Food aversion learning: ability of lambs to distinguish safe from harmful foods

We studied the ability of lambs to select safe foods in the presence of harmful foods. In a series of feeding experiments, 3- to 6-mo-old lambs were offered a choice between 1) a familiar, safe and a novel, harmful food, 2) a novel, safe and a novel, harmful food and 3) a familiar, harmful and a novel, safe food. All harmful foods were palatable feeds that had been treated with lithium chloride (LiCl), a non-lethal gastrointestinal poison. When lambs ingested a meal composed of a novel food containing LiCl and a familiar, safe food, lambs subsequently avoided the novel food. Lambs avoided the novel food even when the familiar food contained LiCl. The response of lambs varied when lambs were given a choice between a novel, safe food and a novel food containing LiCl. Lambs either avoided the novel food containing LiCl and ingested the safe food or they limited their intake of both novel foods. Their response was dependent on the novelty of the food containing LiCl. When a novel, palatable food contained 2% LiCl, lambs always ate some of the food, even after experiencing illness from ingesting it. Lambs experienced with foods containing LiCl displayed greater food neophobia than lambs naive to LiCl-treated foods. Thus, novelty was the major criterion that lambs used to associate foods with gastrointestinal illness.     

Preference for flavored wheat straw by lambs conditioned with intraruminal infusions of starch administered at different times after straw ingestion

We hypothesized that the development and extinction of preferences for flavored foods paired with infusions of starch depends on the delay between food ingestion and starch administration and on the frequency of starch administration. To test this hypothesis, we divided 24 lambs into three groups of 8 lambs/group. On even days, half of the lambs were offered chopped wheat straw flavored with a distinctive flavor, whereas the other half received straw with a different flavor. Starch (12% of the daily DE required by the lambs) was infused into the rumen immediately after lambs began to eat straw in Group 1 (150 g starch), immediately after lambs began to eat straw (75 g) and 30 min later (75 g) in Group 2, and when straw refusals were collected 1 h after lambs began to eat straw in Group 3 (150 g). On odd days, the flavors were switched and infusions of starch were replaced with water. After 8 d of conditioning, starch infusions were suspended, and lambs were offered a choice of wheat straw with the two distinctive flavors. All lambs acquired strong preferences for flavored straw paired with starch (P< .001), but the delay between straw ingestion and starch infusion affected preferences (P<.05). Lambs that received starch 1 h after beginning to eat straw (Group 3) had lower preferences than lambs that received starch immediately after beginning to eat straw (Groups 1 and 2). Lambs that received two starch infusions (Group 2) did not show higher preferences for flavored straw than lambs that received only one starch infusion immediately after beginning to eat (Group 1). Lambs in our study retained preferences for at least 17 d when eating straw was no longer reinforced with starch (P<.001). However, preferences were less persistent for lambs that received starch immediately after beginning to eat straw (Group 1) than for lambs that received starch in two pulses (Group 2) or lambs that received starch 1 h after beginning to eat straw (Group 3). Collectively, our results support the hypothesis that the delay between food ingestion and starch administration affects food preferences of lambs. These findings suggest that manipulating the chemical characteristics of foods, which affects the kinetics of forage degradation in the rumen, can increase food preferences in ruminants.     

猪败血型链球菌病的诊疗报告

本文阐述了猪链球菌病的临床症状、实验室检验及防治方法，力求为科学防控猪链球菌病提供有益的探索和参考。     

Early experience with diverse foods increases intake of nonfamiliar flavors and feeds in sheep

This study determined whether early experiences by sheep with monotonous or diverse diets influence intake of unfamiliar flavors and feeds later in life. Thirty 2-mo-old lambs were randomly assigned to 3 treatment diets (n = 10): diverse (DIV), diverse with plant toxins (DIV+T), and monotonous (MON). Lambs in DIV received in 9 successive periods of exposure 4-way choice combinations of 2 foods high in energy and 2 foods high in protein from an array of 6 foods: 3 high in energy [beet pulp, oat grain, and a mix of milo:grape pomace (60:40)] and 3 high in digestible protein (DP) (soybean meal, alfalfa, corn gluten meal). Lambs in DIV+T received the same exposure as DIV, but 2 plant toxins, oxalic acid (1.5%) and quebracho tannins (10%), were randomly added to 2 of the feeds in each of the choice combinations. Lambs in MON received a monotonous balanced diet, made with a mixture of all 6 feeds detailed before. All treatments received their feed in 4 separate buckets. During exposure, treatments did not differ in total daily DMI (P = 0.31), but daily intake of ME was less (P < 0.02) and daily intake of DP was greater (P < 0.03) for lambs in DIV and DIV+T than for lambs in MON. Treatments did not differ in ADG or G:F (P > 0.05). After exposure, lambs were offered a familiar feed (wheat bran) containing novel flavors (maple, garlic, or bitter) and 2-way choices of novel feeds (fescue hay vs. corn distillers grains, rice vs. calf manna, and green peas vs. rolled oats). Intake of maple-flavored wheat bran tended (P = 0.08) to be greater for lambs in DIV than for lambs in DIV+T and MON. Intake of bitter-flavored and garlic-flavored wheat bran were greater (P = 0.03 and P = 0.04, respectively) for lambs in DIV and DIV+T than for lambs in MON. During 2-way choice trials, lambs in DIV, but not in DIV+T, showed greater intakes of fescue hay (P = 0.05) and rice (P = 0.04) than lambs in MON. Intake of green peas was greater (P = 0.03) for lambs in DIV and DIV+T than for lambs in MON. At the end of testing, lambs in DIV but not in DIV+T showed greater ADG than lambs in MON (P = 0.05). Thus, early exposure to diverse foods enhanced acceptance of novel flavors relative to early exposure to a monotonous ration. Early experience with diverse feeds plus plant toxins led to a less diverse diet than early experience with diverse feeds. Early exposure to diverse feeds may be beneficial in production systems that require rapid acceptance and high intake of unfamiliar feeds.     

The Effect of Sedation on Gastric Emptying of a Liquid Marker in Ponies

OBJECTIVE: The effect of sedation on gastric emptying was evaluated in six ponies by monitoring serum concentrations of acetaminophen (AP) after intragastric administration. EXPERIMENTAL DESIGN: Prospective randomized experimental study. ANIMALS: Six adult ponies, 135 to 275 kg. METHODS: Fifteen minutes after the intravenous administration of xylazine (1 mg/kg), butorphanol (0.05 mg/kg), acepromazine (0.05 mg/kg) or saline, ponies were given AP (20 mg/kg in 350 mL water) by stomach tube. Blood for AP analysis was collected at baseline and 15, 30, 45, 75, 90, 105, and 120 minutes after AP administration. The time (Tmax) to reach peak serum concentration (Cmax), and the area under the AP serum concentration versus time curve (AUC) were determined for each treatment group. RESULTS: Tmax was 31 mins in the control group, and this increased significantly (P<.05) after sedation. Cmax decreased (P<.05) after xylazine administration, and AUC decreased (P<.05) after acepromazine. CONCLUSIONS: This study indicated that sedation has a significant effect on the gastric emptying rate of a liquid in ponies.     

Supplemental polyethylene glycol affects intake of and preference for sericea lespedeza by cattle

We tested the hypothesis that supplemental polyethylene glycol (PEG), a polymer that neutralizes the effects of tannins, would increase intake and preference of cattle for fresh-cut sericea lespedeza (SL; Lespedeza cuneata), a legume with high concentrations of condensed tannins. Sixteen crossbred steers (initial BW of 249 +/- 6.6 kg) were randomly assigned to 2 treatments: 1) grain supplement with PEG (PEG-S) and 2) grain supplement without PEG (control). To assess intake, we conducted a trial with 6 sample periods, each 6 d in duration, with steers fed SL and prairie hay (PH) in separate meals. Steers were fasted overnight and fed their respective supplements (with and without PEG) at 0800 h. Animals were then offered fresh-cut SL from 1050 to 1550 h, PH was fed from 1600 to 2000 h, and they were without food from 2000 to 0800 h the next day. To assess preference, we conducted 1-d tests in which steers had simultaneous access to SL and PH on the day following periods 2 to 6. As with the intake experiment, steers were fasted overnight and fed their respective supplements at 0800 h, but from 1050 to 1250 h all steers had access to SL and PH simultaneously. We weighed steers before and at the completion of the study and calculated ADG. Steers treated with PEG consumed more SL per unit of BW than control steers in periods 2 to 6 (period x treatment interaction, P < 0.001). In contrast, controls consumed more PH than steers given PEG (period x treatment x day interaction, P = 0.009). The PEG-S steers consumed more total DM (SL + PH) than controls in periods 3, 5, and 6 but not in periods 1, 2, and 4 (period x treatment interaction, P = 0.004). Sericea lespedeza intake as a percentage of total DMI was greater for the PEG-S steers every day except d 1 and 2 of period 1 (period x treatment x day interaction, P = 0.03). Averaged across the 5 preference tests, PEG-S steers selected a greater proportion of SL than did control steers (39 vs. 9%), and the magnitude of the difference was greater in the later tests (test x treatment interaction, P = 0.004). The PEG-S steers had greater ADG than controls (0.44 vs. 0.24 kg/d; P = 0.005). Our results indicate PEG increases intake of and preference for SL and suggest that PEG supplementation of cattle may increase intake of SL and improve ADG in pastures that contain SL.     

Clearcutting Brazilian caatinga: assessment of a traditional forest grazing management practice

Clearcutting is a common practice for removing woody vegetation in the semiarid tropics of northeast Brazil. The prevalent belief is that clearing increases carrying capacity for livestock by increasing herbaceous vegetation, yet little empirical evidence exists to support or refute the contention. We investigated the implications to small ruminant nutrition of clearcutting in the semiarid tropics of northeast Brazil. We found that biomass of herbaceous species increased sixfold following cutting of trees, but much of this increase was in the form of poorly palatable stem. The large supply of leaf litter from woody species that was typical of uncleared areas during the dry season was replaced by persistent green foliage on coppicing trees the year following clearing. This green foliage may enhance the nutritional quality of the diets of sheep and goats foraging on cleared areas during the dry season.