Biomedical subjects

S L Kronberg

Publications and source records attributed to S L Kronberg.

5 recordsLinked to original sources

PubMed1999

Behavioral, nutritional, and toxicological responses of cattle to ensiled leafy spurge.

Yearling cattle (n = 25; 416.1 +/- 25.9 kg) were stratified by weight and gender across five groups. Group 1 (OAT) was offered oat/rape haylage (ORH) for ad libitum consumption during two daily feeding periods. Group 2 (SPURGE) was offered leafy spurge/grass haylage (LSGH) for ad libitum consumption during the same feeding periods. Group 3 was offered ORH in an amount equal to the average amount of LSGH consumed by SPURGE at the previous feeding. Group 4 (MIX) was offered LSGH mixed with ORH for ad libitum consumption during the two feeding periods. Group 5 (PAIR) received the equivalent amount of ORH consumed by MIX at the previous feeding. The DMI for OAT, SPURGE, and MIX were similar at the first feeding (P = .52). The SPURGE group consumed very little LSGH thereafter and was removed from the trial. The OAT and MIX groups consumed similar amounts of DM daily on d 1 to 4 when the ration offered to MIX was only 7% LSGH (P = .33). When LSGH made up > or = 21% of the mixture (d 7 to 32), the OAT group consumed more daily DM than did MIX (P < .05). The spurge/oatlage ration offered to MIX was less digestible than the oatlage-only ration offered to PAIR (P < or = .01). Even though blood chemistry did not indicate that LSGH consumption caused organ damage, its intake caused minor alterations (P < or = .05) in serum albumin, calcium, gamma glutamyltransferase, P, K, and urea nitrogen. No gross or microscopic lesions, infectious agents, or significant numbers of parasites were detected in any of the carcasses or tissues examined. The MIX group had diarrhea for much of the trial. In Trial 2, five yearling cattle were adapted to a mixture of 21% LSGH and 79% ORH. Then they were simultaneously offered three mixtures of spurge and oat haylages: 1) spurge ensiled with a microbial inoculant (LSGH); 2) spurge ensiled with the same inoculant and a cellulolytic/hemicellulolytic enzyme (ENZ); and 3) spurge ensiled with the same inoculant and molasses (MOL). The mixture with ENZ was preferred over those with MOL or LSGH (P < .001), but the amounts consumed were low and similar to those for LSGH-ORH in Trial 1 when amounts of ENZ and LSGH in the mixtures were similar. The ENZ mixture may have been more palatable than LSGH and MOL because it had less (P < .05) lactic acid, but intake of ENZ indicates that it had aversive characteristics, like LSGH. Ensiling leafy spurge did little, if anything, to improve its palatability to cattle.

Animal Husbandry↗

PubMed1997

Relationships between nutrition and foraging behavior of free-ranging sheep and goats.

Goats generally tolerate dry season forage conditions in northeastern Brazil's tropical deciduous woodland better than sheep do, but the mechanisms underlying sheep and goat response to wet and dry season conditions are not well understood. We evaluated aspects of nutrition and behavior of free-ranging sheep and goats in this woodland to improve our understanding of these mechanisms. Body weight changes, dietary botanical and chemical composition, and daily activities were measured for sheep and goats that foraged in this woodland during four defined periods of a year. Vegetation available to these animals was also measured. Although there was much less available vegetation during the wet season than during the dry season, body weights and dietary crude protein content of sheep and goats increased during the wet season and decreased during the dry season. During the four periods of the year, weight changes of sheep, and possibly those of goats, were positively related to the content of crude protein in their diets. Foraging times of sheep and goats were generally greater during the dry season than during the wet season and were positively related to available browse and inversely related to dietary crude protein content. Sheep and goats may have foraged longer during the dry periods because they were spending more time searching through the large quantity of low-quality vegetation for dietary items with relatively higher levels of crude protein.

Animal Nutritional Physiological Phenomena↗

PubMed1995

Abortifacient response and plasma vasoconstrictive activity after feeding needles from ponderosa pine trees to cattle and sheep.

Consumption of needles from Pinus ponderosa (PN) during late pregnancy causes cattle, but not sheep, to abort. This differential response may be caused by differences in ruminal microflora or postabsorptive metabolism. Pine needles were fed (2 kg.cow-1.d-1 or .4 kg.ewe-1.d-1) mixed with corn silage. In Exp. 1, cows were assigned at 250 d of pregnancy to feed treatments (T): 1) silage, 2) PN+silage, or 3) pretreated with sheep ruminal fluid and fed PN+silage. Interval to parturition was 34.3, 11.3, and 8.3 d for the T1, T2, and T3, respectively (T1 vs T2 + T3, P < .01; T2 vs T3, P > .5). Inoculation with sheep ruminal fluid did not alter activity of the abortifacient agent of PN. In Exp. 2, pregnant and nonpregnant ewes and cows were fed silage or PN mixed with silage, and plasma was analyzed for uterine vasoconstrictive activity in an in vitro placentome perfusion bioassay. Consumption of PN decreased interval to parturition in cattle (P < .01) but not in sheep (P > .5) and increased vasoconstrictive activity (P < .05) in plasma from nonpregnant and pregnant cows and ewes. The PN-fed ewes had a greater incidence of dead lambs at parturition (0/8 vs 5/8 for control vs PN-fed, P < .01). We conclude that pregnancy is not required for increased vasoconstrictive activity induced by pine needles, that sheep and cattle do not differ in ruminal metabolism of the abortifacient compounds in PN, and that species differences are subtle and due to postdigestive differences in response to the abortifacient agent.

Abortifacient Agents↗

PubMed1993

Feeding behavior of grazing ruminants experiencing stress.

The mechanisms underlying diet selection of ruminants are less studied than those for monogastrics. However, recent studies have shown that these mechanisms may be more similar in ruminants and monogastrics than previously believed. Food aversion learning is observed in both monogastrics and ruminants, and the hypothalamic-pituitary-adrenal axis appears to be involved in avoidance learning. Using leafy spurge (Euphorbia esula), an introduced weed whose expansion has costly ecological and economic implications in western North America, as a model for underconsumed plant species, we hypothesized that sheep experience increased cortisol levels when they first consume leafy spurge and that this may be related to their reluctance to graze it. We also hypothesized that preexposure to leafy spurge would attenuate the development of a spurge-based aversion. Correspondingly, we hypothesized that preexposed sheep would not experience increased blood cortisol levels with leafy spurge gavage during an aversion trial. None of our hypotheses were disproved by the experiments. Our results lend support to the hypothesis that stress is required for the development of conditioned taste aversions and extend it to ruminants. We suggest that activity of the hypothalamic-pituitary-adrenal axis is integral to food aversion learning in ruminants.

Animals↗

PubMed1993

Feed aversion learning in cattle with delayed negative consequences.

Two experiments were conducted to study the ingestive behavior of cattle when given a delayed dose of the aversive agent lithium chloride (LiCl) after eating a novel feed. In the first experiment, 20 calves were randomly divided into four groups (n = 5). The control group (G1) received 80 mg/kg BW of sodium chloride (NaCl) 4 h after eating a novel feed. Groups 2 (G2), 3 (G3), and 4 (G4) received 80 mg/kg of LiCl at 4, 8, and 12 h, respectively, after eating the novel feed. When calves were offered the novel feed on subsequent days, G2 and G3 ate less (P < .05) than G1. There was no difference (P > .05) in intakes between G1 and G4. In the second experiment, 15 calves were randomly divided into three groups (n = 5). The control group (G1) received 80 mg/kg BW of NaCl 12 h after eating a novel feed, whereas G2 and G3 received 80 and 160 mg/kg BW, respectively, of LiCl 12 h after eating the novel feed. When calves were offered the novel feed on subsequent days, G1 and G2 ate similar (P > .05) amounts, whereas G3 ate much less (P < .05) of it than the other groups. Cattle learned to avoid novel feeds even when they experienced negative postingestive consequences up to 12 h after they ate the feeds. The capacity for long-delay learning seems to be related to the severity of negative consequences experienced.

Animal Feed↗