Calculation method for net protein requirement amount for maintenance and growth of yak

Abstract

The invention discloses a yak maintenance and growth net protein demand amount calculation method, and relates to the technical field of livestock breeding, and the method comprises the following steps: obtaining basic data of adult yaks through experiments, calculating the maintenance net protein demand amount, and building a growth net protein demand amount model; according to the method, the gradient feeding test, the nitrogen metabolism test and the comparative slaughtering test are integrated, protein metabolism and body composition first-hand data of the plateau adult yaks are directly obtained, an accurate mathematical model is established according to the data, the calculation result directly reflects the real physiological needs of the yaks, scientificity is remarkably enhanced, and based on the model, the real physiological needs of the yaks are directly reflected. By means of the method, the net protein requirement amount for maintaining the net protein and the net protein requirement amount for growth required by target weight gain of the yaks of any weight can be accurately calculated, the feed utilization efficiency can be greatly improved, the feeding cost can be reduced, nutrient emission can be reduced, and the growth performance of the yaks can be optimized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of livestock breeding, and in particular to a method for calculating the maintenance and growth net protein requirement of a yak. BACKGROUND

[0002] Yak is a representative livestock resource in the Qinghai-Tibet Plateau, and its multiple products such as wool, milk and meat, and draft play a core role in the economic structure of the alpine pastoral area. For a long time, yak production has been highly dependent on natural grassland supply, and the extensive grazing mode has made the protein nutrition level of yak significantly affected by season and ecological conditions. Especially in the winter and spring when the quality of grassland decreases and edible forage is scarce, yaks are often in a state of obvious protein deficiency, which is difficult to meet the basic physiological needs of body tissue renewal, wool growth and immune function maintenance. Protein is a key nutrient for yaks to adapt to low temperature environment, maintain normal metabolism and resist external stress, and long-term deficiency will cause tissue decomposition, growth and development inhibition, wool quality decline, reproduction performance impairment and weakened disease resistance, which seriously limits the industry benefit and population health.

[0003] The current feeding standard mainly depends on the nutrition model of low-altitude beef cattle, and the net protein requirement parameters lack systematic consideration of the special physiological and metabolic characteristics of yaks. Yaks have formed a unique rumen microbial protein synthesis mode, nitrogen recycling mechanism and amino acid metabolism regulation strategy to adapt to the high-cold and low-oxygen environment in long-term evolution, which determines the protein requirement of yaks with obvious species specificity. The general model cannot accurately reflect the real net protein requirement of yaks under environmental stress, resulting in problems such as insufficient supply or low utilization rate in feeding management, which affects the implementation of precise nutrition strategy.

[0004] Under the dual drive of grassland ecological protection on the plateau and yak industry transformation and upgrading, it is urgent to establish a parameter system of maintenance and growth net protein requirement that meets the physiological characteristics of yaks and is based on their own metabolic rules. This system is not only the key basis for developing yak-specific protein supplements and improving the amino acid balance of the diet, but also an important scientific basis for achieving precise supplemental feeding in the cold season, improving wool and meat quality, and enhancing population health and production efficiency. Its construction will provide solid technical support for the optimization of industrial structure, income growth of herdsmen and ecological security maintenance in the alpine pastoral area, and has significant practical value and strategic significance.

[0005] Therefore, the present application provides a method for calculating the maintenance and growth net protein requirement of a yak to solve the problems in the prior art. SUMMARY

[0006] In view of the above problems, the purpose of the present application is to provide a calculation method of net protein requirement of yak maintenance and growth, so as to systematically determine the protein requirement parameters of adult fattening yak, provide a basis for precise feeding strategy in plateau areas, improve production efficiency and resource utilization rate, and promote the sustainable development of yak breeding industry.

[0007] In order to achieve the purpose of the present application, the present application realizes the following technical scheme: a calculation method of net protein requirement of yak maintenance and growth, comprising the following steps:

[0008] Step one: based on the gradient feeding test, nitrogen metabolism test and comparative slaughter test of yak, the basic metabolism data and tissue composition data of adult yak are obtained;

[0009] Step two: according to the basic metabolism data and tissue composition data obtained in step one, the maintenance net protein requirement NPm of adult yak is calculated by establishing the regression relationship between nitrogen intake and nitrogen deposition;

[0010] Step three: according to the tissue composition data obtained in step one, the growth net protein requirement NPg calculation model of adult yak is constructed by establishing the regression relationship between fasting body weight and body protein content of yak.

[0011] Further improvement lies in that in step one, the specific steps of the gradient feeding test are:

[0012] Healthy adult male yaks with a body weight of 230-320 kg are randomly divided into a high feeding amount group, a medium feeding amount group and a low feeding amount group, and are respectively fed with daily rations of free feeding amount, 70% of free feeding amount and 40% of free feeding amount, the test period includes a 15-day pre-feeding period and a 90-day normal test period, and the concentrate-roughage ratio of the daily ration is 65:35.

[0013] Further improvement lies in that in step one, the specific steps of the nitrogen metabolism test are:

[0014] Before the end of the normal test period of the gradient feeding test, the feces and urine of the yak are continuously collected by using the whole collection of feces and urine method, the ingested nitrogen, fecal nitrogen and urinary nitrogen are measured, and the nitrogen digestibility, nitrogen digestion amount and nitrogen deposition amount are calculated.

[0015] Further improvement lies in that in step one, the specific steps of the comparative slaughter test are:

[0016] After the start of the gradient feeding test, when the body weight of the yak reaches 242.20 kg, 264.80 kg and 320.20 kg, a predetermined number of yaks are slaughtered as the initial slaughter group, the middle slaughter group and the final slaughter group, after slaughter, the skeleton, muscle, fat, blood-containing internal organs, skin and hair tissue are completely separated and weighed, the dry matter content and protein content of each tissue are measured, and the total body protein is calculated.

[0017] Further improvement lies in that: in step two, the maintenance net protein requirement NPm is determined by the following way:

[0018] The regression equation between the nitrogen deposition amount RN and the nitrogen intake amount NI is established:

[0019] RN = e x NI + f

[0020] Wherein, e and f are constants obtained by fitting the test data;

[0021] The maintenance net protein requirement NPm is equal to the absolute value of the intercept f in the regression equation multiplied by 6.25, that is, NPm = |f| x 6.25.

[0022] Further improvement lies in that: in step three, the growth net protein requirement NPg calculation model is:

[0023] NPg = g x EBW h x EBG

[0024] Wherein, EBW is the empty body weight, EBG is the empty body weight gain, and g and h are constants derived from the regression relationship between body protein and empty body weight established by comparing the slaughter test data.

[0025] The beneficial effects of the present application are: the present application directly obtains the protein metabolism and body composition of adult yaks on the plateau by systematically integrating gradient feeding, nitrogen metabolism test and comparative slaughter test, and establishes a precise mathematical model accordingly, and the calculation results directly reflect the real physiological needs of yaks, and the scientificity is significantly enhanced, based on the model, the maintenance net protein requirement of any weight yak and the growth net protein requirement required for target weight gain can be accurately calculated, which provides a core technical basis for realizing the precise ration preparation of individual or group yaks, not only can greatly improve the feed utilization efficiency, reduce the feeding cost, reduce the nutrient discharge, but also can optimize the growth performance of yaks, lay a solid foundation for establishing a special yak feeding standard system, and the social and economic benefits are remarkable. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 It is the flowchart of the calculation method of the maintenance and growth net protein requirement of yaks of the present application. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present application will be clearly and completely described with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort belong to the scope of the present application.

[0028] It should be noted that the technical means not described in detail in the following embodiments all adopt conventional means in the art, which are not the key points of the present application, and will not be described here.

[0029] Embodiment 1

[0030] Referring to Figure 1 The present embodiment provides a calculation method of yak maintenance and growth net protein requirement, comprising the following steps:

[0031] Step one, obtaining adult yak basic data through experiments

[0032] Gradient feeding test, nitrogen metabolism test and comparative slaughter test are performed on the yak, and based on the gradient feeding test, nitrogen metabolism test and comparative slaughter test, the basic metabolic data and tissue composition data of the adult yak are obtained, specifically:

[0033] 1. Gradient feeding test:

[0034] Test animals and grouping: 24 healthy 4-year-old male yaks with similar body weight (235.96±12.46 kg) are selected, and a randomized block design is adopted, and the yaks are divided into 3 groups, 8 yaks in each group, including:

[0035] High feeding amount group (AL group): free feeding;

[0036] Medium feeding amount group (IR70 group): the feeding amount is 70% of the average feeding amount of the day before the high feeding amount group;

[0037] Low feeding amount group (IR40 group): the feeding amount is 40% of the average feeding amount of the day before the high feeding amount group;

[0038] Test feed and management: the total mixed ration (TMR) is designed according to the "Beef Cattle Feeding Standard" (NY / T 815-2004), and the concentrate-conifer ratio can be 65:35 (in this embodiment, 65:35 is taken as an example, and the composition and nutritional level are shown in Table 1). The test lasts for 105 days, including a 15-day pre-feeding period and a 90-day test period. The yaks are fed twice a day at 8:00 and 17:00, free water is provided, and the yaks are single-pen fed in consistent environmental conditions.

[0039] 2. Nitrogen metabolism test:

[0040] The "total feces and urine collection method" was used for 5 consecutive days before the end of the test period, specifically:

[0041] Sample collection: feces were collected every 2 hours, mixed uniformly, and 10% of the total fecal output was taken for nitrogen fixation with 10% concentrated sulfuric acid. Urine was collected every 2 hours by a special urine bag, and 5% of the total urine was stored at -20°C;

[0042] Index determination: dry matter and nitrogen content in feed, feces, and urine were determined (using the Kjeldahl nitrogen determination instrument);

[0043] Data calculation: calculate the nitrogen intake (NI), fecal nitrogen, and urinary nitrogen, and then obtain key metabolic parameters such as nitrogen digestibility and nitrogen deposition (RN). Typical data results are shown in Table 4.

[0044] 3. Comparison of slaughter test:

[0045] This test aims to determine the protein content and its distribution in the body of yaks, specifically:

[0046] Test design and grouping: an additional 40 similar yaks were selected and divided into:

[0047] Initial slaughter group: 5 yaks were slaughtered when their body weight reached 242.20 kg;

[0048] Mid-term slaughter group: 5 yaks were slaughtered when their body weight reached 264.80 kg;

[0049] Final slaughter group: the remaining 30 yaks were slaughtered in groups of 5 when their body weight reached 320.20 kg (divided into AL, IR70, and IR40 feeding level groups), for a total of 15 yaks;

[0050] Slaughter and sample processing: yaks were slaughtered after 16 hours of fasting. Six major tissues, including bone, muscle, fat, internal organs (including blood), skin, and hair, were separated and weighed. The tissue samples were freeze-dried, pulverized, and homogenized for use;

[0051] Index determination: dry matter content and crude protein content of each tissue were determined (Kjeldahl nitrogen determination instrument). Tissue growth data and protein content distribution data are shown in Tables 2 and 3, respectively.

[0052] Step two, calculation of maintenance net protein requirement

[0053] Based on the basal metabolic data and tissue composition data obtained in Step One, the regression relationship between nitrogen intake and nitrogen deposition was established to calculate the maintenance net protein requirement NPm of adult yaks. The specific steps are as follows:

[0054] Data basis: Nitrogen intake (NI, g / kg SBW) of yaks in the AL, IR70, and IR40 groups was summarized in the final slaughter group and nitrogen metabolism trial. 0.75 ·d -1 ) and nitrogen deposition (RN, g / kg SBW) 0.75 ·d -1 );

[0055] Model establishment and parameter acquisition: Linear regression was performed with NI as the independent variable and RN as the dependent variable. The regression equation obtained was: RN = 0.5033 × NI - 0.4409, R² 2 =0.9583;

[0056] Calculate NPm: the mass of protein converted from nitrogen deposition (i.e., loss) when maintaining net protein intake (NPm) at zero nitrogen intake. Setting NI=0, we get RN=0.4409 g / kg SBW. 0.75 ·d -1 Multiplying the nitrogen value by a constant of 6.25 to convert it to protein yields: NPm = 0.4409 × 6.25 ≈ 2.76 g / kg SBW 0.75 ·d -1 Based on a more precise intercept calculation, NPm = 2.76 g / kg SBW 0.75 ·d -1 .

[0057] Step 3: Establishing a net protein requirement model for growth

[0058] Based on the tissue composition data obtained in step one, a model for calculating the net growth protein requirement (NPg) of adult yaks is constructed by establishing a regression relationship between fasting body weight and body protein content. The specific steps are as follows:

[0059] Data basis: Based on data from 15 yaks in three groups (BL, M, AL) in a comparative slaughter trial, the fasting body weight (EBW, kg) and total body protein (CP, g) of each yak were obtained.

[0060] Model building and parameter acquisition: After logarithmic transformation of EBW and CP, regression was performed to obtain the relationship: Log 10 (CP) = 1.2488 × Log 10 (EBW)+1.7723, R 2 =0.8850;

[0061] Derivation of the NPg model: Differentiating the allometric growth equation yields the net protein requirement (NPg) model for growth: NPg = 73.9253 × EBW 0.2488 ×EBG, where NPg is in g / d.

[0062] Table 1. Nutritional composition and nutrient levels of the experimental diets (dry matter basis)

[0063]

[0064] In Table 1 above, the premix provides 4000 IU of VA, 500 IU of VD, 40 IU of VE, 30 mg of Mn, 65 mg of Fe, 0.1 mg of Co, 10 mg of Cu, 25 mg of Zn, 0.1 mg of Se, and 0.5 mg of I per kilogram of feed. The metabolizable energy is a calculated value, and the rest are measured values.

[0065] Table 2. Growth performance and tissue growth of adult yaks at different slaughter stages and feeding levels.

[0066]

[0067] Example 2

[0068] This example calculates the maintenance requirements of an adult male yak weighing 280kg, as follows:

[0069] Given: Pre-slaughter live weight SBW = 280 kg;

[0070] Calculate metabolic weight: SBW 0.75 =280 0.75 ≈68.45kg 0.75 ;

[0071] Calculate the maintenance net protein requirement (NPm): Based on the parameters determined according to this invention, NPm = 2.76 g / kg SBW 0.75 ·d -1 Therefore, the total net protein requirement for this cow is approximately 2.76 × 68.45 g / d.

[0072] Results: The daily maintenance net protein requirement for this adult male yak, weighing 280 kg, is approximately 188.92 g. This data forms the basis for accurately formulating its maintenance diet.

[0073] Example 3

[0074] This example describes the formulation of a growth diet for the yaks in Example 2, aiming for a daily weight gain of 0.5 kg. Specifically:

[0075] Given conditions: live weight BW = 280 kg, target daily weight gain 0.5 kg / d;

[0076] Estimating fasting body weight and fasting weight gain: Using the regression equation established through comparative slaughter trials in this invention: EBW = 0.9384 × BW - 27.831. The calculated EBW ≈ 0.9384 × 280 - 27.831 ≈ 235 kg. Assuming that fasting weight gain (EBG) is similar to live weight gain, we take EBG = 0.5 kg / day;

[0077] Calculate the net protein requirement for growth (NPg): Substitute EBW = 235 kg and EBG = 0.5 kg / d into the net protein requirement model established in this invention: NPg = 73.9253 × EBW 0.2488 ×EBG. Calculation yields: NPg≈73.9253×(235) 0.2488 ×0.5≈73.9253×3.89×0.5≈143.78g / d;

[0078] Calculate the total requirement and apply it:

[0079] Total net protein requirement = NPm + NPg = 188.92 + 143.78 = 332.72 g / d;

[0080] Based on the above net protein requirement and the digestible crude protein content of the selected feed ingredients, the daily intake of concentrate and roughage required for the yak to achieve a daily weight gain of 0.5 kg can be accurately calculated using existing ration formulation software, thus achieving precise feeding.

[0081] Example 4

[0082] This embodiment evaluates the effects of different feeding levels on nitrogen metabolism, as detailed below:

[0083] Data source: Directly cited results from the experiment in Example 1 (Table 4);

[0084] Comparative analysis:

[0085] Digestive and metabolic efficiency: From the AL group to the IR40 group, nitrogen digestibility (NAD) increased significantly from 65.97% to 68.16% as the feeding level decreased. This indicates that yaks have higher efficiency in digesting and metabolizing feed nitrogen under restricted feeding conditions.

[0086] According to the above embodiments, the implementation process and the resulting data clearly demonstrate that, under moderately restricted feeding conditions, adult yaks achieve higher nitrogen utilization efficiency by improving the digestibility and metabolic rate of feed nutrients. This provides a direct scientific basis for formulating differentiated feeding strategies for yaks (such as full feeding during the fattening period to pursue growth rate, and moderately restricted feeding during the maintenance period or winter dry season to ensure health and save feed).

[0087] Table 4. Effects of different feeding levels on nitrogen metabolism in adult yaks

[0088]

[0089] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for calculating the net protein requirement for maintenance and growth in yaks, characterized in that, Includes the following steps: Step 1: Based on gradient feeding trials, nitrogen metabolism trials, and comparative slaughter trials of yaks, obtain basal metabolic data and tissue composition data of adult yaks; Step 2: Based on the basal metabolic data and tissue composition data obtained in Step 1, the maintenance net protein requirement (NPm) of adult yaks is calculated by establishing a regression relationship between nitrogen intake and nitrogen deposition. Step 3: Based on the tissue composition data obtained in Step 1, a model for calculating the net protein requirement (NPg) for growth in adult yaks is constructed by establishing a regression relationship between the fasting body weight and the body protein content.

2. The method for calculating the net protein requirement for maintenance and growth in yaks according to claim 1, characterized in that: In step one, the specific steps of the gradient feeding experiment are as follows: Healthy adult male yaks weighing 230–320 kg were selected and randomly divided into high-feeding-amount, medium-feeding-amount, and low-feeding-amount groups. They were fed diets with free-feeding, 70% of free-feeding, and 40% of free-feeding, respectively. The experimental period included a 15-day pre-feeding period and a 90-day trial period. The concentrate-to-roughage ratio of the diets was 65:

35.

3. The method for calculating the net protein requirement for maintenance and growth in yaks according to claim 2, characterized in that: In step one, the specific steps of the nitrogen metabolism test are as follows: Before the end of the formal trial period of the gradient feeding experiment, yak feces and urine were continuously collected using the total feces and urine collection method. Ingested nitrogen, fecal nitrogen and urinary nitrogen were measured, and nitrogen digestibility, nitrogen digestion amount and nitrogen deposition amount were calculated.

4. The method for calculating the net protein requirement for maintenance and growth of yaks according to claim 2, characterized in that: In step one, the specific steps of the comparative slaughter test are as follows: After the gradient feeding experiment began, once the yaks reached a weight of 242.20 kg, 264.80 kg, and 320.20 kg, a predetermined number of yaks were slaughtered as the initial slaughter group, the intermediate slaughter group, and the final slaughter group, respectively. After slaughter, the bones, muscles, fat, blood-containing internal organs, skin, and hair tissues were completely separated and weighed separately. The dry matter content and protein content of each tissue were measured, and the total protein content of the body was calculated.

5. The method for calculating the net protein requirement for maintenance and growth in yaks according to claim 1, characterized in that: In step two, the maintenance net protein requirement (NPm) is determined in the following way: Establish a regression equation between nitrogen deposition (RN) and nitrogen intake (NI): RN = e × NI + f Where e and f are constants obtained by fitting experimental data; The required net protein (NPm) is equal to the absolute value of the intercept f in the regression equation multiplied by 6.25, i.e., NPm = |f| × 6.

25.

6. The method for calculating the net protein requirement for maintenance and growth in yaks according to claim 1, characterized in that: In step three, the calculation model for net protein requirement (NPg) for growth is as follows: NPg=g×EBW h ×EBG Wherein, EBW is fasting body weight, EBG is fasting weight gain, and g and h are constants derived from the regression relationship between body protein and fasting body weight established by comparing slaughter test data.

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