保持?jǐn)嗄虝r(shí)大窩的仔豬的生長(zhǎng)性能(2)

牧童

3. Water intake

It is vitally important to encourage piglets to maintain fluid intake post-weaning. It can take more than a week after weaning for the pig to restore its daily fluid intake to the equivalent of that on the day prior to weaning. According to Fowler and Gill (1989) a suckling pig has equivalent water consumption prior to weaning of ~680ml; however, water intake is only ~290ml in the first day post-weaning and averages ~442ml in the first week after weaning. It is only in the second week post-weaning that water intake averages ~770ml/pig. An adequate supply of fresh potable water is essential where the aim is to maximise post-weaning growth rates. Restricted water flow can reduce feed intake and consequently ADG by 15 %, respectively (Toplis and Tibble, 1994; Table 4). Drinker position is critical, as consumption can be inhibited if they are placed at the incorrect height, angle or position within the pen. Recommendations for the use of bite drinkers and bowls are shown in Table 5. Bowl drinkers are now more common because they waste 30 % less water and it is easier for pigs to find the water source. However, bowl drinkers should be cleaned at regular intervals to ensure a supply of clean water. Push type bowl drinkers have minimal water waste compared to nipple drinkers and float type bowls drinkers (Torrey et al., 2008). Whatever type of drinker is used for weaned pigs, it is important to use the same type also in the farrowing house.

Table 4. Effect of water flow rate on post-weaning pig performance (Toplis and Tibble, 1994).

Table 5. Recommendations on drinkers for weaner pigs (Pedersen, 1999)

4. Push energy intake early post-weaning

Daily gain during the first week post-weaning has a positive relationship with pig weight at day 56 post-weaning and particularly so for light weaned pigs (Tokach et al., 1992). There is huge variation in pre-weaning growth rates of pigs. Edwards and Rooke (1999) reported a betweenfarm variation in post-weaning growth rates of 34 % and within-farm variation of 165 %, attributing most of this variation to differences in feed intake.

In Moorepark, average pre-weaning growth rates (birth to weaning at 26 days) of ~260 g/day have been seen (Lawlor, 2000). Maintaining this growth rate in the early post-weaning period is problematic and in practice, intake in the first few days after weaning is normally insufficient to cover even the maintenance requirement, much less to support pre-weaning rates of gain (Lawlor et al., 2002). As a consequence of this, there is often catabolism of fat as the pig strives to balance its energy requirement for maintenance. Another consequence is a reduction in villous height seen after weaning which affects nutrient digestion, thus prolonging the postweaning growth lag and affecting performance to slaughter.

Table 6 explores the average daily feed intake necessary for a range of weaning weights and a range of diets of differing energy density to maintain pre-weaning energy intake levels in the early post-weaning period. It is evident that, on a high health pig unit with good pre-weaning performance, if a starter diet of 16.5 MJDE/kg is provided then pigs would need to consume 420 to 464 g/day before pre-weaning energy intakes from milk are matched. This table also demonstrates that the necessary feed intake per pig is reduced when the energy density of the diet provided is increased.

Table 6. Calculation of feed intake required post-weaning to match pre-weaning energy intake

5. Post-weaning diet

5.1. Level of milk products

Dairy products, though expensive, are very important constituents of diets for pigs in the early post-weaning period due to their effectiveness in improving growth rate and feed efficiency at this time (Lawlor et al., 2005a). The time taken to reach target slaughter weight (~97kg) was reduced by 5 days by feeding a high dairy product starter and link in the post-weaning period compared with a low dairy product starter (Table 8; Lawlor et al., 2003b). In addition to this, mortality, incidence of scour and veterinary interventions are all likely to be reduced while management is made easier when a high dairy product post-weaning diet is offered. However, economics (diet cost and pig price) will dictate the degree of complexity of the diet and its duration of feeding in the commercial situation (Lawlor et al., 2003b).

Including lactose as a carbohydrate source in the diet at levels even as high as 320 to 470 g/kg, increases post-weaning daily gain in weaned pigs. Dried whey contains 650 to 750 g/kg lactose and so it is the most widely used lactose source in starter diets. Crystalline lactose or de-proteinised whey can be used as lactose sources as long as they are of good quality. Skim milk powder is also commonly used in post-weaning diets but is not as critical in the diet as lactose and there is little benefit from substituting casein for soy protein sources for more than 2 weeks after weaning.

5.2. Cooking cereals

When cereals are included in diets for newly weaned pigs they have often been subjected to some form of heat processing. This is generally done to make the carbohydrate fraction of the cereal more available for enzyme digestion in the gut. This is particularly important in newly weaned pigs because of their initially low levels of starch-degrading enzymes. Increased starch availability is normally measured in the laboratory as an increase in the gelatinised starch content in a sample (Table 7).

Steam flaking is a relatively gentle heating process when compared with extrusion, expansion or micronization and is less likely to have negative consequences (formation of enzyme resistant starch and maillard reaction products, heat damage to amino acids). Steam flaking maize and wheat effectively increased the level of gelatinized starch in both maize and wheat (Table 7) but did not benefit post-weaning or lifetime pig performance. The response to inclusion of steam flaked maize and wheat in the post-weaning diet was not influenced by weaning age, weaning weight , level of dairy products in the diet (Lawlor et al., 2003a ;Table 8) or the sequence of feeding raw or uncooked cereals during the post-weaning period (Lawlor et al., 2003b). It is therefore difficult to justify the increased food cost associated with the process. Although we did not investigate the inclusion of barley in post-weaning diets, others found a 14% increase in average daily gain when the barley component of a post-weaning diet was extruded. This is most likely due to the higher fibre content in the barley.

Table 7. Starch and gelatinised starch values for wheat and maize used in experimental diets (Lawlor et al. 2003b)

Table 8. The effect of cooking maize and wheat (un-cooked or cooked) and level of dairy product (high or low) on pig performance from weaning to slaughter (Lawlor et al., 2003b)

Cereals are frequently thoroughly screened and cleaned in advance of any cooking process and these processes alone are beneficial in terms of reducing their microbial load and improving growth performance. Responses to cooking maize and wheat, in particular, are very variable in the literature and it is possible that where responses are seen that it may be due at least in part to a decontamination effect. Therefore, if raw cereals are to be used in post-weaning diets then quality well screened grains with a low microbial load should always be used.

3.飲水量

仔豬斷奶時(shí)維持液體攝取量極其重要。斷奶后恢復(fù)每天液體攝取量到斷奶前水平需要一周多時(shí)間。根據(jù)Fower 和Gill（1989）研究，乳豬斷奶前的飲水量約680ml；斷奶第一天的飲水量?jī)H僅約290ml；斷奶后第一周平均442ml。斷奶后第二周飲水量平均每只仔豬770ml。提供足夠清新的水是很重要的，目的是使斷奶后增長(zhǎng)率達(dá)到最高。限制水流量使采食量減少，結(jié)果平均日增重下降15%（Toplis和Tibble，1994，表四）。飲水器位置是關(guān)鍵的，如果是一個(gè)不正確的高度，角度，方位或死角的位置，就會(huì)限制仔豬飲水量。推薦的鴨嘴式飲水器和滾球式飲水器給出于表五。滾球式更常用，因?yàn)橄啾戎滤梢詼p少浪費(fèi)30%的水。對(duì)于豬來說更容易發(fā)現(xiàn)水資源。而且，滾球式飲水器應(yīng)該每隔一段時(shí)間清洗，確保有大量的清潔水。碗式飲水器與乳頭式飲水器相比浪費(fèi)水較少（Torney等2008）。斷奶仔豬無論使用哪種類型的飲水方式，都應(yīng)該在產(chǎn)房里用同種類型的飲水器。

         表四 斷奶仔豬性能受水流量的影響(Toplis和Tibble，1994)

                                                                                

                      水流率（ml/分鐘）

                                                                                         

                      175              350           450           700

                                                                                      

飲水時(shí)間（min）    4.46               2.97           2.93            2.32                        

飲水量（ml/day）   780                1040          1320            1630

采食量  (g/day)     303                323           341             347

平均日增重（g/day）210                235            250            247

飼料轉(zhuǎn)化率         1.48                1.39           1.37           1.42

                                                                                 

表五  斷奶仔豬飲水器的說明（Pederson 1999）

                                                                                 

豬的重量             飲水器類型              與地面的高度          流水量

（kg）                                           (cm)              （I/min）

5                      Bite                       30                  30

15                     Bite                       45                  45

25                     Bite                       55                  55

7-30                   Bowl                       5-10                5-10

                                                                                    

4.斷奶豬早期的能量攝入

     斷奶仔豬第一周的日增重與豬斷奶后56天重量呈正相關(guān)特別是對(duì)輕的斷奶仔豬來說更明顯。(Tokach等1992)。在豬斷奶前的生長(zhǎng)速度變異很大。Edwards 和Rooke(1999)報(bào)道，不同豬場(chǎng)仔豬斷奶后增長(zhǎng)率變異約34%，農(nóng)場(chǎng)內(nèi)變異是165%，這個(gè)變異主要是采食量不同造成的。

在摩爾莊園，是26日齡斷奶，段奶前的增長(zhǎng)率是平均每天260g（Lawlor 2000），在斷奶后的前幾天要保持這個(gè)增長(zhǎng)率是很有問題的。實(shí)踐中，在斷奶后前幾天的采食量通常不足，甚至不能滿足維持需要，更不用說去支持增重（Lawlor等，2002）。結(jié)果，豬為了維持需要，經(jīng)常分解代謝體脂肪以平衡能量缺口。另一個(gè)結(jié)果是在斷奶后腸絨毛長(zhǎng)度減少，它影響營(yíng)養(yǎng)的消化吸收，這會(huì)延遲斷奶后增長(zhǎng)，這個(gè)影響可以一直到上市屠宰。

表六是為了維持能量攝取水平，在豬的斷奶前期去探索一系列不同斷奶體重的豬和一系列采食不同能量密度飼料的豬它們的平均每天采食量分別是多少。顯然，在斷奶前有一個(gè)好性能的健康的豬，如果一開始提供的飼料能量密度是每千克165兆焦，豬將每天需要消耗420g到464g的飼料，這與斷奶前所采食的母乳所含的能量攝入量一致。這個(gè)表也證明了提供飼料的能量密度增加，使得每只豬的采食量減少。

表六 與斷奶前能量攝取量相當(dāng)?shù)臄嗄毯蟛墒沉坑?jì)算

                                                                                          

采食量                                                                                 

斷奶日齡        26天

初生重          1.5千克

                                                                                      

斷奶重      平均日增重   兆焦          克/每天   克/每天     克/每天   克/每天                                                           

6.7          200          5.6            384         359        338      318

7.4          225          6.3            432         404        380      358

8.0          250          7.0            480         449        422      398                                                   

8.7          275          7.7            528         494        464      438                                                

9.3          300          8.4            576         539        506      498

10.0         325          9.1            624         584        549      517

10.6         350          9.8            672         629        591      557

                                                                                 

5.斷奶后的日糧

5.1乳制品的水平

乳制品雖然很貴，但是在斷奶后前期仔豬日糧成份是非常重要的，因?yàn)樗芴岣咴鲩L(zhǎng)率和改善飼料轉(zhuǎn)化率。在斷奶后，攝取高乳制品日糧的豬和攝取低乳制品日糧的豬相比，實(shí)際屠宰日齡可減少5天。此外，給仔豬提供高乳制品日糧時(shí)，斷奶仔豬死亡率，腹瀉發(fā)生率，獸醫(yī)參與次數(shù)都下降，當(dāng)然管理起來就更容易了。然而，在商業(yè)盈利情況，經(jīng)濟(jì)（飼料成本和豬的價(jià)格）將決定日糧的復(fù)雜程度和飼料使用的持續(xù)時(shí)間。

仔豬斷奶后，作為碳水化合物來源的乳糖在飼料中的含量高達(dá)每千克320g到470g，可以增加日增重。每千克乳清粉含有650g到750g的乳糖，因此，它是使用最廣的豬日糧中乳糖的來源。質(zhì)量好的精制乳糖或低蛋白乳糖可以被用作乳糖。在斷奶仔豬的日糧中，脫脂奶粉也很通用，但是它在日糧中作為乳糖不是關(guān)鍵的，它替代酪蛋白收益很少，在斷奶后替代大豆蛋白資源不能超過兩周。

5.2谷物的加工

     斷奶仔豬日糧中的谷物經(jīng)常先經(jīng)過加熱處理，這個(gè)做法使得谷物中部分碳水化合物更容易被腸道中的酶消化。這個(gè)對(duì)剛剛斷奶的豬特別重要，因?yàn)樗鼈冏畛醯慕到饷杆胶艿?。在?shí)驗(yàn)中，通常通過測(cè)定可溶性淀粉的含量增加量來衡量樣品中糊化淀粉的增加量。

  蒸汽壓片與壓榨、膨脹或者微粉化相比是一個(gè)比較溫和的熱處理，很少有負(fù)面影響（形成抗性淀粉、美拉德反應(yīng)和氨基酸的熱損害）。蒸汽壓片處理的玉米和小麥有效地增加了玉米和小麥的糊化淀粉水平（表7），但是它對(duì)斷奶豬或豬整個(gè)生長(zhǎng)過程的性能沒有受益。蒸汽壓片玉米和小麥在斷奶后仔豬日糧中使用的結(jié)果，不受斷奶日齡、斷奶體重、日糧中乳制品含量水平的影響（勞勒等人。，2003a；表8），也不受谷物飼用先后或熱處理影響（勞勒等人，2003。）。因此，很難證明增加的食物成本與這個(gè)加工過程有關(guān)。雖然我們沒有研究斷奶后日糧中大麥的影響，但是有報(bào)道說，斷奶后日糧中使用壓片大麥，平均日增重增加了14%。這很可能是由于大麥的高纖維含量。

表七 實(shí)驗(yàn)日糧中玉米和小麥的淀粉和糊化淀粉值（Lawlor等，2003）

                                                                                      

                   大麥           蒸汽處理的大麥      玉米       蒸汽處理的玉米

                                                                                       

淀粉（g/kg）       609                 624             654           644

糊化淀粉*           0.215               0.781            0.265         0.840

                                                                                               

注：*占淀粉總量的比例

表8是否熱處理玉米和小麥（未加工或加工）和乳制品的水平（高或低）對(duì)豬性能的影響（Lawlor 等2003）

                                                                                          

                                                        方差分析意義

程序                未煮熟        煮熟          未煮熟          煮熟    C+  DP*  C×DP**

乳制品水平           高            高             低              低

                                                                                               

豬重（kg）

斷奶                 7.4           7.5           7.4              7.5       0.1

26天 1）               19.1          20.0          18.5             18.5       0.5

125天2)               96.5          97.1          96.0             95.7       1.6

增長(zhǎng)性能

平均日采食量         571          583           576             578       16.9

0到26天1)

平均日增重           439          468           419             410       19.0    *

0到26天24

飼料轉(zhuǎn)化效率         1.36         1.27           1.39             1.43      0.06    +

0到26天 3)

                                                                                    

1)烹飪的影響，2)乳制品水平影響，3)烹飪和乳制品水平的相互影響，斷奶后天數(shù)。 <0.10, <0.05.

按照減少微生物和提高增長(zhǎng)性能的原則，任何加工過程和單獨(dú)加工過程前對(duì)谷物頻繁徹底地篩選和清潔是獲益的。在文獻(xiàn)中，特別是加工玉米和小麥的報(bào)道結(jié)果幻化很大，它至少部分被認(rèn)為是有去污作用。因此，在斷奶仔豬日糧中應(yīng)該總是使用被篩選過的質(zhì)量好的低微生物負(fù)載的谷物。