使用代乳自動餵飼系統對犢牛生長表現與健康狀況之影響

仔牛在離乳前的哺乳階段，為其一生中生長速率最快、飼料效率最高的時期，而仔牛的生長表現與健康狀況也與未來的泌乳量、牧場規模及穩定收入密切相關。在台灣的酪農場中，飼養頭數有逐漸增加的趨勢，但願意投入畜牧產業的勞力卻逐漸減少，因此需仰賴自動化的設備來解決勞力不足的問題。然而，大多數的酪農場仍採用仔牛單獨關欄、水桶飼養的傳統飼養模式，造成仔牛的活動空間受限與非符合仔牛自然行為的餵奶方式而出現異食癖等問題，導致仔牛生長表現不如預期，故如何提升仔牛的生長表現同時又能減少勞動力已經成為一項重要的議題。本試驗使用 20 頭荷蘭(Holstein-Friesian)仔牛，包含 7 頭仔公牛與 13 頭仔母牛，依據出生日期、性別、一週齡體重將仔牛於 7 日齡時平均分配於兩種欄位，分為對照組(採傳統飼養模式，單隻關欄，水桶餵奶)與實驗組(採自動餵乳系統餵奶，群體關欄)。每頭仔牛試驗為期七週(至 56 日齡)，對照組每日以水桶提供 7 公升牛奶，分早晚兩次供應，而實驗組每日則透過自動餵乳系統提供 7 公升牛奶，分三餐供應，每次最多可攝取 2.33 公升，兩組的教槽料於進入試驗時即供應，乾草(百慕達)於 14 日齡時開始供應，會視仔牛採食狀況做添加，水則採任食。檢測項目包含對照組與處理組 2~8 週齡之採食量、生長表現與行為表現，還有在仔牛 1、2 月齡時進行血液生化值測定，此外也記錄試驗期間仔牛的疾病治療狀況與疾病期間的行為變化。而在試驗結束後混入相同欄位時，進行後續的體重變化追蹤，以了解離乳前兩種飼養條件對仔牛後續生長表現的影響。結果顯示，使用自動餵乳系統的群飼仔牛在前兩週有較高的代乳攝入量，但在 8 週齡試驗結束時之體重與體測值(體高、臀高、胸寬、臀寬、胸圍、體長、前管圍)方面與對照組無差異，而在離乳後則是有較平穩的增重狀況。行為表現上，在前六週也有較高的站立時間、反芻時間，以及較少的躺臥時間。而在疾病評估方面，使用自動餵乳系統的群飼仔牛有較多的疾病狀況且有高的治療比例，但在血液生化值的各項檢測結果中，皆與對照組無差異，僅在白血球數量上有略高的趨勢但未達顯著。總結來說，以群體飼養搭配自動餵乳系統的餵奶方式對仔牛的生長表現無顯著影響，可能與本次試驗代乳的設限總量與次數有關，然而，卻有促進仔牛採食與鼓勵活動的潛力，還可降低勞動力與餵飼時間的成本。雖有較高的疾病發生風險，但若能多觀察仔牛與檢查自動餵乳系統與活動量偵測器所收集到的數據，儘早找出問題仔牛，給予治療，使其盡快恢復健康，勢必可增進仔牛的動物福利。

關鍵字

仔牛；自動餵乳系統；群飼；採食量；生長表現；行為；健康

並列摘要

The milk feeding stage before weaning is the period that calves have the fastest growth rate and highest feed efficiency in their lives. The growth performance and health status of calves are closely related to future milk production, farm size, and stable income. In Taiwan’s dairy farms, the herd scale is gradually increasing, but the labor willing to join the livestock industries is gradually decreasing. Therefore, it is necessary to rely on automatic equipment to solve the problem of labor shortage. However, most dairy farms still adopt the traditional calf feeding practice with individual pen and bucket feeding, which restricts the activity space and renders calves to drink milk in unnatural posture. As a result, abnormal behaviors occur and the growth performance of the calves is not as expected. Therefore, how to improve the growth performance of calves while reducing labor has become an important issue. Twenty Holstein-Friesian dairy calves (7 males and 13 females) were used in this experiment. At the age of 7 days, the calves were evenly allotted to two experimental groups according to the date of birth, gender, and 1 week old body weight. The calves assigned to the control group were fed milk replacer by bucket in individual pen, and the other calves assigned to the treatment group were fed milk replacer by automatic milk replacer feeding system (AMF) in group pen. All calves were on trial for seven weeks (up to 56 days of age). The control group was provided 7 liters of milk replacer daily in two meals by distributing in buckets in the morning and evening, while the treatment group was provided 7 liters of milk replacer daily through the AMF divided into three meals with a maximum milk intake of 2.33 liters each meal. A commercial starter and Bermuda grass hay was provided for ad libitum intake. Starter was begun to supply when calves entered the experiment, and hay was begun to supply at the age of 14 days with adjustment according to the daily intake condition. Fresh water was provided for ad libitum intake. The measurements included the feed intake, growth performance and behavior of calves at the age of 2-8 weeks, and the blood biochemical value at the age of 1 and 2 months. In addition, the disease treatment events of the calves during the experiment period and the behavior changes during the disease period were recorded. At the end of experiment, all calves were mixed into the same pen, and the follow-up weight change was tracked to understand the impact of the two feeding practices before weaning on the subsequent growth performance of the calves. The results showed that the group-raised calves using the AMF had a higher intake of milk replacer in the first two weeks. The calves at the 8-week-old had no significant difference between two groups in body weight and body frame measurements (withers height, thurl height, chest width, thurl width, chest girth, body length, shin circumference), but there was a stable weight gain in treatment group after weaning. In terms of behavior, group-fed calves also had higher active time, rumination time, and less inactive time in the first six weeks. In terms of disease assessment, the group-fed calves using the AMF had more disease conditions and more medical treatment. In blood biochemistry, there was no difference between two groups, only the number of white blood cells showed a slightly higher trend in group-fed calves. In summary, the group-fed method using AMF had no significant effect on the growth performance of the calves, which may be related to the fixed total amount and frequency of milk replacers settings in the present experiment. However, group-fed method has the potential to promote milk replacer intake and encourage activities for calves, also could reduce the cost of labor and feeding time, although there was a higher risk of disease. If we can observe the calves and check the data collected by the AMF and activity detector more often to find out the sick calves, treat and restore them to health as soon as possible, it may improve the welfare of calves.