Evaluation of the effects of nematode parasitism on grazing behaviour, herbage intake and growth in young grazing cattle

Parasitic nematodes, even in the absence of any clinical disease, can cause a reduction in voluntary feed intake in housed ruminants. This trial examined these effects on young cattle grazing pastures. Twenty dairy heifer calves, born in the previous autumn, were blocked according to liveweight and allocated to one of two groups: either untreated or dosed with an IVOMEC((R)) (ivermectin) SR Bolus 10 days prior to turnout on 1 May 1998. The groups grazed separately on two paddocks on predominately ryegrass swards. Liveweights were recorded every 28 days and faecal samples taken for worm egg counts at the same time.In mid-May and mid-July, for two 14-day periods, animals were paired within treatment groups and transferred to one of 10 replicate paddocks of similar sward height and herbage mass. Grazing behaviour and herbage intake were measured during these periods.In mid-May, 2 weeks after turnout, treated and untreated animals showed no difference in grazing behaviour or daily intake of grass. By mid-July, 10 weeks after turnout, the untreated heifers spent on average 105min less per day in grazing time and their daily herbage intake was 0.78kg dry matter (DM) per day lower than that of the treated animals. Residual sward height, mass and composition in the trial paddocks reflected these differences. There were no clinical signs of gastrointestinal parasitism in the untreated group up to this time; in July, the mean worm egg count in this group was 120 eggs per gram (e.p.g.) of faeces. Faecal samples from several untreated animals were positive for lungworm larvae by July, mild clinical signs of bronchitis were observed in two of these animals in mid-July. Over the period from turnout until mid-July, the untreated heifers showed a reduction in mean daily liveweight gain of 150g, compared to the treated animals.     

Parent volatiles in comet 9P/Tempel 1: before and after impact

We quantified eight parent volatiles (H2O, C2H6, HCN, CO, CH3OH, H2CO, C2H2, and CH4) in the Jupiter-family comet Tempel 1 using high-dispersion infrared spectroscopy in the wavelength range 2.8 to 5.0 micrometers. The abundance ratio for ethane was significantly higher after impact, whereas those for methanol and hydrogen cyanide were unchanged. The abundance ratios in the ejecta are similar to those for most Oort cloud comets, but methanol and acetylene are lower in Tempel 1 by a factor of about 2. These results suggest that the volatile ices in Tempel 1 and in most Oort cloud comets originated in a common region of the protoplanetary disk.     

Parasitoids (Hymenoptera, Ichneumonoidea) of Saproxylic beetles are affected by forest successional stage and dead wood characteristics in boreal spruce forest

The habitat requirements and effects of forest management on insects belonging to higher trophic levels are relatively unknown in forest ecosystems. We tested the effect of forest successional stage and dead wood characteristics on the saproxylic parasitoid (Hymenoptera, Ichneumonoidea) assemblage in boreal spruce-dominated forests in northern Sweden. Within each of nine areas, we selected three sites with different management histories: (1) a clear-cut (2) a mature managed forest and (3) an old-growth forest. Parasitoids were collected in 2003 using eclector traps mounted on fresh logs, which were either untreated (control), burned, inoculated with fungi, or naturally shaded, and on artificially-created snags.Both forest type and dead wood characteristics had a significant effect on parasitoid assemblages. Grouped idiobionts and some species, such as Bracon obscurator and Ontsira antica, preferred clear-cuts, while others, such as Cosmophorus regius (Hym., Braconidae) and other koinobionts, were associated with older successional forest stages. No single dead wood substrate was sufficient to support the entire community of parasitoids in any forest type, even when the regular host was present. In particular, snags hosted a different assemblage of species from other types of dead wood, with parasitoids of Tetropium spp. such as Rhimphoctona spp. (Hym., Ichneumonidae) and Helconidea dentator (Hym., Braconidae) being abundant. These results indicate that a diversity of dead wood habitats is necessary to support complete assemblages of beetle-associated parasitoids from early successional stages of dead wood and that parasitoids may be more sensitive to habitat change than their hosts.     

Feeding behavior and ruminal acidosis in beef cattle offered a total mixed ration or dietary components separately

Eighty continental crossbred beef heifers (414.9 ± 37.9 kg of BW), 16 of which were ruminally cannulated, were used in a 52-d experiment with a generalized randomized block design, to assess if self-selection of dietary ingredients modulates ruminal pH and improves rumen function of feedlot finishing cattle. Treatments were total mixed ration [TMR; 85% barley grain (BG), 10% corn silage (CS), 5% supplement]; or free-choice (self-selection; FC) diets of barley grain and corn silage (BGCS), barley grain and wheat distillers grain (BGDG), or corn silage and wheat distillers grain (CSDG). Heifers were housed in groups of 10 in 8 pens equipped with the GrowSafe System (Airdrie, AB, Canada) enabling feed intake and feeding behavior to be continuously monitored. Two cannulated heifers were randomly assigned to each pen and equipped with indwelling pH probes for continuous measurement of ruminal pH during 4 periods (d 1 to 4, d 7 to 14, d 21 to 28, and d 42 to 49). Rumen fluid samples were collected from cannulated heifers on d 7 and 42 before feed delivery, and on d 4 and 49 at 2 h post-feed delivery for determination of VFA. Heifers fed the TMR had shorter (P = 0.01) and smaller (P = 0.03) meals than those fed the FC diets. Cattle fed BGCS and BGDG increased (P < 0.01) intake of BG over time by up to 80 and 70%, respectively. Increased consumption of BG arose from an increase (P < 0.01) in eating rate over the same (P > 0.10) feeding time, which was accompanied by an increase (P < 0.05) in eating rate but a decrease (P < 0.05) in feeding time of either CS or DG. Even with increased BG consumption, ruminal pH and VFA profiles were not different (P > 0.10) among FC diets or compared with the TMR. Cattle fed FC CSDG consumed DG at 60% of dietary DM over the trial, resulting in greater (P < 0.05) mean ruminal pH and acetate-to-propionate ratio and less (P < 0.05) area under the curve than those given the other FC diets or the TMR. Finishing feedlot cattle fed FC diets containing BG self-regulate intake of diets that have a similar composition, intake level, and ruminal fermentation profile to those fed a TMR.     

Combinations of rendered protein meals for growing calves.

Complementary responses between rendered protein meals were investigated in this study. In a preliminary trial using 12 mature wethers in two replications, there was no difference (P greater than .20) in N digestibility between meat and bone meal (MBM; 96.7%), feather meal (FTH; 89.8%), and soybean meal (SBM; 98.7%). In a 112-d growth trial, individually fed calves (n = 120; 230 kg) received graded levels of FTH, MBM, 50:50 MBM-FTH (CP basis), or SBM with or without tryptophan (Trp) supplementation. Additions of Trp increased plasma Trp levels (P less than .05) but failed to improve efficiency of protein utilization (P greater than .35). Pooled results showed that this efficiency was greater (P less than .05) for FTH (1.47) than for MBM (1.04), FTH:MBM (.80), or SBM (.66). A trial was conducted to determine whether Trp addition reduces growth response to FTH:MBM (50:50) combinations. Calves (n = 230; 285 kg) were blocked by sex and weight into six replications and received FTH:MBM supplying 35% of the supplemental CP fed alone or with a high or low level of Trp supplement. Negative (urea only) and positive controls were included. Calves receiving FTH:MBM combinations gained faster (P less than .10) and were more efficient (P less than .10) than urea-supplemented calves. Performance was not altered by Trp addition. Calves (n = 120; 230 kg) were individually fed in two replications (43 or 48% CP MBM in Replications 1 and 2, respectively) of a growth trial to determine whether there was a complementary response between blood meal (BM) and MBM.(ABSTRACT TRUNCATED AT 250 WORDS)     

Heme binding by the serum proteins of fish]

Starch gel and disc electrophoretical results about heme binding of serum proteins of fishes (Pike, perch, bream) are reported on. Metheme albumin binding and a hemopexin polymorphism could be detected in all species of the fishes. The problems of differentiation between heme and hemoglobin binding are discussed.     

Restricting access time at pasture and time of grazing allocation for Holstein dairy cows: Ingestive behaviour,dry matter intake and milk production

The objective of this study was to assess the effects of restricting access time to pasture and time of grazing allocation on grazing behaviour, daily dry matter intake (DMI), rumen fermentation, milk production and composition in dairy cows. Twenty-one autumn-calving Holstein cows were assigned to one of the following 3 treatments: providing access to a daily strip of pasture for either 8 h between 07:00 and 15:00 h (T7–15), 4 h between 07:00 and 11:00 h (T7–11), or 4 h between 11:00 and 15:00 h (T11–15). The experimental period consisted of 3 weeks of adaptation and 6 weeks of measurements. Cows were offered a daily herbage allowance of 18 kg DM/cow to ground level, 6.1 kg DM/day of a ground sorghum grain-based supplement and 5.2 kg DM/day of maize silage. Milk yield was greater for cows with 8 h access time to the pasture (25.4 vs. 24.1 for 8 and 4 h access time, respectively). Milk yield was not different between cows that access early (T7–11) or late (T11–15) to the grazing session. Milk protein yield was greater for cows with 8 h access time (0.75 kg/d) vs. 4 h access time treatments (0.72 kg/d). Cows with late access time to grazing in the morning produce more protein (0.74 kg/d) than cows with early access to the pasture (0.70 kg/d). Duration of access had a significant effect on herbage DMI (8.3 vs. 6.6 kg/d, for 8 and 4 h access, respectively), but there was no significant effect of time of grazing allocation. Intakes of concentrate and maize silage DM did not differ between treatments.     

Value of sunflower seed in finishing diets of feedlot cattle

The value of sunflower seed (SS) in finishing diets was assessed in two feeding trials. In Exp. 1, 60 yearling steers (479 +/- 45 kg) were fed five diets (n = 12). A basal diet (DM basis) of 84.5% steam-rolled barley, 9% barley silage, and 6.5% supplement was fed as is (control), with all the silage replaced (DM basis) with rolled SS, or with grain:silage mix replaced with 9% whole SS, 14% whole SS, or 14% rolled SS. Liver, diaphragm, and brisket samples were obtained from each carcass. In Exp. 2, 120 yearling steers (354 +/- 25 kg) were fed corn- or barley-based diets containing no SS, high-linoleic acid SS, or high-oleic acid SS (a 2 x 3 factorial arrangement, n = 20). Whole SS was included at 10.8% in the corn-based and 14% in the barley-based diets (DM basis). In Exp. 1, feeding whole SS linearly increased DMI (P = 0.02), ADG (P = 0.01), and G:F (P = 0.01). Regression of ME against level of whole SS indicated that SS contained 4.4 to 5.9 Mcal ME/kg. Substituting whole for rolled SS did not significantly alter DMI, ADG, or G:F (8.55 vs. 8.30 kg/d; 1.36 vs. 1.31 kg; and 0.157 vs. 0.158, respectively). Replacing the silage with rolled SS had no effect on DMI (P = 0.91) but marginally enhanced ADG (P = 0.10) and improved G:F (P = 0.01). Dressing percent increased linearly (P = 0.08) with level of SS in the diet. Feeding SS decreased (P < 0.05) levels of 16:0 and 18:3 in both diaphragm and subcutaneous fats, and increased (P = 0.05) the prevalence of 18:1, 18:2, cis-9,trans-11-CLA and trans-10,cis-12-CLA in subcutaneous fat. In Exp. 2, barley diets supplemented with high-linoleic SS decreased DMI (P = 0.02) and ADG (P = 0.007) by steers throughout the trial, whereas no decrease was noted with corn (interaction P = 0.06 for DMI and P = 0.01 for ADG). With barley, high-linoleic SS decreased final live weight (554 vs. 592 kg; P = 0.01), carcass weight (329 vs. 346 kg; P = 0.06), and dressing percent (58.5 vs. 59.4%; P = 0.04). Steers fed high-linoleic SS plus barley had less (P < 0.05) backfat than those fed other SS diets. No adverse effects of SS on liver abscess incidence or meat quality were detected. Although they provide protein and fiber useful in formulating finishing diets for cattle, and did improve performance in Exp. 1, no benefit from substituting SS for grain and roughage was detected in Exp. 2. Because of unexplained inconsistencies between the two experiments, additional research is warranted to confirm the feeding value of SS in diets for feedlot cattle.