保持?jǐn)嗄虝r大窩的仔豬的生長性能(3)

牧童

5.3. Diet Acidification

Early weaned pigs produce insufficient levels of gastric acid which can result in a high stomach pH. As a result, the digestion of nutrients, especially protein is reduced. Moreover, high pH is favourable for the proliferation of diarrhoea-causing micro-organisms in the weaned pig. The use of organic acids has been suggested as a means of lowering gastric acidity in weaned pigs and has been reported to improve growth performance. The benefits that arise from feeding organic acids include an inhibitory effect on pathogenic bacteria, increased amino acid and energy digestibility and an increase in nitrogen retention. The response to organic acids was previously found to be greatest in diets with low levels of dairy products. Dairy products contain lactose which can be fermented to lactic acid thus reducing gut pH. In addition, milk proteins are much more easily digested than vegetable proteins in the immature gut. The response to diet acidification might be expected to be reduced when provided in post-weaning diets to pigs that were provided with creep feed prior to weaning as creep feeding of suckling pigs is thought to benefit post-weaning pig performance by stimulating gastric acid production and enzyme secretion.

5.3  飼料酸化

早期斷奶仔豬產(chǎn)生胃酸使胃pH值高，由于水平不足，營養(yǎng)物質(zhì)的消化不足，尤其是蛋白質(zhì)消化不良。 然而，高pH值有利于斷奶仔豬腸道內(nèi)微生物繁殖，導(dǎo)致腹瀉。建議使用有機酸以降低斷奶仔豬胃的酸度，據(jù)報道這樣可以改善生長性能。從喂養(yǎng)有機酸產(chǎn)生的效益包括對病原菌的抑制作用，增加氨基酸和能量的消化率和氮潴留增加。 以前就已經(jīng)發(fā)現(xiàn)在日糧中含低水平乳制品時有機酸的反應(yīng)最大。乳制品中含有的乳糖可發(fā)酵產(chǎn)生乳酸，降低腸道pH值。此外，乳制品中的蛋白質(zhì)在未成熟腸道中比植物蛋白更容易消化。當(dāng)給斷奶前的仔豬采用漸變方式飼喂?jié)u變飼料后，仔豬斷奶后添加日糧酸化劑的效果可能會降低。斷奶前采用漸變飼喂方式可刺激胃酸和消化酶的分泌，促進斷奶后仔豬的生長。

Unexpectedly, Lawlor et al. (2005a) found that the response to a dietary acid was not influenced by the level of dairy product in the diet or whether pigs had or had not been creep fed while suckling the sow. Feed intake in one experiment was increased by ~32% in week 1 and by 11% over the first 3 weeks after weaning due to the dietary addition of fumaric acid. This increase in feed intake translated into a ~20% increase in growth rate in the first 3 weeks post-weaning. However, the response to diet acidification was not always consistent between experiments with a response to fumaric acid seen in 2 of the 3 experiments reported and the magnitude of the response varied greatly between the two experiments where a positive response was found. Similar results were found in later work (Lawlor et al., 2006). It was thought that microbial challenge during the post-weaning period has a major influence on the response to fumaric acid supplementation.

沒想到，勞勒等人（2005）發(fā)現(xiàn)，對日糧酸的反應(yīng)并不受哺乳期飼料是否有乳制品及其水平的影響。在一個實驗中，由于在飼料中添加富馬酸，在斷奶后第一周采食量量增加32%，前三周采食量增加11%。前三周采食量的增加轉(zhuǎn)化為前3周的生長速度提高20%。然而，在三個添加富馬酸的試驗中有2個報道不一致，所以斷奶仔豬日糧中添加富馬酸的反應(yīng)并不總是一致的。后來的研究也發(fā)現(xiàn)了類似的結(jié)果（勞勒等，2006）。所以認(rèn)為，斷奶后微生物挑戰(zhàn)對添加富馬酸的效果有主要影響。

Table 9. Effect of pre-weaning creep feeding on response of weaned pigs to dietary fumaric acid (Lawlor et al 2005a)

       表9斷奶前料過渡對斷奶仔豬日糧富馬酸反應(yīng)的影響（勞勒等人，2005）

                                                        標(biāo)準(zhǔn)誤差       F檢驗

蠕變                      否      否       是       是              添加富馬酸

富馬酸（富馬酸；克/千克） 0       20       0        20

豬體重（千克）

斷奶                     6.1    6.1      6.2      6.0       0.31         

結(jié)果                    12.1    12.9     11.9     13.6      0.67       **

采食量（克/天）

第一周                  194    233      180      260        19.0       ***

第二周                  528    550      533      623        46.0      

第三周                  658    696      667      711        43.7

總量                    466    500      466      535        30.3       *

日增重（克/天）

總量                    289    320      273      358         23.6      **

斷奶后微生物挑戰(zhàn)對添加富馬酸的效果有主要影響。

An alternative approach to diet acidification, which can yield similar benefits, is to formulate post-weaning diets to have a low acid binding capacity. Acid binding capacity can be defined as the amount of acid in milliequivalents (meq) of Hydrochloric acid required to lower the pH of 1kg of feed sample to (a) pH 4.0 (ABC-4) and (b) pH 3.0 (ABC-3) (Lawlor et al 2005b). The lower the acid-binding capacity of the feed, the lower the amount of gastric acid that is required to lower its pH and create an acidic environment in the stomach, which is beneficial to pig health and digestion. Lawlor et al. (2005b) published a data set of acid-binding capacity values for a wide range of feed ingredients. There is great variation between ingredients with regard to acid-binding capacity values. For this reason, complete post-weaning diets can be formulated to have a low acid-binding capacity by selection of ingredients from this dataset with low acid-binding capacity and by using the acid-binding capacity value for each ingredient in the diet formulation matrix. Such diets can be used when a high gastric pH is likely to be a problem (e.g., at weaning) and as an effective alternative to diet acidification. When such diets were formulated by reducing calcium and phosphorus content in the diet formulation, feed intake in the first week after weaning was increased by 17% (Lawlor et al., 2006). This is the time where we need to increase feed intake as it has such an influence on subsequent growth performance.

日糧酸化的另一種方法可以產(chǎn)生類似的效益，這個方法就是制定斷奶后的日糧配方時使之具有較低的酸結(jié)合力。酸結(jié)合能力可以定義為，為降低一千克飼料樣品的PH到（a）pH 4（abc-4）和（b）pH 3（abc-3）所需的鹽酸的毫克當(dāng)量（勞勒等人，2005）。飼料的酸結(jié)合能力越低，為降低胃中飼料的PH一創(chuàng)建胃中的酸環(huán)境所需要的胃酸就越少，這有利于豬的健康和消化。勞勒等人（2005b）公布了一組范圍廣泛的飼料原料的酸結(jié)合力值。就酸結(jié)合力值而言，不同飼料原料之間的變異很大。因為這個原因，在設(shè)計斷奶后仔豬日糧時，根據(jù)這祖酸結(jié)合力數(shù)據(jù)選擇原料，使用每一種飼料原料的酸結(jié)合力設(shè)計飼料配方，可以配合出酸結(jié)合力低的斷奶后配合飼料。如果存在高胃PH問題（例如斷奶時），就可以用這種日糧，這是日糧酸化的一種有效替代方法。通過減少飼料配方中鈣和磷的含量設(shè)計出這種日糧時，斷奶后第一周的采食量增加了17%（勞勒等人，2006）。這個時候需要增加采食量，因為這時的采食量影響后續(xù)生長性能。

5.4. Probiotics

Probiotics are ‘live microorganisms which when administered in adequate amounts confer a health benefit on the host’ (FAO/WHO, 2001). They offer potential as an alternative to antibiotics for pigs, both as a means of controlling enteric pathogens and improving growth performance. Their possible modes of action include modulation of the immune system, competitive exclusion of pathogens in the gut and antimicrobial production. Prieto et al. (2014) evaluated the safety and efficacy of a marine-derived Bacillus pumilus strain for use as an infeed probiotic in newly weaned pigs. The B. pumilus used was pre-screened and selected for its ability to inhibit porcine pathogenic E. coli (Prieto et al., 2013). The Bacillus strain was administered to weaned pigs fed a non-medicated diet and compared to a negative control treatment without antibiotic or pharmacological levels of zinc oxide (non-medicated treatment) and a positive control treatment containing apramycin and pharmacological levels of zinc oxide (medicated treatment). The study herd was at the time experiencing oedema disease during the post-weaning period. The B. pumilus strain decreased ileal E. coli counts in a manner similar to the medicated treatment but without the reduction in growth performance (Table 10) and possible liver toxicity found with the medicated treatment (Prieto et al., 2014).

益生菌是“活的微生物，當(dāng)給予足夠量的時候，就能對機體產(chǎn)生益處（FAO/WHO，2001）”。他們用于豬，具有替代抗生素的潛力，無論是作為控制腸道致病菌的手段還是提高豬的生長性能。其可能的作用方式包括免疫系統(tǒng)的調(diào)制，在腸道內(nèi)與病原菌的競爭排斥。普列托等人。（2014）評估了一個來自海洋的短小芽孢桿菌菌株作為益生菌在斷奶仔豬料的安全性和使用效能。使用的B. pumilus是預(yù)篩選的，并且選擇培育了其抑制豬致病性大腸桿菌的能力（普列托等人，2013）。把該菌株用于飼喂斷奶仔豬，這些仔豬使用無藥日糧，一個負(fù)的對照祖使用無抗生素或藥物治療劑量的氧化鋅（非藥物處理組），一個正的對照處理含安普霉素和氧化鋅藥理水平（藥物處理組）。研究群在斷奶后出現(xiàn)水腫病。B. pumilus菌株降低了回腸大腸桿菌計數(shù)，在某種方式看類似于藥物處理，但沒有生長性能下降（表10），并且藥物處理組發(fā)現(xiàn)了可能有肝毒性（普列托等人.，2014）。

Table 10. Effect of feeding non-medicated, medicated or B. pumilus treatments for 22 days on post-weaning pig growth performance1,2 (Prieto et al., 2014)

表10.非藥物處理、藥物處理22天或短小芽孢桿菌處理對斷奶豬生長性能的影響1,2（普列托等，2014）

            

                      非藥物處理  藥物處理 短小芽孢桿菌處理   標(biāo)準(zhǔn)誤差    P值

_______________________________________________________________________           

第0天體重3（千克）   8.7       8.6         8.8          0.26      0.38

第22天體重（千克）  18.1      17.6        18.7          0.35      0.07

平均日采食量4（克/天）471      458         475           12.6      0.53

平均日增重5（克/天） 427      405         455           15.7      0.07

飼料轉(zhuǎn)化率6        1.11ab       1.14a        1.05b          0.023      0.04

1 平均值及其標(biāo)準(zhǔn)誤差。2同一行數(shù)字中，上標(biāo)字母不同的數(shù)字表示有顯著差異（P＜0.05）3BW=體重 4ADFI=平均日采食量，斷奶至22天后。5ADG=平均日增重，斷奶至22天后。6FCR=飼料轉(zhuǎn)化率（平均日采食量/ 平均日增重）斷奶至22天后。

Casey et al. (2007) investigated the effects of oral treatment of pigs with a mixture of five lactic acid bacteria probiotic strains, on both clinical and microbiological signs of Salmonella Typhimurium infection. Following probiotic administration for 6 days, animals were challenged orally with S. Typhimurium and monitored for 23 days post-infection. Animals treated with probiotic showed reduced incidence, severity, and duration of diarrhea, gained weight at a faster rate than control pigs, and had reduced fecal shedding of Salmonella

凱西等（2007）研究了用五株乳酸菌益生菌合劑口服處理的影響，考察臨床和沙門氏菌感染微生物的跡象。益生菌處理6天后，動物口服鼠傷寒沙門菌，感染后23天檢測。用益生菌處理的動物表現(xiàn)出腹瀉發(fā)病率極度降低且發(fā)生拉稀的程度也很弱，體重增加的速度比對照豬快，并減少了糞便中的沙門氏菌

5.6. Prebiotics

Prebiotics, like probiotics, are used as a strategy to influence the composition of the gastrointestinal microflora towards a more favorable balance, by reducing the amount of harmful/pathogenic species and promoting the growth of species thought to have beneficial effects on host health (O’Sullivan et al., 2010). A prebiotic is “a selectively fermented ingredient that allows specific changes, both in the composition and/or activity of the gastrointestinal microflora that confers benefits upon the host wellbeing and health”. Prebiotics are resistant to digestion in the upper gut (i.e. resistant to acid and enzymes), a selective substrate for the growth of beneficial bacteria and able to induce luminal or systemic effects that are beneficial to host health. To date only inulin, oligofructose, galactooligosaccharides and lactulose are considered true prebiotics; however, other potential sources of prebiotics such as seaweed-derived compounds are currently being explored (O’Sullivan et al., 2010).

5.6 益生元

益生元，與益生菌相似，可以作為影響胃腸道微生物區(qū)系組成的策略，使之向著更加有益的方向平衡，作用途徑是減少有害病原菌種類數(shù)量，促進對宿主健康有益的微生物物種生長(奧沙利文等，2010)。益生元是“選擇性發(fā)酵成分，其允許發(fā)生特定變化，包括胃腸道微生物的組成和活性兩種變化，這些變化有益于宿主生存和健康”。益生元在上部腸道抗消化（即耐酸和酶），是有益于有益菌生長的物質(zhì)，這些有益菌有利于宿主健康。到目前為止只有菊粉，低聚果糖，低聚半乳糖和乳果糖被認(rèn)為是真正的益生元；然而，其他潛在的益生元如海藻衍生的化合物目前正在探索（奧沙利文等人.，2010）.