Buse K K, Kononoff P J
Department of Animal Science, University of Nebraska-Lincoln, Lincoln, NE 68503.
JDS Commun. 2024 Oct 29;6(2):223-226. doi: 10.3168/jdsc.2024-0653. eCollection 2025 Mar.
Forages comprise a large portion of dairy cattle rations, and quality can have a large influence on feed intake and milk production. Although factors like particle size, fiber content, and digestibility affect it, palatability can also play a role in feed intake. The objective of this study was to conduct an experiment to evaluate the effect of relative feed value (RFV) on feed preference. A taste preference sequential elimination experiment using 16 lactating Jersey cows (210 ± 4 DIM, 27.4 ± 3.24 kg/d milk yield, 19.6 ± 1.52 kg/d DMI; ± SD) was conducted to test this objective. Reduced-lignin alfalfa hay diets with a high RFV (213; HIRFV), mid RFV (163; MDRFV), and low RFV (94; LORFV) were compared with a control smooth brome grass hay (75 RFV; Brome). Cows were offered 0.45 kg of each alfalfa treatment and 0.23 kg of the hay treatment in a randomized arrangement within the feed bunk for 1 h or until the feed was fully consumed or consumed in the greatest amount. Feeds were offered for 9 d with all treatments offered the first 4 d. The most preferred feed was then removed, and the remaining 3 feeds were offered for 3 d. The process was repeated for the last 2 d. Feed preference was ranked from 1 to 4 with 1 being the most preferred and 4 the least; this was in the order they were removed. The rankings of each treatment for each cow were summed and averaged. The probability of a treatment being chosen first was determined using the Plackett-Luce model. The preference ranking of HIRFV was highest (1.06 ± 0.25), followed by LORFV (2.56 ± 0.63), MDRFV (2.75 ± 0.58), and Brome (3.25 ± 0.93). The probability of HIRFV being selected first is 95.7% ± 0.79%, whereas the probabilities of LORFV, MDRFV, and Brome being selected first are 2.09% ± 0.38%, 1.70% ± 0.38%, and 0.55% ± 0.46%, respectively. These results support the notion that higher quality alfalfa hay is preferred by cows. The secondary preference of LORFV could be associated with the presence of byproducts of Maillard reactions, which would lower the RFV while providing more favorable flavors than were present in MDRFV and Brome.
粗饲料在奶牛日粮中占很大比例，其质量对采食量和产奶量有很大影响。虽然粒度、纤维含量和消化率等因素会对其产生影响，但适口性在采食量方面也会发挥作用。本研究的目的是进行一项实验，以评估相对饲料价值（RFV）对饲料偏好的影响。使用16头泌乳泽西奶牛（210±4天泌乳天数，日产奶量27.4±3.24千克，日干物质采食量19.6±1.52千克；±标准差）进行了一项味觉偏好顺序消除实验，以验证这一目的。将高RFV（213；高RFV苜蓿干草日粮）、中RFV（163；中RFV苜蓿干草日粮）和低RFV（94；低RFV苜蓿干草日粮）的低木质素苜蓿干草日粮与对照无芒雀麦干草（RFV为75；雀麦干草）进行比较。在饲槽内以随机排列的方式，给奶牛提供每种苜蓿处理0.45千克和干草处理0.23千克，持续1小时，或直到饲料完全消耗或消耗到最大量。所有处理在前4天提供饲料，共提供9天。然后去除最受喜爱的饲料，对剩余的3种饲料再提供3天。在最后2天重复这一过程。饲料偏好从1到4进行排名，1为最喜爱，4为最不喜爱；排名顺序即为饲料被去除的顺序。对每头奶牛每种处理的排名进行求和并求平均值。使用Plackett-Luce模型确定一种处理被首先选择的概率。高RFV苜蓿干草日粮的偏好排名最高（1.06±0.25），其次是低RFV苜蓿干草日粮（2.56±0.63）、中RFV苜蓿干草日粮（2.75±0.58）和雀麦干草（3.25±0.93）。高RFV苜蓿干草日粮被首先选择的概率为95.7%±0.79%，而低RFV苜蓿干草日粮、中RFV苜蓿干草日粮和雀麦干草被首先选择的概率分别为2.09%±0.38%、1.70%±0.38%和0.55%±0.46%。这些结果支持了奶牛更喜欢高质量苜蓿干草的观点。低RFV苜蓿干草日粮的次优偏好可能与美拉德反应副产物的存在有关，这些副产物会降低RFV，同时提供比中RFV苜蓿干草日粮和雀麦干草更宜人的风味。
