Identifying factors which maximise the lambing performance of hoggets: a cross sectional study

AIM: To identity perceptions of farmers with respect to advantages of hogget lambing and to identify optimal management strategies for hogget lambing used in New Zealand.

METHODS: A questionnaire was sent to 1,038 sheep farmers in New Zealand who had indicated their hoggets would be lambing in 2002. Information was gathered on the practice of hogget lambing in New Zealand, in particular on the numbers and breeds of hoggets and rams used, selection criteria used for hoggets, use of teasers (vasectomised rams), length of mating period, use of mating crayons, vaccinations, medications and mineral supplements given, level of feed offered, use of pregnancy scanning, management during pregnancy and lambing, number of lambs present at docking, and shearing policies for hoggets. Farmers were also asked to indicate the relative importance of five stated reasons for choosing to have their hoggets mated in 2002.

RESULTS: A total of 629 (60.6%) responses were incorporated in the analysis, and the average percentage of hogget lambing was 60%. Use of vaccinations, length of the mating period, number of rams used, breed of hogget, weight at mating, management during lactation, and shearing policy were associated (p<0.05) with the lambing performance of hoggets, in the multivariate analysis.

CONCLUSIONS: This study indicated that to ensure high lambing percentages (LP) in hoggets in New Zealand, sheep farmers should: vaccinate hoggets against toxoplasmosis and campylobacteriosis; utilise a 40-day mating period; use 2.6–3.5% of rams during mating; incorporate Finn or East Friesian genetics; ensure liveweights at mating are as high as possible; manage single- and multiple-bearing/-rearing hoggets separately during the lambing and lactation periods; and shear hoggets pre-mating.     

Effects of L-carnitine on nitrogen retention and blood metabolites of growing steers and performance of finishing steers

Two experiments were conducted to evaluate L-carnitine supplementation to cattle fed grain-based diets. In Exp. 1, seven Angus-cross steers (216 kg) were used in a 7 x 4 incomplete Latin square experiment to evaluate the effects of supplemental L-carnitine on N balance and blood metabolites. Steers were fed a corn-based diet (17.5% CP) at 2.5% of BW. Treatments were 0, 0.25, 0.5, 1.0, 1.5, 2.0, and 3.0 g/d of supplemental carnitine. The 18-d periods included 13 d for adaptation and 5 d for collection of feces and urine. Blood was collected before feeding and 3 and 6 h after feeding on d 18 of each period. Dry matter intakes tended to be highest when 1.5 g/d of carnitine was supplied, but N retention was not affected by carnitine and averaged 29.3 g/d. Plasma carnitine concentrations and urinary excretion increased with increasing carnitine supply, indicating that at least some of the carnitine escaped ruminal degradation and was absorbed by the steers. Plasma concentrations of NEFA demonstrated a treatment x time interaction; they decreased linearly in response to carnitine before feeding but increased linearly in response to carnitine at 6 h after feeding. Serum insulin and plasma glucagon, IGF-I, cholesterol, triglyceride, and amino acids were not affected by carnitine. Plasma concentrations of glucose, glycerol, urea, and beta-hydroxybutyrate all were increased by some of the levels of carnitine supplementation, but results for these measurements did not follow easily described patterns and seemed to be related to differences in DMI. In Exp. 2, 95 crossbred steers (357 kg initial BW) were fed finishing diets (14.5% CP) for 129 d. Diets were based on steam-flaked corn and contained 6% alfalfa and 4% tallow. Feed intakes, gains, and feed efficiencies were not affected by supplementation with 2 g/d L-carnitine. However, steers receiving L-carnitine tended to have fatter carcasses, as indicated by tendencies (P < 0.2) for thicker backfat, higher marbling scores, and higher yield grades. In conclusion, carnitine supplementation did not alter lean deposition in growing steers but it did alter plasma NEFA concentrations of growing steers fed a corn-based diet and also seemed to increase fat deposition in finishing cattle.