Crossley R E, Harlander-Matauschek A, DeVries T J
Department of Animal Biosciences, University of Guelph, 50 Stone Rd. East, Guelph, ON, N1G 2W1, Canada.
Department of Animal Biosciences, University of Guelph, 50 Stone Rd. East, Guelph, ON, N1G 2W1, Canada.
J Dairy Sci. 2017 May;100(5):3825-3838. doi: 10.3168/jds.2016-12108. Epub 2017 Mar 9.
The objective of this study was to investigate the effects of differing levels of competition for feed access on group-housed dairy cows, and on variations in behavior and productivity between individuals within each group. Eighteen lactating Holstein cows, averaging 77 ± 20 d in milk with a production of 46 ± 7 kg/d at the start of the trial, were divided into subgroups of 3 and fed a total mixed ration 3×/d. Groups were exposed to each of 3 competition levels: high (3 cows:1 feed bin), moderate (3 cows:2 feed bins), and low (3 cows:3 feed bins). Treatments were assigned in random order according to a modified Latin-square design, and each was applied for 10 d. Using an automated feed intake system, feeding behavior data (dry matter intake, feeding time, feeding rate, and meal patterns) were recorded for each cow on d 6 to 10 of each treatment period. Additional behavioral [sorting, rumination, competitive interactions (replacements), lying time] and production (milk yield and components) data were collected. Greater competition resulted in a reduction in feeding time (low = 202.6, moderate = 194.9, high = 183.6 min/d; SE = 8.84), and an increased rate of feed intake (low = 0.16, moderate = 0.18, high = 0.20 kg of dry matter/min; SE = 0.01), especially following fresh feed delivery and milking. Dry matter intake was similar across treatments (average of 29.1 kg/d). Meal length increased under high competition (low = 37.0, moderate = 36.6, high = 47.3 min/meal; SE = 5.05) due to greater non-feeding time within meals, which was approximately twice as long under high competition (low = 10.0, moderate = 10.8, high = 20.3 min/meal; SE = 3.24). Daily lying time (low = 10.2, moderate = 10.2, high = 9.5 h/d; SE = 0.51) and milk protein yield (low = 1.41, mod = 1.42, high = 1.36 kg/d; SE = 0.05) were reduced under high competition. Analysis of individual within-group variability, calculated as the daily standard deviation of each group, averaged across 5 recording days, revealed greater variability in feeding time, feeding rate, meal length, non-feeding time within meals, milk yield, milk fat composition (%), and milk fat component yield (kg/d) under high competition. These results suggest that at elevated competition levels, cows modify their feeding behavior to consume feed in a shorter period and devote a large portion of their mealtime toward waiting to gain feed access, resulting in reduced daily lying time. Furthermore, meal patterns and milk production vary greatly within groups of cows at high levels of competition for feed access.
本研究的目的是调查不同程度的采食竞争对群饲奶牛的影响，以及对每组内个体行为和生产性能差异的影响。18头泌乳期荷斯坦奶牛，试验开始时平均产奶77±20天，日产奶量46±7千克，被分成3头一组的亚组，每天饲喂3次全混合日粮。各组分别处于3种竞争水平：高（3头牛：1个饲料槽）、中（3头牛：2个饲料槽）和低（3头牛：3个饲料槽）。处理按照改良拉丁方设计随机分配，每种处理应用10天。使用自动采食量系统，在每个处理期的第6至10天记录每头奶牛的采食行为数据（干物质摄入量、采食时间、采食速率和采食模式）。还收集了其他行为数据[分群、反刍、竞争互动（替换）、躺卧时间]和生产数据（产奶量和成分）。竞争程度越高，采食时间减少（低=202.6，中=194.9，高=183.6分钟/天；标准误=8.84），采食速率增加（低=0.16，中=0.18，高=0.20千克干物质/分钟；标准误=0.01），尤其是在新鲜饲料投喂和挤奶后。各处理间干物质摄入量相似（平均29.1千克/天）。在高竞争水平下，采食餐次长度增加（低=37.0，中=36.6，高=47.3分钟/餐；标准误=5.05），这是由于餐内非采食时间增加，在高竞争水平下非采食时间约为低竞争水平下的两倍（低=10.0，中=10.8，高=20.3分钟/餐；标准误=3.24）。高竞争水平下，每日躺卧时间（低=10.2，中=10.2，高=9.5小时/天；标准误=0.51）和乳蛋白产量（低=1.41，中=1.42，高=1.36千克/天；标准误=0.05）降低。对组内个体变异性进行分析，计算为每组5个记录日的日均标准差，结果显示在高竞争水平下，采食时间、采食速率、餐次长度、餐内非采食时间、产奶量、乳脂肪成分（%）和乳脂肪成分产量（千克/天）的变异性更大。这些结果表明，在竞争水平升高时，奶牛会改变采食行为，在更短时间内采食饲料，并将大部分采食时间用于等待获取采食机会，导致每日躺卧时间减少。此外，在采食竞争水平较高时，奶牛群体内的采食模式和产奶量差异很大。
