果皮在家禽饲料中的价值

发布单位:天津瑞孚农牧科技集团有限公司

查看次数:6164

时间:2019-11-29

最近爆发的非洲猪瘟对猪群造成了一定程度的损害,为了寻求其他可替代的肉类产品,全球家禽的需求量将会上升。对家禽产品的更高需求可能导致全球家禽价格上涨。为了维持全球家禽类价格,可替代/低成本的饲料原料将是维持家禽饲料压力的关键。考虑到人们对低抗营养因子的作物越来越感兴趣,外加先进的加工技术以及酶产品和抗营养结合剂在饲料市场的有效性,根茎类植物的外皮以及水果果肉可能是很有价值的饲料成分。
替代能量来源
家禽生产的预期增长直接影响到饲料的供应和价格。根据美国农业部(2015)的数据,从2005年到2015年,玉米价格上涨了71%。这表明了寻找可替代能量来源替代家禽饲料中常规使用的能源物质的重要性。食品和工业中根茎类植物和水果加工过程中产生了大量经济价值低的果皮和果肉加工剩余物,有效的利用这些剩余物对环境来说也是积极有利的。
富含淀粉的根茎类植物是重要的粮食作物,估计全球年产量为8.36亿吨(FAO,2013年),而果皮重量占到块茎重量的15%~20%;此外,大多数水果的果皮产量更高于根茎类植物,如木瓜和香蕉的果皮产量分别为31%和40%。此外,大量的水果可能会被浪费,约30~40%的香蕉由于缺陷和损坏而被淘汰(FAO,2012)。柑桔榨汁后留下的果肉残渣,占水果重量的50%~70%。

1 果皮作为饲料成分的优点
1.1 木薯
木薯皮的成分受品种、成熟期、农艺和环境等因素的影响。有研究报道称,木薯皮粉的蛋白质含量为30~60 g/kg,其中精氨酸含量较高;纤维含量更高(主要是NSPs), 为140~340 g/kg。木薯中主要的抗营养因子是氢氰酸,氰化物是高度热不稳定的,可以通过日晒降低到有毒水平以下。
1.2 山药
山药皮是一种能量来源,其代谢能量值为11.3~12.6 MJ/kg不等;蛋白质含量为91.4 ~ 127 g/kg。有研究报道表明,山药皮淀粉含量高,淀粉消化率高。
1.3 红薯
红薯皮能量高,蛋白质含量适中,粗纤维含量低。研究表明,其粗蛋白含量为36~46 g/kg,粗纤维为38~70 g/kg,代谢能值为11.25 MJ/kg。不同颜色的红薯是类胡萝卜素的良好来源,为可以使正常的鸡蛋和皮肤色素沉着对色素的需求减少补充量。也有相关报道描述了红薯皮中酚类化合物的研究。

1.4 柑橘

柑橘渣是柑橘汁工业的副产品,由柑橘果皮、果肉和种子按不同比例混合而成。柑橘品种和榨汁方法的不同影响着柑橘渣的成分,柑橘渣的能量值相对较高 (11.4 MJ/kg)和纤维含量高(123~135 g/kg 干物质),蛋白质含量在620~740 g/kg 干物质之间。在柑橘皮中发现了低浓度的蛋白酶抑制剂、植酸盐和单宁。果肉中含有大量的酚类化合物,具有很强的抗氧化能力。

1.5 香蕉

有研究显示香蕉的粗蛋白含量为5%或10%,在生和熟的香蕉皮中代谢能分别为11.6 ~ 14.0 MJ/Kg。果皮中含有儿茶酚,具有抗氧化、抗菌和降胆固醇的作用,单宁已被报道为香蕉皮中主要的抗营养因子。

1.6 甜菜渣

甜菜渣(SBP)也是另一种潜在的家禽饲料原料,但其用途受到低代谢能、高纤维和纤维的高持水能力的限制。研究发现SBP含有3 MJ ME/kg,9.6%粗蛋白,19%粗纤维 (主要为NSPs形式)。

1.7 木瓜

木瓜皮蛋白质与玉米相似,但纤维含量较高,脂肪含量较低。有研究报道,木瓜含有高浓度的蛋白水解酶(木瓜蛋白酶和木瓜凝乳蛋白酶)、维生素、矿物质和β-胡萝卜素。由于多酚类物质的存在,木瓜皮被报道具有驱虫剂、抗菌和抗球虫活性。抗营养因子包括单宁、生物碱、皂苷和黄酮类化合物。

2 果皮在肉鸡和蛋鸡日粮中的应用

有几项关于家禽果皮饲料喂养的研究,但建议各不相同。若干因素,包括果皮成分的差异(营养成分和抗营养组分)、加工方法、鸡只年龄和日粮成分,都可能影响家禽对果皮的利用。以下是来自不同研究的一些建议的摘要:

2.1 木薯皮

饲料中加入200g/kg木薯皮并不影响肉鸡的生长。也有研究称,与对照相比,饲喂500g/kg日粮干木薯皮的肉鸡体重增加和饲料效率有所提高;低氢氰酸含量(< 4mg kg)的木薯品种可以在不影响性能的情况下添加到500~600 g/kg。最近,有研究观察到,添加154g/kg日粮的木薯皮粉会对肉鸡的生产性能产生负面影响,但这可以通过添加脂肪和酶来克服。

2.2 山药皮

添加量为150g/kg山药皮时,肉鸡雏鸡的生长没有受到影响。有研究观察到250g/kg的山药皮粉添加量对肉鸡生长和胴体性状产生最佳效应;在育雏期和育成期分别推荐添加68和224 g/kg的山药红薯皮混合物(1:1)效果最佳。有报道称,山药-红薯皮混合物在肉鸡育雏期和育成期可替代日粮中15%和45%玉米,且对肉鸡生长、血液学指标和胴体测定无不良影响。

2.3 红薯皮

红薯皮能量高,蛋白质含量适中,粗纤维含量低。有研究者建议,不应将红薯皮粉添加到肉鸡育雏期饲料中,但可以在育成期饲粮中添加高达310g/kg;最近有学者建议150g/kg的添加量。

2.4 甜菜渣

2015年的一项研究发现,23g/kg是最适合肉鸡生长的添加量,而最近的一项试验发现,在肉鸡中补充酶可以使添加量达到75g/kg。

2.5 柑橘渣

报道称添加20g/kg的柑桔渣对肉鸡的生产性能和健康状况有改善作用。试验表明,在肉鸡日粮中添加50g/kg的柑橘皮,可使肉鸡的生长性能与玉米对照组相似。另一项试验报道,在肉鸡日粮中添加柑橘皮可达到79.2g/kg,且不影响肉鸡的生产性能。

2.6 香蕉皮
有研究推荐,在肉鸡日粮中添加100g/kg香蕉皮粉。此外,有学者观察到,同时添加酶补充物可使香蕉皮粉的使用达到340g/kg。此外,用干香蕉皮代替15%、30%或45%的黄玉米对生长性能、胴体特征和血液学参数没有影响。
2.7 木瓜皮
120g/kg木瓜皮粉对肉鸡生长无不良影响。在蛋鸡饲粮方面,木薯皮的来源、加工和鸡只年龄等因素都可能影响木薯皮的成分及其在饲粮中的使用。

3 果皮的未来
为满足世界对食品和工业用途日益增长的需求,世界大量生产块茎类和水果作物,这也表明,如果有适当得加工和储存技术,果皮是很容易获得的。果皮含有适量的营养成分,这使它们成为家禽饲料的潜在原料成分,将这些废弃物用于家禽饲料也可降低饲料成本和潜在的环境风险。再加上减少抗营养因子的加工技术的进步,将使果皮作为家禽饲料的价值更突出。
除了营养成分外,果皮还具有多种功能特性(抗氧化、抗菌、降胆固醇等),随着饲料添加剂(外源酶产品、氨基酸、抗氧化剂、抗营养结合剂)市场的不断扩大和饲料工业对植物生物制剂的研究兴趣的增加,果皮的应用前景更加广阔。

The value of peels in poultry diets
The recent outbreaks of African Swine Fever have damaged pig populations, especially in China. As a result, global poultry demand will rise as consumers seek out other meats as an alternative. The higher demand for poultry products might lead to a rise in global poultry prices during 2019. Less costly alternative feed ingredients will be crucial to sustain the pressure on poultry feedstuffs. Peels from roots and tubers as well as fruit pulps might be valuable feed ingredients, considering the increasing interest in breeding crops for low anti-nutritional factors, advanced processing technologies and availability of enzyme products and anti-nutrient binding agents in the feed market.
Alternative energy sources
The expected increase in poultry production has a direct effect on the availability and price of feed. From 2005 to 2015 the price of maize has increased by 71%, according to USDA (2015). This indicates the importance of alternative energy sources to replace the regularly used sources in poultry diets. The processing of roots and tubers and fruits for food and industrial uses results in the disposal of the low economic value residues in the form of peels and pulps. Utilisation of these residues as feedstuffs will also have a positive impact on the environment.
Starch-rich roots and tubers are important food crops with an estimated global annual production of 836 million tonnes (FAO, 2013). With peel weight accounting for 15–20% of the tuber weight one can estimate the amount of peels that can be produced from the processing of these crops. Peel yield is still higher in most fruits than roots and tubers. Peel yields of 31% and 40% have been reported in papaya and bananas, respectively. In addition, huge quantities of these fruits may be wasted, about 30–40% of bananas are rejected due to defects and damage (FAO, 2012). Citrus pulp, the residue left after juice extraction, represents up to 50–70% of the fruit weight.
The benefits of selected peels
Cassava – The composition of cassava peel is affected by several factors including cultivar, stage of maturity and agronomic practices and environmental factors. Adesehinwa et al. (2011) reported a protein content of cassava peel meal of 30–60 g/kg, with the protein content being high in arginine. The peel is high in fibre (mainly NSPs), 140 to 340 g/kg. The major anti-nutritional factor in cassava is hydrocyanic acid, however, cyanide is highly heat labile and can be reduced below toxic levels by sun-drying.
Yam – Yam peel is an average source of energy with metabolisable energy values ranging from 11.3 to 12.6 MJ/kg. The protein content ranges from 91.4 to 127 g/kg. High starch content and higher starch digestibility have been reported in yam peel.
Sweet potato – Sweet potato peel is high in energy, moderate in protein and low in crude fibre. Abdel- Hafeez et al. (2018) found the value of crude protein and crude fibre to be 36–46 g/kg and 38–70 g/kg, respectively, and a metabolisable energy of 11.25 MJ/kg. Coloured varieties of sweet potato are good sources of carotenoids, this can reduce the need of pigment supplements for normal egg and skin pigmentation. Phenolic compounds have also been reported in sweet potato peels.
Citrus – Citrus pulp is a by-product of the citrus juice industry consisting of a mixture of citrus peel, pulp and seeds in different proportions. The cultivar of citrus and differences in juice extraction methods affect the composition of citrus pulp. It has a relatively high energy (11.4 MJ/kg) content and high fibre ranging from 123-135 g/kg DM. Protein content ranges from 620-740 g/kg DM. Low concentrations of protease inhibitors, phytate and tannins have been reported in citrus peel. The pulp has high levels of phenolic compounds which demonstrate strong antioxidant capability.
Banana – Diarra et al. (2018) found CP of 5% while Blandon et al. (2015) found 10% CP. The metabolisable energy content of banana peel ranges from 11.6-14.0 MJ/Kg in the unripe and ripe peels, respectively. The peel contains catechins which possess antioxidant, antimicrobial and cholesterolemic activities. Tannins have been reported to be the major anti-nutritional factor in banana peel.
Sugar beet pulp – Sugar beet pulp (SBP) is also another potential feed ingredient for poultry feeding but its utilisation is limited by the low ME and high fibre content and high water-holding capacity of the fibre. Abdel- Hafeez et al. (2018) found a content of about 3 MJ ME/kg, 9.6% crude protein and 19% crude fibre (mainly in the form of NSPs).
Papaya – Papaya peel protein is like that of maize, but it is relatively high in fibre and low in fat. High concentrations of proteolytic enzyme (papain and chymopapain), vitamins, minerals and β-carotene have been reported in papaya. Due to presence of polyphenols, papaya peel is reported to have anthelmintic, antibacterial and anticoccidial activities. Anti- nutritional factors include tannins, alkaloids, saponins and flavonoids. Table 1 shows the nutrient composition of the peels drawn from different sources.
Peels in broiler and layer diets
There are several studies on the feeding of peel meals to poultry, but recommendations have been quite variable. Several factors including differences in the composition of the peel (nutrient and anti-nutrient contents), processing methods, age of birds and diet composition may all affect utilisation of peel meals by poultry. The following shows a summary of some recommendations from different studies:
Cassava peels
Inclusion of 200g of cassava peels/kg feed does not compromise growth in broilers. Dairo (2011) reported improved weight gain and feed efficiency in broilers fed 500g/kg dietary sun-dried cassava peel compared to control. In another study, Panigrahi (1996) suggested that low hydrocyanic acid (<4 mg kg) cassava cultivars can be included up to 500–600 g kg without affecting performance. more recently, dayal et al. (2018) observed that inclusion of sun-dried cassava peel meal at 154g kg diet adversely affected broiler performance but this was overcome by fat and enzyme supplementation.>
Yam peels
Broiler chick growth was not compromised when yam peel meal was included at 150g/kg diet. Ayodele (2011) observed that yam peel meal at 250g/kg diet was optimum for broiler growth and carcass traits. Diarra et al. (2012) recommended a yam-sweet potato peel mixture (1:1 wt/wt) at 68 and 224 g/kg diet for starter and finisher broilers, respectively. It was concluded that a yam-sweet potato peel mixture can replace maize up to 15 and 45% in broiler starter and finisher diets, respectively, without adverse effects on the growth, haematological profile and carcass measurements.
Sweet potato peels
Maphosa et al. (2003) advised that sweet potato peel meal should not be fed to broiler starter feeds but could be included up to 310g/kg diet in the finisher diets. More recently, 150g/kg diet was recommended by Abdel- Hafeez et al.
Sweet potato peel is high in energy, moderate in protein and low in crude fibre. Photo: Shutterstock
Sugar beet pulp
A 2015 study observed that 23g/kg was optimum for broiler growth and a more recent trial found that enzyme supplementation can allow the utilisation of the pulp up to 75g/kg diet in broilers.
Citrus pulp
Feeding 20g/kg citrus pulp meal diet was reported to improve the productivity and health of broiler chickens. Trials have shown that inclusion of 50g/kg citrus peel in diets of broiler chicks resulted in similar growth performance to the control group based on maize. Another trial reported that sweet orange peel can be included up to 79.2g/kg diet in broiler diet without adverse effects on performance.
Banana peel
Abel et al. (2015) recommended 100g/kg sun-dried banana peel meal in the diet for broilers. Additionally, Blandon et al. (2015) observed that enzyme supplementation allows the utilisation of air-dried banana peel meal up to 340g/kg. Furthermore, the effect of replacing 15, 30 or 45% of yellow corn with dried banana peels was not detrimental to growth performance, carcass characteristics and haematological parameters.
Papaya peel
Papaya peel meal at 120g/kg feed had no adverse effect on broiler growth. In terms of layer diets, several factors including the source of cassava peel, processing and age of birds may all affect the composition of cassava peel and its recommendations in the diet. Table 2 shows recommendations of selected peels in layer diets.
The future of peels
The huge world production of root/tuber and fruit crops to meet the increasing world demand for food and industrial uses indicates high availability of peels – if properly processed and stored. The utilisation of this waste in poultry feed would reduce feed cost and the potential environmental risks. Peels have moderate nutrient content, which makes them potential ingredients in poultry diets. This, coupled with the advances in processing technology to reduce anti-nutritional factors, would see an added value to peels for poultry feeding.
With the growing market and availability of feed additives (exogenous enzyme products, amino acids, antioxidants, anti-nutrients binding agents) and research interest into phytobiotics by the feed industry, the future use of peels is brighter. Less variable recommendations on inclusion rates would be better established. Besides the nutritive content, several functional properties (antioxidant, antimicrobial, cholesterolemic, etc.) are available in peels, this may further increase their use to produce consumer-friendly poultry products.