Energy Requirements of Tan Sheep during Non-Pregnancy Period

MA Jiayin; LUO Dike; HE Ximeng; LIANG Xuhui; KOU Qifang; NIU Wenzhi; YANG Yuxin

doi:10.12418/CJAN2024.495

Chinese Journal of Animal Nutrition >

2024 , Vol. 36 >Issue 9: 5828 - 5836

DOI: https://doi.org/10.12418/CJAN2024.495

RESEARCH PAPER

Energy Requirements of Tan Sheep during Non-Pregnancy Period

MA Jiayin ^,¹^,² ,
LUO Dike ¹ ,
HE Ximeng ¹ ,
LIANG Xuhui ¹ ,
KOU Qifang ³ ,
NIU Wenzhi ³ ,
YANG Yuxin ^,¹^,^*

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¹ College of Animal Science and Technology, Northwest A&F University, Yangling 712100, China
² Wuzhong Animal Disease Control and Prevention Center, Wuzhong 751100, China
³ Wuzhong Hongsipu District Tianyuan Well-Bred Sheep Breeding Co., Ltd., Wuzhong 751900, China

^* associate professor, E-mail: yxyang@nwafu.edu.cn

Received date: 2024-02-28

Online published: 2024-09-08

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Abstract

This experiment was conducted to study the energy metabolism rule and requirements of Tan sheep during non-pregnancy period, and to provide a theoretical basis for the construction of scientific feeding system. A total of 48 Tan sheep with similar body weight of (33.79±1.33) kg and good body condition during non-pregnancy period were randomly divided into 4 groups with 4 replicates per group and 3 sheep per replicate. Sheep in the four groups were fed diets with digestible energy of 6.69 (group Ⅰ), 7.29 (group Ⅱ), 7.97 (group Ⅲ) and 8.82 MJ/kg (group Ⅳ), respectively. The pre-trial period lasted for 7 days and the experimental period lasted for 30 days. The results showed as follows: 1) the average daily gain (ADG) of Tan sheep was increased with dietary energy level increasing, and the ADG in group Ⅳ was extremely significantly higher than that in the other groups (P<0.01), the ADG in group Ⅲ was extremely significantly higher than that in group Ⅰ (P<0.01), and the ADG in group Ⅱ was significantly higher than that in group Ⅰ (P<0.05). The dry matter intake (DMI) in group Ⅰ was significantly higher than that in group Ⅲ (P<0.05), but there was no significant difference in DMI among the other groups (P>0.05). 2) The digestible energy intake and metabolizable energy intake of Tan sheep were increased with dietary energy level increasing, the digestible energy intake in group Ⅳ was extremely significantly higher than that in groups Ⅰ and Ⅱ (P<0.01), and significantly higher than that in group Ⅲ (P<0.05); the metabolizable energy intake in group Ⅳ was extremely significantly higher than that in the other three groups (P<0.01), and the metabolizable energy intake in group Ⅲ was significantly higher than that in group Ⅰ (P<0.05). 3) The gross energy digestibility and gross energy metabolic rate of Tan sheep during non-pregnancy period were 52.42% to 59.85% and 43.14% to 51.36%, respectively. 4) The regression equations of digestible energy requirement and metabolizable energy requirement with metabolic body weight (W^0.75) and ADG for Tan sheep during non-pregnancy period were as follows: digestible energy requirement (MJ/d)=0.527 2W^0.75+0.040ADG (R²=0.897, P<0.01); metabolizable energy requirement (MJ/d)=0.401 6W^0.75+0.040ADG (R²=0.942, P<0.01). According to the regression model, the metabolizable energy maintenance requirement for Tan sheep during non-pregnancy period is 401.6 kJ/kg W^0.75, and the metabolizable energy requirement is 400.0 kJ for every 100 g daily gain.

Key words： Tan sheep; non-pregnancy period; energy requirements; energy digestion and metabolism

Cite this article

MA Jiayin , LUO Dike , HE Ximeng , LIANG Xuhui , KOU Qifang , NIU Wenzhi , YANG Yuxin . Energy Requirements of Tan Sheep during Non-Pregnancy Period[J]. Chinese Journal of Animal Nutrition, 2024 , 36(9) : 5828 -5836 . DOI: 10.12418/CJAN2024.495

在肉羊产业养殖规模化、管理标准化、经营集约化进程中,饲养标准的建立是产业发展的基本要求^[1]。近年来,在肉羊养殖过程中主要以NRC(2007)^[2]、《肉羊营养需要量》(NY/T 816—2021)为饲养标准进行参照。但在实际应用的过程中,因我国地域辽阔,肉羊品种地域特征明显,肉羊营养需要量存在差异,导致肉羊生产性能不能充分发挥。研究发现,羊生长期的维持净能(NEm)需要量在0.267~0.298 MJ/kg W^0.75^{[3⇓-^[5]]},高于NRC(2007)推荐的0.234 MJ/kg W^0.75。而能量作为生命活动开展的基础,动物摄入的能量主要用于自身维持需要和满足生产环节^[6],且受生理阶段、环境、性别以及年龄等因素的影响,因此是制约生产性能发挥的重要指标。

滩羊作为我国优秀的肉裘兼用型地方品种羊,具有肉质鲜嫩多汁、无膻味、脂肪分布均匀以及裘皮洁白悦目、毛毡紧实、轻巧保暖等特点^[7]。近年来,宁夏发挥滩羊品种资源和地理环境优势,致力于建设核心产区,滩羊养殖规模逐年扩大^[8],但滩羊饲料利用率低^[9],且当地饲草品质和产量不佳^[10],限制了滩羊产业的发展。空怀期是动物体况恢复的关键时期,其健康状态影响后期发情和配种效果,然而关于滩羊空怀期能量需要量的研究较少。因此,研究滩羊空怀期能量需要量对生产实践中提高饲料转化效率、促进动物生长和繁殖性能发挥以及提高基础母羊利用率等具有重要意义。本研究旨在研究滩羊空怀期能量代谢规律和需要量,为建设科学饲喂体系提供参考依据。

1 材料与方法

1.1 试验设计

本试验选取48只体重[(33.79±1.33) kg]接近、体况良好、1~2胎次的空怀期滩羊,随机分为4组,每组4个重复,每个重复3只羊。4组试验羊分别饲喂消化能为6.69(Ⅰ组)、7.29(Ⅱ组)、7.97(Ⅲ组)和8.82 MJ/kg(Ⅳ组)的饲粮。预试期7 d,正试期30 d。

1.2 试验饲粮

本试验所用饲粮参考《肉羊营养需要量》(NY/T 816—2021)进行配制,各组饲粮除消化能外,其他营养水平均保持一致。将饲粮加工调制成全价颗粒饲料进行饲喂,饲粮组成及营养水平见表1。

表1 饲粮组成及营养水平(干物质基础)

Table 1 Composition and nutrient levels of diets (DM basis) %

项目 Items	组别Groups
项目 Items	Ⅰ	Ⅱ	Ⅲ	Ⅳ
原料Ingredients
玉米Corn		15.02	26.71	29.21
豆粕Soybean meal	6.50		0.96	5.00
菜籽粕Rapeseed meal		7.00
麸皮Wheat bran	3.81	2.01	5.68
稻草Rice straw				45.00
苜蓿Alfalfa			10.51	10.32
玉米秸秆Corn stalk	83.65	69.97	50.14	1.05
大豆油Soybean oil				3.00
磷酸氢钙CaHPO₄	0.54	0.50	0.50	0.92
氯化钠NaCl	0.50	0.50	0.50	0.50
预混料Premix¹⁾	5.00	5.00	5.00	5.00
合计Total	100.00	100.00	100.00	100.00
营养水平Nutrient levels²⁾
消化能DE/(MJ/kg)	6.69	7.29	7.97	8.82
粗蛋白质CP	6.85	6.51	6.70	6.68
钙Ca	0.48	0.46	0.48	0.48
磷P	0.36	0.36	0.36	0.36

	1)每千克预混料含有 One kilogram of the premix contained the following:VA 280 000 IU,VD₃ 30 000 IU,VE 2 400 IU,Cu 0.33 g,Fe 1.75 g,Zn 1.4 mg,Mn 1.4 g,I 15 mg,Se 5 mg,Co 10 mg。
	2)消化能和粗蛋白质为实测值,其他为计算值。DE and CP were measured values, while the others were calculated values.

1.3 饲养管理

本试验在西北农林科技大学实践基地吴忠市红寺堡区天源农牧业科技开发有限公司进行。试验开始前,对羊舍进行为期7 d的改造及全面消毒,包括圈舍、料槽、饮水盆、饲喂器具及代谢笼等。随后,将试验羊按照试验分组引入相应圈舍。试验过程中,于每日08:00和17:00进行饲喂,试验羊自由采食,并根据采食情况及时调整饲喂量。收集每组饲粮和剩余料用于后期测定,统计饲喂量和剩料量,计算每天主要营养物质的实际摄入量。

1.4 消化代谢试验

正试期第21~30天,从每个试验组的4个重复中各挑选1只羊,在代谢笼中开展10 d的消化代谢试验。其中,前7 d为预试期,后3 d为收粪期,收集试验羊全部粪便和尿液样品,并统计相应数据。

1.5 样品采集

收集试验羊全部的粪便和尿液样品,每日根据排粪和排尿总量,分别采集5%和10%样品进行留样,并加入2%硫酸(H₂SO₄)溶液进行固氮处理(添加量每10 g粪样添加5 mL的H₂SO₄溶液)。试验结束后,将3 d的粪便和尿液样品分别混合并进行标注,保存在-20 ℃待测。

1.6 测定指标及方法

1.6.1 平均日增重

正试期开始的第1天和结束后第1天,于08:00空腹情况下称量试验羊体重,并做好记录。根据试验天数,计算平均日增重,计算公式为:

平均日增重(g/d)=(末重-初重)/试验天数。

1.6.2 常规营养成分

饲粮、粪便和尿液样品中干物质和粗蛋白质(CP)含量分别参照GB/T 6435—2014和GB/T 6432—2018测定;能量参照《饲料分析及饲料质量检测技术》^[11]中方法测定;钙和磷含量参照《肉羊营养需要量》(NY/T 816—2021)计算。

1.6.3 饲粮能量消化代谢指标

饲粮能量消化代谢指标根据以下公式计算:

消化能=总能-粪能;

代谢能=总能-粪能-尿能-甲烷能;

总能消化率(%)=100×消化能/总能;

总能代谢率(%)=100×代谢能/总能;

消化能代谢率(%)=100×代谢能/消化能。

式中:甲烷能采用Blaxter等^[12]的方法推算求得,甲烷能(%总能)=3.67+0.062×总能消化率。

1.6.4 能量摄入量

消化能和代谢能摄入量分别根据试验期采集量和消化代谢试验结果,按照以下公式进行计算:

消化能摄入量(MJ/d)=试验期饲粮

平均每日实际摄入量×饲粮中的总能×

母羊对饲粮的总能消化率;

代谢能摄入量(MJ/d)=试验期饲粮平均

每日实际摄入量×饲粮中的总能×

母羊对饲粮的总能代谢率。

1.7 数据统计分析

试验数据采用Excel进行初步整理,并采用SPSS 18.0软件进行单因素方差分析(one-way ANOVA),差异显著者采用Duncan氏法进行多重比较,P<0.05表示差异显著,P<0.01表示差异极显著,结果用“平均值±标准差”形式表示。

2 结果

2.1 饲粮能量水平对空怀期滩羊能量消化代谢的影响

由表2可知,尿能随饲粮能量水平的提高而降低,但各组之间无显著差异(P>0.05);甲烷能、总能消化率、总能代谢率以及消化能代谢率均随饲粮能量水平的提高呈现逐渐提高的变化规律,而总能和粪能未呈现出同样规律。具体而言,Ⅳ组总能显著高于其他各组(P<0.05),且其他各组间无显著差异(P>0.05);Ⅰ组粪能最高,显著高于Ⅲ组(P<0.05),与其他2组无显著差异(P>0.05);而Ⅳ组甲烷能最高,极显著高于Ⅰ组(P<0.01),显著高于Ⅱ组和Ⅲ组(P<0.05)。各组总能消化率为52.42%~59.85%,其中Ⅰ组总能消化率极显著低于Ⅳ组(P<0.01),显著低于Ⅲ组(P<0.05);各组总能代谢率为43.14%~51.36%,其中Ⅰ组最低,极显著低于Ⅲ组和Ⅳ组(P<0.01),显著低于Ⅱ组(P<0.05);各组消化能代谢率为82.23%~85.77%,其中Ⅰ组最低,显著低于Ⅲ组和Ⅳ组(P<0.05)。

表2 饲粮能量水平对空怀期滩羊能量消化代谢的影响

Table 2 Effects of dietary energy level on energy digestion and metabolism of Tan sheep during non-pregnancy period

项目 Items	组别Groups
项目 Items	Ⅰ	Ⅱ	Ⅲ	Ⅳ
总能GE/(MJ/d)	20.56±1.30^b	20.41±0.28^b	20.60±1.14^b	22.31±0.86^a
粪能FE/(MJ/d)	9.80±1.10^a	8.94±0.28^ab	8.50±0.53^b	8.93±0.66^ab
尿能UE/(MJ/d)	0.48±0.24	0.32±0.10	0.31±0.21	0.25±0.08
甲烷能E_CH4/(MJ/d)	1.42±0.07^Bb	1.46±0.04^ABb	1.51±0.10^ABb	1.65±0.12^Aa
总能消化率DE/GE/%	52.42±2.72^Bb	56.21±1.61^ABab	58.72±2.09^ABa	59.85±4.54^Aa
总能代谢率ME/GE/%	43.14±1.96^Bb	47.48±1.66^ABa	49.94±2.13^Aa	51.36±4.44^Aa
消化能代谢率ME/DE/%	82.23±2.05^b	84.45±0.97^ab	85.04±1.67^a	85.77±1.11^a

	同行数据肩标不同大写字母表示差异极显著(P<0.01),不同小写字母表示差异显著(P<0.05),相同小写字母或无字母表示差异不显著(P>0.05)。
	In the same row, values with different capital letter superscripts mean extremely significant difference (P<0.01), and with different small letter superscripts mean significant difference (P<0.05), while with the same small letter or no letter superscripts mean no significant difference (P>0.05).

2.2 饲粮能量水平对空怀期滩羊能量摄入量和平均日增重的影响

由表3可知,各组之间滩羊初重和末重均无显著差异(P>0.05);Ⅰ组干物质采食量最高,显著高于与Ⅲ组(P<0.05),与其他2组无显著差异(P>0.05)。各组能量摄入量中,消化能和代谢能摄入量与饲粮能量水平呈正相关,其中Ⅳ组总能摄入量组最高,显著高于Ⅱ组和Ⅲ组(P<0.05),与Ⅰ组无显著差异(P>0.05);Ⅳ组消化能摄入量组极显著高于Ⅰ组和Ⅱ组(P<0.01),显著高于Ⅲ组(P<0.05);Ⅳ组代谢能摄入量最高,极显著高于其他各组(P<0.01),且Ⅲ组代谢能摄入量显著高于Ⅰ组(P<0.05)。滩羊平均日增重与消化能和代谢能摄入量呈正相关,其中Ⅳ组平均日增重极显著高于其他各组(P<0.01),且Ⅲ组极显著高于Ⅰ组(P<0.01),Ⅱ组显著高于Ⅰ组(P<0.05)。

表3 饲粮能量水平对空怀期滩羊能量摄入量和平均日增重的影响

Table 3 Effects of dietary energy level on energy intake and average daily gain of Tan sheep during non-pregnancy period

组别 Groups	干物质采食量 DMI/(g/d)	能量摄入量Energy intake/(MJ/d)			初重 Initial weight/ kg	末重 Final weight/ kg	平均日增重 ADG/(g/d)
组别 Groups	干物质采食量 DMI/(g/d)	总能GE	消化能DE	代谢能ME	初重 Initial weight/ kg	末重 Final weight/ kg	平均日增重 ADG/(g/d)
Ⅰ	1 630.91±53.78^a	20.98±0.69^ab	11.00±0.36^Bb	9.05±0.30^Bc	34.00±1.58	36.48±1.70	82.67±8.34^Cc
Ⅱ	1 518.90±108.78^ab	19.84±1.42^b	11.15±0.80^Bb	9.42±0.68^Bbc	33.67±1.16	36.63±0.84	98.61±14.19^BCb
Ⅲ	1 483.37±87.29^b	20.29±1.19^b	11.91±0.70^ABb	10.13±0.60^Bb	33.94±2.03	37.35±2.15	113.64±8.13^Bb
Ⅳ	1 506.88±53.37^ab	22.05±0.78^a	13.20±0.47^Aa	11.33±0.40^Aa	33.54±0.84	37.83±0.98	142.95±7.44^Aa

	同列数据肩标不同大写字母表示差异极显著(P<0.01),不同小写字母表示差异显著(P<0.05),相同小写字母或无字母表示差异不显著(P>0.05)。
	In the same column, values with different capital letter superscripts mean extremely significant difference (P<0.01), and with different small letter superscripts mean significant difference (P<0.05), while with the same small letter or no letter superscripts mean no significant difference (P>0.05).

2.3 空怀期滩羊消化能和代谢能需要量回归分析

通过对表3相关数据进行回归分析,分别建立空怀期滩羊消化能和代谢能营养需要量与代谢体重(W^0.75)和平均日增重的回归方程如下:消化能需要量(MJ/d)=0.527 2W^0.75+0.040平均日增重(R²=0.897,P<0.01);代谢能需要量(MJ/d)=0.401 6W^0.75+0.040平均日增重(R²=0.942,P<0.01)。由此可知,空怀期滩羊代谢能维持需要量(MEm)为401.6 kJ/kg W^0.75,每100 g日增重需要代谢能400.0 kJ。

3 讨论

3.1 饲粮能量水平对空怀期滩羊能量消化代谢的影响

羊的能量消化代谢过程中,粪能、尿能和甲烷能是主要的损耗部分。其中,羊摄入的总能中粪能损失量为20%~50%^[13]。研究发现,饲粮能量水平提高,粪能损失量也随之提高^[14⇓-16],本试验中,Ⅳ组总能摄入量最高为22.31 MJ/d,Ⅰ组粪能损失量最高为9.80 MJ/d,与上述研究结果并不一致,可能是与饲粮组成中粗饲料的占比不同有关。研究发现,道寒杂交母羊妊娠前期和后期粪能损失量分别为46.64%~49.38%和33.15%~36.93%^[17],杜蒙杂交F1代绵羊妊娠期和空怀期粪能损失量为35%~43%^[18],本试验中滩羊空怀期粪能损失量为40.00%~47.66%,与上述结果基本一致。尿能损失量占总能摄入量的4%~5%,且受饲粮组成、蛋白质水平以及氨基酸平衡状态的影响,本试验中尿能损失量约为1.6%,低于此水平,接近于辽宁绒山羊空怀期^[19]和云南半细毛羊生长期^[20]的尿能损失量1.34%和1.07%,可能是因为本试验中饲粮粗蛋白质水平较接近或低于滩羊空怀期蛋白质需要量,导致尿能损失量低于一般水平。而甲烷能由消化能转化而来,占总能的5%~15%^[21],通过呼吸测热试验测得20~35 kg杜寒杂交公羔羊甲烷能占总能的7.45%~8.75%^[22]、德国美利奴杂交育肥羊甲烷能约占总能的9.4%^[23],通过Blaxter法测算陕北白绒山羊空怀期甲烷能约占总能的7.78%^[24]、滩羊育成期甲烷能约占总能的7.58%^[25]、云南半细毛羊生长期甲烷能约占总能的7.87%^[20]。本试验测算甲烷能约占总能的7.19%,接近滩羊育成期水平,低于其他品种,可能是由于在不同品种瘤胃内能量利用的过程中,因微生物的组成差异致使甲烷能并不一致。此外,本试验结果还显示甲烷能与饲粮能量水平呈正相关,这与李柏浩^[26]的研究结果一致。羊对饲粮中能量的利用效率影响有效能的摄入量^[25],且与品种、性别、生理阶段及环境等因素有关^[13]。研究发现,高山美利奴育成期母羊总能消化率和总能代谢率分别为60.64%~65.49%和58.84%~63.63%^[27],35~50 kg道寒杂交母羔总能消化率和总能代谢率分别为75.89%~79.42%和52.37%~60.78%^[28],杜寒杂交F1代绵羊空怀期总能消化率和总能代谢率分别为52%~56%和40.85%~46.69%^[29],滩羊妊娠前期和后期总能消化率、总能代谢率分别为54.90%~63.84%、46.03%~54.61%和55.07%~64.30%、46.24%~55.22%^[30],藏西北白绒山羊妊娠后期总能消化率和总能代谢率分别为61.62%和36.77%^[31],相较之下不同生理状态下能量利用效率呈现生长期>妊娠后期>妊娠前期>空怀期的规律。而在本研究中,滩羊空怀期总能消化率和总能代谢率分别为52.42%~59.85%和43.14%~51.36%,接近于杜寒杂交F1代绵羊空怀期和滩羊妊娠前期研究结果,但低于其他研究结果,这可能是由于品种、生理阶段及环境不同。这与此前所报道,在相同饲养条件下不同品种羔羊对饲料的利用率并不相同的结果^[32]相似。

3.2 滩羊空怀期能量需要量

空怀期是断奶后到再次配种之间的时期,是开展体况复壮、蓄积配种需要和胎儿早发育营养的重要时期^[33-34]。饲粮营养水平过高、过低以及不均衡都会造成能量供应的不平衡,引起母羊空怀期延长^[35]。在纯种绵羊的研究中,张崇玉等^[36]、杨在宾等^[37]和武渝瀚^[38]分别开展了大尾寒羊、小尾寒羊和云南半细毛能量需要量的研究,得出代谢能维持需要量分别为414.2、402.0和372.193 kJ/kg W^0.75;在杂交绵羊的研究中,楼灿等^[29]、崔璨^[18]和张少丰^[39]分别研究报道了杜泊×小尾寒羊、杜泊×蒙古羊和萨克福×阿勒泰羊代谢能维持需要量分别为372.37、200.17和292.72 kJ/kg W^0.75,均低于NRC(1981)^[40]绵羊代谢能维持需要量424.0 kJ/kg W^0.75。此前有研究报道,随着产业的发展,通过育种的选择,每千克代谢体重基础代谢增加,国外现行标准确需更新^[41]。在山羊的研究中,杨在宾等^[42]、李瑞丽等^[19]和王惠^[24]分别研究报道了青山羊、辽宁绒山羊和陕北绒山羊代谢能维持需要量分别为390.16、480和413 kJ/kg W^0.75。在滩羊的研究中,李志凤^[25]、杨凡提^[30]和孙涛^[16]分别报道了育成期、妊娠期、泌乳前期和泌乳后期代谢能维持需要量分别为423.0、392.2、761和685 kJ/kg W^0.75。以上试验结果发现,空怀期能量需要量与品种、饲养环境及生理阶段组成有关。本研究表明,滩羊空怀期代谢能维持需要量为401.6 kJ/kg W^0.75,接近云南半细毛羊、小尾寒羊、大尾寒羊空怀期和滩羊妊娠期代谢能维持需要量。有研究利用数学模型对多个研究结果分析发现,热带和温带地区绒毛用羊营养需求不同^[43],杂交和纯种羊能量需要量也存在差异^[10],因此国内外饲养标准并不能完全应用于各地方品种。而在集约化养殖模式2年3胎下的繁育体系中,空怀期营养需求是制约发挥基础母羊生产性能发挥的重要因素。综上所述,本试验中对滩羊空怀期能量需要量的研究结果可以为滩羊科学饲喂体系的建立、生产性能的发挥以及产业收入的提升提供重要参数。

4 结论

① 随着饲粮能量水平的提高,滩羊空怀期平均日增重逐渐提高,干物质采食量先降低后升高。

② 在本试验条件下,滩羊空怀期对4种能量水平饲粮的总能消化率和总能代谢率分别为52.42%~59.85%和43.14%~51.36%。

③ 在本试验条件下,建立滩羊空怀期消化能和代谢能需要量回归方程分别为:消化能需要量(MJ/d)=0.527 2W^0.75+0.040平均日增重(R²=0.897,P<0.01);代谢能需要量(MJ/d)=0.401 6W^0.75+0.040平均日增重(R²=0.942,P<0.01);其代谢能维持需要量为401.6 kJ/kg W^0.75,每100 g日增重需要代谢能400.0 kJ。

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