observed beginning at day 56 through the end of the study. Overall, ADG was not impacted by the addition of legume. Steers that were implanted with Synovex One Grass had a greater gain, final weight, and lower hair score as compared to non-implanted steers. For many of the other measures, steers implanted with Ralgro or Revalor-G resulted in changes between non-implanted steers and those receiving Synovex One Grass. Steers on high endophyte fescue had greater final weight and ADG than non-implanted steers or those receiving Ralgro, with Synovex One Grass being intermediate. Gains for steers on endophyte free pastures were also impacted by the type of implant where Synovex One Grass steers had greater gains than non-implanted and Revalor-G steers, with Ralgro being intermediate. In this second year of research, the use of low to no endophyte fescue and the addition of implants increased gains.

Stocker Steer Gains and Fly Numbers as Impacted by Burn Date and Type of Mineral on Tallgrass Native Range – Year 3

This study aims to evaluate effectiveness of two operational management systems for steer gains and fly control. The first strategy evaluated was pasture burn date of March (MAR) or April (APR). The second management strategy was free-choice mineral with spices (SPICE) or without spices (CON). Eight pastures (n = 281 steers; initial weight 572 ± 75 lb) were used in a 2 × 2 factorial treatment structure. Steers were weighed individually, randomly assigned to treatment, and grazed for 87 days. Weekly, 33% of steers were photographed to count flies and evaluated for hair coat score. Neither the date of pasture burning nor the mineral type impacted cattle gains for all treatments. Cattle consuming mineral with spices had less flies through a majority of the grazing period. Even though SPICE cattle had less flies, the spice treatment did not result in improvements in gain as during the weeks where spice cattle had less flies than control, both treatments were over the economic threshold for horn flies (200 flies per steer). Additional years on this project will be completed to determine the effects of pasture burn date and addition of spices in mineral.

Identification of Breed Differences in Known and New Fescue Toxicosis Associated Phenotypes in Charolais-and Hereford-Sired Crossbred Beef Cows.

Simple SummaryThe consumption of toxic fescue has caused significant losses in the U.S. beef industry. Widely accepted symptoms of toxic fescue exposure include the retention of a thick hair coat, tissue necrosis in the extremities, and reduced nutrient absorption. However, there is variability in the severity of these symptoms, both across and within breeds. The objective of this study was to characterize the effect of fescue toxicosis across Hereford- and Charolais-sired cows for known and new fescue stress-associated phenotypes. Results indicated that Hereford cows had a lessened ability to shed their winter coat and regulate body temperature along with lower serum mineral concentrations compared to Charolais cows when exposed to toxic fescue. Differences between and within sire breed in hair shedding were also observed, providing further evidence of genetic variation. This study provides evidence of variability in the fescue toxicosis that is potentially useful for genetic selection to reduce fescue stress and characterizes effects on pregnant cows which may impact calves in utero.Beef cattle phenotypes are affected by the consumption of toxic fescue. Toxic fescue’s impact is dependent on heat stress and breed composition, with genetic variability for robustness to toxin exposure believed to exist within and across breeds. The study objective was to characterize the effect of fescue toxicosis across breeds for known and novel heat and fescue stress-associated phenotypes. One-hundred crossbred fall-calving Charolais- and Hereford-sired cows of parities 1–3 were allocated to graze either toxic fescue (n = 50), non-toxic fescue (n = 25), or a rotation between toxic and non-toxic fescue (n = 25) for 156 days. Phenotypes impacted by breed (genetics) included hair coat score (p < 0.0001), hair reduction/shedding rate (p < 0.05), rectal temperature (RT) (p < 0.0001), vaginal temperature (p < 0.05), serum phosphorus concentration (p < 0.02) and respiration rate (RR) (p < 0.003). Cows on toxic fescue experienced reduced hair shedding efficacy (p < 0.0001), higher vaginal temperatures (p < 0.0001), increased systolic blood pressure (p < 0.04), increased RR (p < 0.0001) and reduced average daily gain (p < 0.0001), compared to cows grazing non-toxic fescue. Calves born from cows with higher RT during the last third of gestation had higher RT at weaning (p < 0.02), indicating potential physiological effects of in utero heat stress. The study indicates that beef cows exhibit variable responses to toxic fescue within and across breeds which may impact future calf phenotypes.

43 Cow Performance and Lameness Are Affected by Housing in Drylots vs Pasture During the Summer

Abstract The objective was to compare the performance of cows housed in drylots or on pasture. Spring-calving, Simmental × Angus cow-calf pairs (n = 108; 77 ± 18 days postpartum) were stratified by age, body weight (BW), body condition score (BCS), calving date, and calf sex. Cows were allotted into six groups which were randomly assigned to drylot or pasture. Drylot cows were limit-fed a ration consisting of corn silage, dried distillers grain, corn stalks, cracked corn, and a corn-based supplement to meet protein and energy requirements. Cows on pasture were rotationally grazed with access to free-choice mineral. Cows were artificially inseminated on day 0. Cow BW, BCS, hair coat scores, locomotion scores, and lameness treatments were evaluated throughout the 110-day experiment. Milk production and composition were evaluated on day 56. Data were analyzed using the MIXED and GLIMMIX (binary data) procedures of SAS. Artificial insemination and overall pregnancy rates did not differ (P ≥ 0.79) between groups. Drylot cows were 22 and 51 kg heavier (P ≤ 0.02) than pasture cows on days 83 and 110, respectively. Drylot cow BCS was greater (P = 0.03) on day 110. Hair coat scores were more desirable (P = 0.03) in drylot cows than pasture cows on day 110. Drylot cows had greater (P = 0.04) milk production than pasture cows. Pasture cows had greater (P ≤ 0.03) milk protein content and milk urea nitrogen. Although locomotion scores did not differ (P ≥ 0.45) on days 0 and 34, they were less desirable (P = 0.02) for the drylot cows on day 110. A greater (P = 0.02) percentage of drylot cows (33%) were treated for lameness than pasture cows (7%). Housing cows in drylots increased BW, BCS, and milk production, but resulted in poorer locomotion scores and increased lameness treatments.

46 Effects of Implants, Clover, and Fescue Variety on Stocker Steers

Abstract Fescue thrives due to a symbiotic relationship with a fungus called endophyte. Endophyte releases ergot toxins leading to metabolic issues, such as vasoconstriction, rough hair coats and poor cattle gains. Developments have occurred to remove or limit the toxins. The objective of this project was to identify management practices while grazing fescue to improve production and toxicity issues. Sixty-four growing steers (283 ± 14 kg BW) were used in a split-plot experiment, where the whole plot was pasture and the split plot was implants. Whole plot treatment was a 4 x 2 factorial with four levels of fescue (High Endophyte, Low Endophyte, Novel, Endophyte Free) and two levels of legume (Legumes or No Legumes). Split plot included four implant levels (No Implant, Synovex One Grass, Revalor-G, Ralgro). Data collected were weights, hair coat scores, hair length, rectal temperature (every 28d) and ultrasound carcass characteristics last day on pasture. Data were analyzed using the Glimmix Procedure of SAS (v. 9.4, Cary, NC). Steers on high endophyte had the lowest ADG, longest hair, and highest temperature as compared to steers on all other fescue types (P &amp;lt; 0.05). The gain differentiation was observed beginning at D56 through the end of the study (P &amp;lt; 0.05). Overall ADG was not impacted by addition of legume nor implant type (P &amp;gt; 0.10). Steers that were not implanted had a longer hair length throughout many measurement dates (P &amp;lt; 0.05). Steers grazing pastures with legume tended (P &amp;lt; 0.10) to have a higher ultrasound measured marbling score and less muscle depth. This study found that the best management strategy for fescue toxicity is to use non-endophyte or non-toxic varieties of fescue pasture. Contrary to previous research, the addition of implants and legumes for this project showed no improvement in cattle gains.

Hair coat score in Angus cattle: Comparison of linear and threshold models, genetic gain and correlations with growth, morphological and reproductive traits

Hair coat traits are used as indicators of animal adaptation because of their importance for thermoregulation and parasites resistance. These traits are evaluated visually based on a score in some beef cattle breeding programs. Data from 38,800 Angus animals were used to compare linear and threshold animal models in order to validate genetic parameters for visual scores of hair coat at weaning (WHC) and yearling (YHC), and conformation (YC), precocity (YP) and muscling (YM) at yearling. The genetic trends for WHC and YHC and their relationships with YC, YP, YM, birth weight (BW), weight gain from birth to weaning (BWG) and from weaning to yearling (YWG), scrotal circumference (SC), and gestation length (GL) were also obtained. For WHC and YHC, higher heritabilities were estimated with the threshold models (0.249±0.039 and 0.295±0.041, respectively) compared to the linear models (0.188±0.029 and 0.218±0.032, respectively). However, similar heritabilities were obtained with the two models for YC, YP and YM. Rank correlations between sire breeding values predicted for WHC and YHC using linear and threshold models ranged from 0.75 to 0.95, considering the top 2 to 50% of the selected sires. For YC, YP and YM, small changes in sire ranking are expected when these models are used (rank correlations higher than 0.86), regardless of the proportion of selected sires. Cross-validation strategies by regression showed that genetic selection for all visual scores will also promote improvements in phenotypic performance. Genetic trends were significant (P<0.05) and favorable for WHC and YHC. The genetic correlation between WHC and YHC was high and positive (0.848±0.055). Favorable and moderate genetic associations were estimated for WHC and YHC with YC, YP, YM, BWG and WYG, ranging from -0.329±0.108 to -0.589±0.07. The genetic correlations of WHC and YHC with BW, SC and GL were weaker and negative. According to our results, the threshold model is recommended for genetic evaluation of WHC and YHC in this population, and both models are indicated for YC, YP and YM. In general, genetic selection to increase growth, YC, YP, YM and SC will simultaneously reduce WHC and YHC, favoring animals that are more adapted to the environmental conditions of the tropics.

PSI-2 Effects of extended release eprinomectin on heifer performance while grazed on endophyte-infected tall fescue or housed in drylot

Abstract Objectives were to evaluate the effects of LongRange, an extended-release eprinomectin, on beef heifer performance while grazed on endophyte-infected tall fescue or housed in drylot. Fall-born, Angus × Simmental heifers (n = 153) were utilized in a split-plot design. Heifers were stratified by BW and assigned to 6 groups. Groups were randomly assigned to 1 of 2 environmental treatments: grazed endophyte-infected tall fescue (Pasture) or housed in drylot and fed alfalfa hay. Within environmental treatment groups, heifers were randomly assigned to LongRange (LR) or control (Saline). Prior to experiment initiation, heifers were treated with oral fenbendazole (SafeGuard) to minimize parasite load. Data were analyzed using the MIXED procedure of SAS. At d 0, 56, and 112, heifer BW, ADG, BCS, hair coat score (HCS), and fecal egg counts (FEC) were collected. Treatments did not affect (P ≥ 0.17) BW on d 0 and 56. On d 112, drylot heifers tended (P = 0.08) to be heavier than pasture heifers and LR increased (P = 0.01) BW. There was an interaction (P = 0.02) for ADG; LR increased ADG to a greater magnitude in pasture than drylot heifers. On d 0, 56, and 112, there was no interaction or LongRange effect (P ≥ 0.11) on BCS; however, pasture heifers had greater (P = 0.05) d 112 BCS than drylot heifers. On d 56, there was an interaction (P = 0.01) on HCS; LR decreased HCS in pasture heifers, but did not affect HCS in drylot heifers. Although treatment did not effect (P ≤ 0.33) FEC at d 0, there was an interaction (P = 0.01) observed on d 56. LongRange decreased FEC in pasture heifers but not in drylot. In conclusion, LongRange increased heifer growth performance with a greater difference for heifers grazing tall fescue, compared with heifers in drylot.

PSIV-26 Effects of extended-release eprinomectin on heifer growth and reproductive performance while grazed on endophyte-infected tall fescue or housed in drylot

Abstract The objective was to assess the effects of an extended-release eprinomectin (LongRange) on beef heifer reproductive performance when grazed on endophyte-infected tall fescue or housed on drylot. In a split-plot design, fall-born, Angus × Simmental heifers (n = 153) were stratified by BW and divided into 6 groups. Groups were randomly assigned environmental treatments: grazed endophyte-infected tall fescue (pasture) or maintained in drylot and fed alfalfa hay. Within a group, heifers were randomly assigned to LongRange (LR) or saline (control). Heifers were dewormed with oral fenbendazole (SafeGuard) to minimize parasite load before trial initiation. On d 140 and final pregnancy check, body weight (BW) and body condition score (BCS) were collected; BW was also collected at time of artificial insemination (AI). Hair coat score (HCS), fecal egg count (FEC), packed cell volume (PCV), and respiration rates (RR) were collected on d 140. Data were analyzed using the MIXED procedure of SAS. Environment × treatment effects for BW were detected (P ≤ 0.01) at d 140 and at overall pregnancy confirmation; LR increased BW to a greater magnitude in pasture than in drylot heifers. At breeding, LR increased (P = 0.01) heifer BW compared to control. On d 140, LR increased (P = 0.01) heifer BCS compared to control. On d 140, pasture heifers tended (P = 0.08) to have greater RR than drylot heifers. Heifer AI pregnancy rates were not affected (P ≥ 0.21) by treatments. Environment × treatment effects for overall pregnancy were detected (P = 0.03); LR increased overall pregnancy rate in pasture compared to drylot heifers and LR tended to increase overall pregnancy rate compared with control in pasture heifers. In conclusion, LongRange increased BW to a greater extent in pasture than in drylot and tended to increase heifer final pregnancy rate compared to control on pasture.

94 Impact of a Hydrolyzed Yeast Product on Performance, Hair Coat Shedding, and Behavior of Cows Grazing Pastures Containing Endophyte-Infected Tall Fescue

Abstract Endophyte-infected tall fescue creates a multitude of problems for many beef producers, with supplementation being one management strategy to decrease these problems. Our research objective was to determine if supplementation with a hydrolyzed yeast product could alleviate some symptoms of fescue toxicosis in mature cows. Across the 3-yr study, Angus cow-calf pairs (n = 34, 38, 34) were stratified by cow age and body weight then randomly allotted to one of two treatments; control mineral (CON) or hydrolyzed yeast mineral (HYM). Cattle in both treatment groups grazed the same mixed grass pastures (n = 6, 8, 8; 1.21 ha each) which contained varying levels of endophyte (20 – 90%) as measured prior to each year, in a rotational pattern for 126, 133, or 140 d, depending upon year. Prior to entering a new pasture weekly, cows were weighed and assigned a BCS and hair coat score (HC) by two independent, trained personnel. Cow behavior was measured every 15-min within a 2-h block weekly. Percentage of cows active or inactive, outside or inside a barn was recorded. Data were analyzed using the MIXED procedure of SAS. Cow BW change was affected (P &amp;lt; 0.01) by a treatment×year interaction. Cow BCS increased in HYM vs. CON cows (0.34 vs. 0.06; P &amp;lt; 0.01; SEM = 0.08) across the entire trial. Cows consuming the HYM supplement also spent a greater percentage of time outside being active (P &amp;lt; 0.01) and a lower percentage of time inside being inactive (P &amp;lt; 0.01) compared to CON cows. Results from this trial indicate that the hydrolyzed yeast mineral may be an effective tool to aid in combating heat stress associated with fescue toxicosis.

Evaluation of a commercial genetic test for fescue toxicosis in pregnant Angus beef cattle.

Most tall fescue [Lolium arundinaceum (Schreb.) Darbysh] in the Southeastern United States contains an endophyte that causes fescue toxicosis (FT) in grazing animals, a serious disease that causes approximately $1 billion in economic losses to the animal industries in the United States. Recently, a genetic test called T-Snip (AgBotanica, LCC, Columbia, MO), was developed with the objective of identifying animals with genetic variation for FT tolerance. The aim of this study was to validate the use of this genetic test in mature, pregnant cows. Over 13 wk, weekly phenotypic data, including body weight, rectal temperatures, hair coat scores, hair shedding scores, and body condition scores, were collected on 148 pregnant purebred Angus cows at 2 locations in NC where infected fescue was the primary source of feed. Birth weights (cBW) and 205-d adjusted weaning weights (adjWW) from these cow’s calves were recorded. All cows were genotyped for T-Snip. At the end of the trial, each phenotypic trait was calculated as the slope of the linear regression of performance on weeks. The effect of T-Snip rating genotypes (4 levels) on slope traits was tested using a linear model also including the fixed-effects of location, parity, and the initial measurement for each trait (covariate). For cBW and adjWW, the model also included the sex of the calf and the month of birth as categorical effects. Associations of T-Snip genotypes were observed for body weight gain (aBWd) of pregnant cows (P = 0.15; interaction with location), change in body condition score (aBCSd; P = 0.13), and adjWW (P = 0.06; interaction with location). For aBWd and adjWW, associations were found just within one location (P = 0.017 and 0.047, respectively), which was the location with higher endophyte infection rate. For all associations, the direction of the T-Snip genotypes was the same and as expected: the greater the genotype score, the better performance. No associations were found for the other traits (P > 0.10). These results indicate that the T-Snip test may be predictive of cow performance (aBWd, aBCSd, and adjWW) in an endophyte-infected tall fescue environment.

159 Relationships among circulating prolactin concentrations, hair coat score, and weights of grazing cows

Abstract Prolactin (PRL) is a pleiotropic protein hormone synthesized and released from the anterior pituitary. Concentrations of PRL can serve as a biomarker of cattle exposure to ergot alkaloids. Our objective was to determine relationships among prolactin concentrations, hair coat score, and body weights of non-lactating crossbred beef cows (n = 71). Cows were weighed, hair coat scored (1 = 100% shed, and 5 = 0% shed), and blood samples collected in May, June, and July. Cows were grazing mixed grass pastures that included native endophyte-infected tall fescue. Serum PRL concentrations were determined by validated RIA. Based on May samples, cows were categorized as high (n = 11; 159 ± 29 ng/mL PRL), medium (n = 48; 51 ± 4 ng/mL PRL), or low (n = 12; 21 ± 4 ng/ mL PRL). Data were analyzed with Pearson correlations, and repeated measures ANOVA with month and prolactin category (PRLCAT) as main effects. Concentrations of PRL were correlated (r &amp;gt; 0.53; P &amp;lt; 0.0001) over the three months, and May PRL concentrations were correlated (r &amp;gt; 0.29; P &amp;lt; 0.02) with cow body weights in May, June, and July. Cows in the low PRLCAT had lower (P &amp;lt; 0.01) concentrations of PRL in all three months. Hair coat score decreased (P &amp;lt; 0.0001) each month (4.3, 2.7, and 1.3; respectively, May, June, July), and was higher (P &amp;lt; 0.05) for cows with low PRLCAT (3.3 vs. 2.7 and 2.4 for low, medium, and high, respectively). Cow body weight increased (P &amp;lt; 0.0001) from May to July. Cows in the low PRLCAT had lower (P &amp;lt; 0.05) body weights than medium and high PRLCAT cows (484 vs. 555, and 575 kg; respectively). Concentrations of PRL in May could be useful in identifying cattle with slick hair coats and heavier body weights.

123 Effect of a hydrolyzed yeast product on cow behavior, body eeight, body condition score, and hair coat score in cows grazing pastures containing endophyte-infected tall fescue

Abstract The objective of this study was to determine if the addition of a hydrolyzed yeast product would alleviate the symptoms of fescue toxicosis in beef cattle. Thirty-eight Angus cow-calf pairs were stratified by cow age and body weight then randomly allotted to one of two treatments; control mineral (CON) or hydrolyzed yeast mineral (HYM). Cattle in both groups were allowed access to mineral for 126 d while they grazed the same eight pastures (1.21 ha each) in a rotational pattern. Mineral was provided at a target rate of 113.4 g·hd-1·d-1 every 28 d. Each pasture was grazed by cattle groups for 7 d. Mixed grass pastures containing tall fescue were utilized and evaluated for endophyte level prior to the start of the project. Due to pasture endophyte level variability (44%-73% endophyte), both groups of cattle rotationally grazed each pasture at least 2 times starting in June. Prior to entering a new pasture weekly, cows were weighed and assigned a BCS and hair coat score (HC) by two independent, trained personnel. Cow behavior was measured every 15-min within a 2-h block weekly. Percentage of cows active or inactive, outside or inside was recorded. Data were analyzed using the MIXED procedure of SAS. Cow BW change was unaffected by treatment (P &gt; 0.23). Cow BCS significantly increased in HYM vs. CON cows (0.4 vs. 0.1; P = 0.02; SEM = 0.1) through the 126 d project. No treatment effect was observed on HC (P &gt; 0.19). Cow behavior was impacted by treatment, as HYM cows spent more time outside compared to CON cows (P &lt; 0.01). Results of this trial suggest that HYM cows may have experienced less heat stress as a result of fescue toxicosis as they were willing to spend more time outside and increased BCS.

13 Effect of housing cow-calf pairs on dry lots vs pasture on calf performance and behavior

Abstract The objectives were to analyze the effects of housing cow-calf pairs in dry lots (DL) or pasture (PAST) on calf performance and behavior through the receiving phase. Simmental × Angus (n = 108; 87 ± 11.5 d postpartum) spring-calving cows were stratified by age, BW, BCS, and calf sex and allotted to six groups. Cows were limit-fed a ration consisting of corn silage, dried distillers grain, corn stalks, dry rolled corn (DRC), and soybean hulls to meet protein and energy requirements. Calves had ad libitum access to same diet in an adjacent pen. Calves on PAST were rotationally grazed with free-choice mineral. After weaning (177 ± 11.5 d of age) all calves were fed a diet consisting of corn silage, wet distiller grains, DRC, and grass hay during the receiving phase (42 d). At the age 87, 142, 177, 198, and 219 ± 11.5 d, BW was measured. Hair coat score (HCS) and dirt score (DS) were measured on d 0 and d 90. Calf behavior was observed after feedlot arrival. Average daily gain, DMI and feed efficiency were also analyzed. The data were analyzed using the MIXED procedure of SAS. Dry-lot calves had greater (P &lt; 0.01) BW and ADG prior to weaning. Calves from PAST had lower (P &lt; 0.01) DS and greater (P &lt; 0.01) HCS at weaning. Upon feedlot arrival, more (P &lt; 0.01) DL calves were walking and had increased (P &lt; 0.01) vocalizations. Calves from PAST had greater (P &lt; 0.01) ADG, DMI as a percent of BW, and gain:feed than DL calves during the receiving phase. Calves raised in a dry lot had greater BW and ADG prior to weaning, but PAST calves had fewer behavioral signs of stress and greater growth performance in feedlot.