Effekt av tilleggsfôr på atferd hos storfe på beite. | Effects of supplement feed on cattle behaviour on pasture

English. Genetics, supplement feed, environment, and management affect cattle behaviours and diurnalpatterns on pasture, thus reflecting individual and/or group difference in time budgets. Theaim of this study was to investigate effects of supplement feed on grazing behaviour anddistance travelled by Zebu heifers during mid-rainy season in Tanzania. 18 heifers aged 3-5years were assigned to one of three treatments: pasture only (PO), pasture plus supplement(PS), and supplement only (SO). Supplements were distributed twice daily before and afterpasture, and consisted of ad lib access to untreated straw plus concentrate (5 kg / heifer / day)for the PS group, and ad lib access to treated straw plus concentrate (5 kg / heifer / day) forthe SO group. The restricted pasture management of 8 hours daily grazing time (0900-1700)included the PO and PS groups only. For 11 consecutive days on pasture, behaviouralobservations, distance travelled, weather type, and temperature was recorded during two dailyobservation bouts from 0900-1200, and 1400-1700. Behavioural observations included scanintervals every 10 min, registering location on pasture according to a grid map, and activitywithin one of six behaviours: (1) grazing, (2) walking without grazing, (3) ruminating whilestanding, (4) ruminating while lying, (5) resting, and (6) other. Additionally, six days ofbehavioural observations during supplement feeding times were conducted. Mean initialbodyweights (BW) prior to trial was 229 ± 39 kg for all animals, and after one month on trialmean BW gains were 13.2 ± 4.2 kg, 31.3 ± 6.8 kg, and 23.2 ± 7.4 kg, for the PO, PS, and SOgroups, respectively.As predicted, providing heifers with supplement feed decreased time spent grazing (in % oftotal time) during morning (PO=88.4 ± 2.1, PS=78.5 ± 2.9, P ≤ 0.05) and afternoon (PO=72.1± 4.8, PS=60.3 ± 4.8, P=0.10) observation bouts. Thus, morning activity created significantdifferences in resting (PO=2.9 ± 1.3, PS=7.5 ± 1.7, P ≤ 0.05) and other behaviours (PO=2.2 ±0.6, PS=5.4 ± 0.7, P ≤ 0.01). During the afternoon, a further decline in time spent grazingsuccessively increased time spent resting (PO=7.7 ± 2.6, PS=11.5 ± 1.8, P=0.25) and otherbehaviours (PO=2.9 ± 0.5, PS=6.6 ± 1.2, P ≤ 0.05). Ruminating while standing had the largestincrease in percent of time from morning (PO=1.0 ± 0.6, PS=1.8 ± 0.6, P=0.40) to afternoon(PO=7.2 ± 2.5, PS=10.9 ± 2.9, P=0.34).Distances travelled remained equal between PO and PS groups on pasture, with slightlylonger distances travelled during morning (PO=692.9 ± 64.6 m, PS=643.3 ± 50.3 m, P=0.55)vthan afternoon (PO=600.4 ± 68.5 m, PS=595.5 ± 63.7 m, P=0.96) bouts. When blocked byweather categories, the PO group (1575.0 m) walked significantly farther than the PS group(1362.5 m) during overcast weather (P ≤ 0.05). In addition, the PS group consistently spentless time grazing than the PO group, and differences were significant in three of four weathercategories (mixed overcast: P=0.18, overcast: P ≤ 0.0001, mixed sunny: P ≤ 0.0001, andsunny: P ≤ 0.05).During supplement feeding, there were significant individual differences in time spent eatingconcentrate (P ≤ 0.01), walking/relocating (P ≤ 0.05), and eating straw (P ≤ 0.05) within thePS group, yet no individual differences were found in time spent grazing on pasture (P=0.54).

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