Effect of previous locoweed (Astragalus and Oxytropis species) intoxication on conditioned taste aversions in horses and sheep

Locoweed species (Astragalus and Oxytropis spp.) are a serious toxic plant problem for grazing livestock. Horses and sheep have been conditioned to avoid eating locoweed using the aversive agent LiCl. The objective of this study was to determine if previous locoweed intoxication affects food aversion learning in horses and sheep. Horses and sheep were divided into 3 treatment groups: control (not fed locoweed and not averted to a novel feed); locoweed-novel feed averted (fed locoweed and averted to a novel feed); and averted (not fed locoweed and averted to a novel feed). Animals in the locoweed-novel feed averted groups were fed locoweed during 2 periods of 21 and 14 d, respectively, with each feeding period followed by a 14-d recovery period. Animals were averted to a novel test feed at the end of the first locoweed-feeding period, and periodically evaluated for the strength and persistence of the aversion. During the first recovery period, locoweed-novel feed averted horses ate less (9.5% of amount offered) of the test feed than did control horses (99.8%) and did not generally differ from averted horses (0%). During recovery period 2, locoweed-novel feed averted horses (4.3%) differed (P = 0.001) in consumption (% of offered) of the test feed from controls (100%) and the averted group (0%). Locoweed-novel feed averted sheep differed (P = 0.001) from controls (14.4 vs. 99.5%, respectively, during recovery period 1), whereas locoweed-novel feed averted sheep did not differ (P > 0.50) from averted sheep (0.6%). During the second recovery period, control sheep (100%) differed (P < 0.05) from averted (0%) and locoweed-novel feed averted (12.2%) groups. Two intoxicated sheep (locoweed-novel feed averted) partially extinguished the aversion during the first recovery period, but an additional dose of LiCl restored the aversion. Two of 3 intoxicated horses had strong aversions that persisted without extinction; 1 horse in the locoweed-novel feed averted group had a weaker aversion. These findings suggest that horses and sheep previously intoxicated by locoweeds can form strong and persistent aversions to a novel feed, but in some animals, those aversions may not be as strong as in animals that were never intoxicated.     

Grazing of spotted locoweed (Astragalus lentiginosus) by cattle and horses in Arizona

Spotted locoweed (Astragalus lentiginosus var. diphysus) is a toxic, perennial plant that may, if sufficient precipitation occurs, dominate the herbaceous vegetation of pinyon-juniper woodlands on the Colorado Plateau. Six cow/calf pairs and four horses grazed a 20-ha pasture with dense patches of locoweed in eastern Arizona during spring 1998. Locoweed density was 0.7 plants/m2 in the pasture. Locoweed averaged 30.4% NDF and 18.4% CP. Concentrations of the locoweed toxin, swainsonine, fluctuated from 1.25 to 2 mg/g in locoweed. Horses ate more (P < 0.01) bites of locoweed than did cows (15.4 and 5.1% of bites, respectively). Horses generally increased locoweed consumption over time since they ate approximately 5% of bites in the preflower stage compared with 25% of bites in the pod stage. Cattle consumed almost no locoweed (< 1% of bites) until the pod stage, when they increased consumption to 15% of bites. Horses were very avid (approximately 65 to 95% of bites) in selecting the small quantities (approximately 40 to 150 kg/ha) of available green grass, and it appeared that their propensity to eat scarce green forage influenced their locoweed consumption as well. Horses ate relatively little dry grass, even when it was abundant, whereas cattle ate large amounts of dry grass until green grasses became more abundant. Calves began eating locoweed on the same day as their dams and ate approximately 20% of their bites as locoweed. Serum concentrations of swainsonine were higher (P < 0.05) in horses than in cattle (433 vs. 170 ng/mL, respectively). Baseline swainsonine was zero in all animals, but swainsonine was rapidly increased to above 800 ng/mL in serum of horses as they ate locoweed. Horses exhibited depression after eating locoweed for about 2 wk; after 5 wk of exposure, horses became anorectic and behaviorally unstable. Although limited in scope, this study indicates that horses should not be exposed to spotted locoweed.     

Continuous exposure to an aversive mixture as a means of maintaining aversion to vermeerbos (Geigeria ornativa O. Hoffm.) in the presence of non-averted sheep

Continuous exposure to an aversive mixture was investigated as a means of maintaining aversion to vermeerbos in sheep subjected to the social influence of non-averted sheep. The use of an aversive mixture was based on a hypothesis that continuous exposure to an acceptable aversive mixture (containing both the aversive substance and the identification factors of vermeerbos mixed with maize meal) would tempt sheep to consume small quantities of the aversive mixture each day and that this would keep them averted to vermeerbos, despite the social influence of non-averted sheep. Persistent aversion to a vermeerbos-maize meal mixture (1:99 by mass) by sheep continuously exposed to such an aversive mixture, after an initial aversion conditioning with lithium chloride (LiCl, 160 mg/kg BM), was demonstrated. Aversion in adjacent controls not exposed to the aversive mixture only lasted for some time. A similar result was obtained when sheep were challenged for intake of a pure stand of established vermeerbos. Three sheep continuously exposed to an aversive mixture after an initial aversion conditioning totally refused grazing the vermeerbos during a 42-day trial, despite the social influence of three non-averted control sheep grazing vermeerbos on an adjacent site. These results were confirmed by a second replication the following year. Joint grazing for an hour a day by averted and non-averted sheep during the last seven days of this replication also resulted in total avoidance of vermeerbos by the averted animals, despite continued intake of vermeerbos by the control sheep     

Comparison of larkspur alkaloid extract and lithium chloride in maintaining cattle aversion to larkspur in the field.

Lithium chloride (LiCl) and larkspur (Delphinium barbeyi) alkaloid extract were compared in their effect as an emetic to create taste aversions to fresh larkspur. They were further compared in the field to determine whether the indigenous larkspur alkaloids were more effective in maintaining the aversion when conditioned cattle were subjected to the social pressure (social facilitation) of control cattle eating larkspur. Taste aversions were produced in two groups of 1-yr-old cattle by offering fresh larkspur and then gavaging with either LiCl at 200 mg/kg of BW or larkspur alkaloid extract at 1.1 to 1.6 mL/kg of BW. The third group (control) was gavaged with water. The alkaloid group was slower to form an aversion than the lithium group, requiring four doses compared with two doses. All groups were then taken to larkspur-infested rangeland to test the aversion in the field. In the first field trial in which groups grazed separately, both aversion-induced groups generally abstained from eating larkspur. In the second trial in which all groups grazed together, both aversion-induced groups consumed less than half as much larkspur as the controls, but neither group abstained completely. Larkspur alkaloids did not maintain the aversion to larkspur to a greater degree than did LiCl when aversion-induced cattle were subjected to social facilitation.     

Conditioned feed aversion as a means to prevent tulp (Homeria pallida) poisoning in cattle

Conditioned feed aversion was investigated as a means to prevent tulp (Homeria pallida) poisoning in cattle on tulp-infested grazing. Aversion treatment with a combination of epoxyscillirosidin and lithium chloride together with a tulp-hexane extract, which served as identification factor for tulp, resulted in a significantly lower (P < 0.001) proportion of severe tulp poisoning. In a first trial where 21 averted and 21 non-averted control cattle were exposed to a tulp-infested grass pasture, only two of the averted cattle were severely poisoned compared to 13 of the non-averted control cattle. In a second trial, with cattle being exposed to a pure stand of tulp supplemented with maize residues, only two of 21 averted cattle were severely poisoned compared to 14 of 21 non-averted control cattle. Occurrence of mild tulp poisoning, however, did not differ much between averted and non-averted control cattle. The results show that conditioned feed aversion effectively restricted severe poisoning in cattle on tulp-infested grazing.     

Feed aversion induced by intraruminal infusion with larkspur extract in cattle

Twelve Hereford heifers were infused with larkspur extract (group 1, n = 4), lithium chloride solution (group 2, n = 4), or sodium chloride solution (group 3, n = 4). After 3 weeks of being fed basal ration (meadow grass hay), all heifers were offered a ration of alfalfa pellets (3,400 g) in a 2-phase, single-day feeding regimen. In phase 1, the amount eaten within 45 minutes was measured by weigh-back of uneaten pellets. In phase 2, cattle that ate greater than 150 g of pellets in phase 1 were offered the balance of uneaten pellets and were infused with their respective designated solution. Five pairings of pellet feedings and appropriate infusions were given at 2- or 3-day intervals to initially induce feed aversion. Heifers in groups 1 and 2 developed a strong aversion to pellets by the 5th feeding. Persistence of aversion was tested twice at weekly intervals. Infusion of cattle with larkspur extract or lithium chloride solution induced a persistent aversion to an otherwise palatable feed.     

Adverse influence of social facilitation and learning context in training cattle to avoid eating larkspur

Through conditioned food aversion learning, livestock can be trained to avoid eating harmful plants. The objectives of this study were to determine whether social facilitation will extinguish an aversion to larkspur (a poisonous plant on mountain rangelands) and to determine whether the aversion can be reinforced to withstand social facilitation in a group-feeding and field-grazing situation. Two groups of heifers offered fresh larkspur were simultaneously infused intraruminally with lithium chloride (LiCl) to create an association between the taste of larkspur and LiCl-induced gastrointestinal distress. A third control group was infused with water. Heifers from one averted group (extinction) were paired with nonaverted controls and offered larkspur. When the extinction group sampled larkspur, and LiCl was not infused, the aversion was extinguished rapidly. Heifers in the other averted group (reinforcement), being infused with LiCl whenever they sampled larkspur, abstained from eating larkspur in the group-feeding situation. Heifers were then taken to larkspur-infested rangeland. After the control heifers began eating larkspur, the averted heifers started to sample it and the aversion was extinguished in three of four heifers. However, the aversion was renewed when the heifers were returned to the pen- and group-feeding situation where the aversion was created. Reinforced aversion was overcome by social facilitation in an unfamiliar field-grazing environment.     

Modestly Improved Compliance and Apparent Comfort of Horses With Aversions to Mildly Aversive Routine Health Care Procedures Following Short-Term Alpha-Casozepine Supplementation

Alpha-casozepine, a decapeptide derived from bovine milk α-_S1 casein, has well-documented anxiolytic properties in several species. To evaluate potential benefit of alpha-casozepine to horses' compliance and comfort with routine management and health care procedures, we blindly compared behavior of alpha-casozepine–supplemented and control-supplemented horses with known specific aversions to specific health care procedures. Twenty-six light horse mares were first screened for aversions based on compliance and apparent comfort during a standard battery of 12 health care examinations and treatment procedures. Based on quantitative behavioral analysis of video-recorded sessions, baseline compliance and/or comfort with each procedure was scored from 0 (unable to progress) to 10 (excellent compliance and relaxed comfort). Based on those results, 10 of the 26 horses were selected as five pairs that were matched for breed and the same two specific aversions. One of each pair was randomly assigned to alpha-casozepine supplementation (2,000 mg PO daily) and the other to control supplement for 5 days. On day 5 of supplementation, the standard battery of 12 procedures was repeated. For the five alpha-casozepine–supplemented subjects, compliance and/or comfort scores improved for seven of their 10 aversions compared with one of 10 for the five matched controls (P < .01, Fisher Exact). Average score increased 1.5 (standard error [SE] = 0.87) points for alpha-casozepine aversions compared with an average decrease of 0.92 (SE = 0.61) points for matched control aversions (P < .05, Wilcoxon signed ranks). These results indicate a modest benefit of alpha-casozepine supplementation to horses for improvement of compliance and apparent comfort with mildly aversive routine health care procedures.     

Differences in grazing behavior of horses and cattle at the feeding station scale on woodland pasture

In this study, grazing behavior of mares and cows was compared on woodland pastures, in the context of foraging hierarchy. A horse‐group (12 native Hokkaido horses) and a cattle‐group (5 Hereford cows) were grazed on the woodland pastures of 13.3 ha and 5.8 ha, respectively. They grazed mainly on Sasa nipponica. Grazing behavior at a feeding station (FS) scale was recorded for three focal animals in each group. Mares took one bite per FS at a high percentage of FSs (24.3%) and cows took one, two and three bites per FS at high percentage (20.3%, 19.2% and 15.4%, respectively). Although feeding patch (FP) scale for both animals could be defined as a group of FSs, the length of FP and grazing behavior at FP scale were similar for both animals. The number of steps taken between two adjacent FSs or FPs for mares was larger than that for cows. The results suggested that both horses and cattle had similar foraging hierarchy from bite to FP scale but grazing behavior of horses at the FS scale was different from that of cattle, suggesting that grazing behavior of large herbivores has greater similarity in larger foraging hierarchies.     

Behavioral and Ecological Implications of Bunched,Rotational Cattle Grazing in East African Savanna Ecosystem

Rangelands and the wildlife and livestock they support are critical to human livelihoods, but rangeland ecosystems increasingly suffer from overgrazing and degradation. Planned grazing, a strategy that commonly involves time-controlled rotations of high-density (bunched) groups of cattle across a pasture, is marketed as a method to enhance rangeland health and lessen livestock impacts. However, the behavioral mechanisms underlying any potential rangeland improvements resulting from rotational, high-density planned grazing have rarely been examined. To investigate these mechanisms, we compared planned grazing with conventional continuous grazing management in a savanna ecosystem in Kenya. We surveyed cattle grazing behavior, measured changes in vegetation characteristics through surveys conducted before and after cattle grazing, and measured native ungulate abundance following grazing using camera traps. Stocking rates were held constant across treatments, resulting in a commensurate decline in total foliar hits per pin (a proxy for vegetative biomass) across treatments. Planned grazing management altered cattle behavior and reduced grazing selectivity by restricting movements, causing cattle to walk more slowly while grazing and to take more bites per step. Vegetation survey results supported this finding: cattle in the planned grazing treatment ate significantly more Pennisetum grasses (typically avoided because of their unpalatability), creating the opportunity for regrowth of more palatable species after seasonal rains. We also documented significantly higher zebra presence in planned grazing plots after cattle grazing, likely due to increased relative abundance of more palatable grass species. This investigation of grazing behavior, and specifically decreased grazing selectivity as a mechanism underpinning the benefits of planned grazing, shows that when conducted at appropriate stocking densities, planned grazing has the potential to help mitigate rangeland degradation and improve rangeland sustainability for both livestock and wildlife in pastoral African savanna ecosystems.     

Effects of an Estradiol Implant on Locoweed Consumption,Toxicity, and Recovery in Growing Beef Steers

Two experiments were conducted to determine effects of an estradiol implant (Compudose®) on locoweed consumption and toxicity in growing steers. In Exp. 1, 16 crossbred steers (185.3 ± 6.1 kg) were randomly assigned to two replicated treatments and received either an estradiol implant or no implant. Steers were assigned to one of four pastures and were rotated through all pastures, which differed in locoweed distribution, to allow equal access. Bite counts were recorded twice daily at 0600 and 1700 h during a period when steers were likely to consume locoweed. For bite counts, steers were observed for 5 min each, starting at 0600 and at 1700 h, and the number of bites taken of cool- and warm-season grasses, forbs, and locoweed were recorded. Blood was collected on d 0, 7, 28, 35, 63, and 119, and individual BW was recorded on d 0, 35, 63, and 119. Proportion of bites of locoweed consumed by implanted vs nonimplanted steers did not differ (P>0.10). Likewise, ADG, serum alkaline phosphatase activity, and thyroxine concentrations did not differ (P>0.10) between implanted and nonimplanted steers. In Exp. 2, 20 crossbred steers (212.3 ± 6.1 kg) were divided into four groups and individually fed in a 2 × 2 factorial arrangement of treatments. Treatments included: 1) estradiol implant + locoweed, 2) implant, no locoweed, 3) no implant + locoweed, and 4) no implant, no locoweed. Steers were implanted at d 0 and fed either a ground forage diet containing 80% sudangrass hay and 20% locoweed, or a diet of 100% sudangrass hay. Implanted steers had improved ADG vs nonimplanted steers (P<0.10) through 63 d on trial, but no differences were observed in steers fed locoweed vs sudangrass hay diets (P>0.90; locoweed x implant, P>0.10). Alkaline phosphatase activity was greater (P<0.05) for steers fed locoweed vs those not receiving locoweed on d 7, 14, and 21, whereas, thyroxine concentration was lower (P<0.06) in steers fed locoweed than those not fed locoweed on d 14 and 21. Estradiol concentrations were greater in implanted steers vs those not implanted (P<0.05). These results suggest no effect of an estrogen implant on locoweed consumption or on severity of locoweed toxicity by beef steers.     

Role of horse flies in transmission of wquine infectious anemia from carrier ponies

Equine infectious anemia virus was transmitted from an acutely ill and an inapparently infected pony to uninfected ponies by the interrupted feeding of horse flies (tabanids). Transmission from acutely ill ponies was not accomplished following: (1) the interrupted feeding of a single horse fly, (2) bites of horse flies that had fed on an acutely affected pony 24 hours earlier, (3) bites of horse flies that had oviposited after feeding on an acutely affected pony, or (4) the inoculation of larval material derived from horse flies that had fed to repletion. It was concluded that horse fly transmission of equine infectious anemia virus is mechanical only and that infected horses that are free of clinical signs can be a source of virus for insect transmission.     

Cattle grazing Wahweap milkvetch in southeastern Utah

Cattle's grazing of the locoweed Wahweap milkvetch (Astragalus lentiginosus var. wahweapensis) was evaluated on desert and foothill winter range during the winter of 1986 to 1987. Dry, dead stalks of Wahweap milkvetch that had grown in 1985 and 1986 made up 15% of cattle diets overall, and 24% of diets when cattle grazed gravelly benches where it was abundant. Nutritional quality of Wahweap milkvetch was higher than of most associated forage, but its alkaloid concentration varied among the senescent stages. One cow aborted and two cows developed clinical signs of locoweed poisoning, including water belly (hydrops amnii). Microscopic lesions consisting of cytoplasmic foamy vacuolation were evident in both the dam and fetus. Because senescent stalks of Wahweap milkvetch are palatable and readily grazed by cattle, ranchers should not permit cattle to graze infested sites until other green forage is available in the spring.     

Cattle Grazing Toxic Delphinium andersonii in South-Central Idaho

Anderson larkspur (Delphinium andersonii A. Gray) is a toxic plant responsible for cattle death losses in the western United States. The objectives of the present study were to determine when cattle consumed Anderson larkspur in relation to plant phenology and toxicity, and to determine if animal age influenced selection of Anderson larkspur. These grazing studies were conducted on semiarid sagebrush rangeland near Picabo, Idaho. Eight 6–7-yr-old mature Angus cows were used in 2008, whereas during 2009, 12 Angus cattle were used, including six yearling heifers and six 4-yr-old cows. The overall density of Anderson larkspur was 2.8 plants · m^?2 during 2008, and 4.9 plants · m^?2 during 2009. Total toxic alkaloid concentrations in Anderson larkspur plants were near or above 5 mg · g^?1 during both studies. During 2008 consumption peaked during the late flower and pod stage of growth. Overall in 2008 cows ate 3% of their bites as larkspur. During 2009 heifers ate about twice as much Anderson larkspur as did mature cows (5.1% of bites vs. 2.9%, respectively). Heifers repeatedly consumed sufficient larkspur that they collapsed; however, no animals were fatally intoxicated. Heifers appeared to become transiently averted to larkspur; however, heifers resumed consumption of D. andersonii after a period of one to several days of low or no consumption. Livestock management to reduce losses to Anderson larkspur should include timed grazing to avoid infested pastures during full flower to pod phenological stages, and grazing with older animals rather than yearling heifers.     

A preliminary answer to the question of whether cribbing causes salivary secretion

It has been hypothesized that cribbing, the equine oral stereotypy, may increase salivary production and, therefore, reduce gastric acidity in a species prone to gastric ulcers. To test the hypothesis that cribbing stimulates salivary secretion, parotid salivary duct fistulas were surgically created in 2 horses. In the first experiment, saliva was collected while the number of crib bites was counted. There was no significant relation (r² = 0.022) between the numbers of crib bites and the volume of saliva produced. The second experiment involved measuring salivary output when one horse was cribbing and when he was eating, but could not crib. Before feeding, the horse produced 1 (0-2) mL of saliva while displaying 20 crib bites. The horse produced 31 (2-212) mL of saliva while eating 200 g of grain. After eating, the horse produced 2 (1-10) mL of saliva while displaying 20 crib bites. There was a significant difference in saliva production associated with eating (Kruskal–Wallis statistic = 12.42, P < 0.02). Fifteen to 30 times more saliva was produced while eating than while cribbing. These preliminary findings indicate that in those 2 cribbing horses, saliva production was not increased during cribbing, thereby questioning the hypothesis that saliva production during cribbing leads to decrease in gastric acidity.     

Determination of Pasture Dry Matter Intake Rates in Different Seasons and Their Application in Grazing Management

Eight mature horses weighing 576 ± 32 kg (mean ± SD) were used to compare differences in pasture dry matter (DM) intake rate in October (period 1), February (period 2), and May (period 3). Horses were randomly assigned to a pair of adjacent 5 m × 5 m grazing cells containing nontoxic, endophyte-infected tall fescue. Horses had access to each cell for 4 hours. Pasture DM intake rate was estimated over the entire 8-hour period by measuring the pre- and postgrazing herbage mass within each cell and was expressed as kg DM/100 kg body weight (BW)/hr. Mean 8-hour DM intake rate in period 1 (0.17 ± 0.01 kg DM/100 kg BW/hr) was greater (P < .001) than for period 2 (0.09 ± 0.01 kg DM/100 kg BW/hr) and period 3 (0.11 ± 0.01 kg DM/100 kg BW/hr), but it was not different (P = .274) between periods 2 and 3. A second experiment using the same eight horses was conducted immediately after the first experiment, within each season, to determine whether the DM intake rates derived from the first experiment could be used along with estimates of maintenance digestible energy (DE) requirements and pasture DE concentrations to predict the amount of grazing time required for a horse to consume only its maintenance DE requirement and maintain zero BW change over a 6-week period. Grazing time necessary to maintain zero BW change was accurately predicted for period 1 only.     

Conditioning cattle to graze broom snakeweed (Gutierrezia sarothrae)

Broom snakeweed (Gutierrezia sarothrae) is the most widespread range weed in North America. We attempted to positively condition cattle to graze broom snakeweed to create a biological tool to decrease the competitive ability of snakeweed in a plant community. Fifteen yearling heifers were divided into three treatment groups receiving different supplements: 1) cornstarch, 2) starch with ground snakeweed, and 3) a control (no supplements). Heifers were fed fresh snakeweed, and then were gavaged with the respective supplements to provide positive feedback to enhance their acceptance of snakeweed. The starch group consumed more snakeweed in the pen conditioning trial (P = 0.02). The starch and control groups were then taken to the field for two grazing trials. In the spring grazing trial, there was no snakeweed consumed in the free-ranging part of the trial; however, when the pasture size was decreased, the heifers started to consume snakeweed as alternative forages became less abundant. In the second small pasture trial, heifers in the positively conditioned group consumed more snake-weed than those in the control group (16 vs. 5% of bites, P < 0.001). In the fall grazing trial, little snakeweed was consumed in the free-ranging part of the trial. When the pasture size was decreased, both positively conditioned and control groups increased snakeweed consumption up to 35% of bites. In the small pastures of both the spring and fall grazing trials, 36 to 59% of snakeweed plants were grazed. Cattle can be forced to graze snake-weed in a short-duration, high-intensity grazing strategy.     

Conditioning taste aversion to Mascagnia rigida (Malpighiaceae) in sheep

The objective of this study was to determine if sheep could be averted to Mascagnia rigida, a toxic plant found in the semiarid region of northeastern Brazil. Twelve female sheep naïve to M. rigida were randomly allocated to two treatment groups: control (treated with 15 mL water orally by a drenching gun) and lithium group (treated with 150 mg LiCl/kg body weight orally by a drenching gun). For conditioning, sheep were allowed to feed on M. rigida leaves for 15 min, followed by LiCl or water administration. The time spent eating M. rigida leaves was measured. The conditioning was repeated daily until the LiCl-treated sheep stopped eating M. rigida, which occurred at days 2 and 3. Persistence trials were conducted on day 10, 24, 40, 55, and 70 of the trial using single-choice tests. There was no difference between the two treatment groups with respect to the consumption of M. rigida on the first day of aversion conditioning. On the second day, three out of the six sheep in the lithium group did not eat the leaves, but on the third day, all the sheep in the lithium group did not ingest M. rigida. This aversion persisted throughout all the persistence trials. This indicates that sheep can be easily conditioned by using lithium chloride to avoid eating M. rigida.     

Equine grazing preferences among winter annual grasses and clovers adapted to the southeastern united states

Forage acceptability of five cool season annual grasses and four annual clovers to yearling horses was evaluated in Georgia during winter and spring of two years. With cafeteria grazing trials, preference in consumption was determined by difference in forage harvested from mower strips before and after grazing. In four test grazing periods,annual ryegrass was preferred (P<.05) by the yearlings, averaging 75% apparent consumption of the dry forage. Oats and wheat were second in preference, averaging 47 and 41% respectively. Rye and triticale were least preferred, averaging only 35 and 32% apparent consumption, respectively. Of the annual clovers tested, crimson, berseem, and subterranean were all highly palatable (P<.05) to horses with an average consumption of 71% across all three clover varieties. Arrowleaf clover was unacceptable (P<.05), having only 22% apparent consumption. Yearling horses avoided grazing rye, triticale, and arrowleaf clover when other forages were available.     

Dry Matter Intake,Body Weight,and Body Condition Scores of Blanketed and Nonblanketed Horses in the Upper Midwest

Thermoregulation is an energy-expensive process, which can be mitigated by blanketing horses in cold climates, potentially preventing weight loss or leading to decreased feed intake. The objective of this study was to evaluate feed intake, body weight (BW), and body condition scores (BCSs) in blanketed and nonblanketed horses. In October 2019, 16 mature adult horses were blocked by breed and BCS and randomly assigned to a blanketed (n = 8) or nonblanketed (n = 8) treatment; blankets were placed. Data were collected in December 2019 and January 2020 in River Falls, Wisconsin. During the study, horses were housed in dry lots and fed grass-legume mixed round bales. At the start of each trial period, BW and BCSs of horses were taken, hay cores were taken for nutritive analysis, and hay bales were weighed. Hay waste was collected daily, and when hay could no longer be consumed ad libitum, the remaining hay was removed from both pens (orts) and new bales were fed. Hay waste and orts were dried and daily dry matter intake was estimated as the difference between hay provided minus hay waste and orts during the trial period divided by the total BW of the pen. The average bale weight, forage nutritive value, BW, and BCS did not differ across treatment groups (P ≥ .05). However, the daily dry matter intake differed (P ≤ .05) at 2.31% BW for blanketed horses and 2.51% BW for nonblanketed horses. These results suggest blanketed horses conserve energy leading to decreased feed intake.