Evolution of Feeding Systems

Transcription

1 Evolution of Feeding Systems Nutrition 202 Advanced Nutritional Energetics R. D. Sainz Lecture 05 Feeding Systems Objectives: To predict the ability of different feeds to support given levels of animal production To formulate diets to meet animal requirements in the most cost-effective manner Needs: Accurate estimation of nutritive value of feeds Knowledge of energy requirements of animals of different classes for various productive functions Energy partition in steers IE E feces DE E urine E gases ME NEm NEg

2 Total energy content of feed is inadequate, because of multiple energy losses, such as: Fecal energy 15 50% Urinary energy 3 7 % Gaseous energy 5 10% (ruminants) Heat losses 15 45% Concentrate diet Forage diet Metabolizable energy Feces 41% 18% Metabolizable energy 67% Urine 3% Gas 6% Heat of fermentation 6% Feces 43% Heat of Gas fermentation 6% Urine 6% 4% Historical landmarks : Albert Thaer ( ) Henneberg & Stohmann (1864) Wolff (1864) Armsby (1880) Henry (1898) Atwater & Bryant (1900) Kellner (1905) Also: Scandinavian fodder unit Blaxter (1962) Current Hay equivalents Weende analysis: crude fiber, crude protein, nitrogen-free extract, ether extract Digestible nutrients Manual of Cattle Feeding ; incl. TDN Feeds and Feeding ; TDN Physiological Fuel Values Starch equivalents (net energy for fattening) Factorial approach: split total energy requirements into various parts (maintenance, physical activity, milk production, body gain, etc.) Systems based upon TDN, DE, ME, NE Digestible energy DE = IE FE Accounts for the major energy loss from feed; other large losses unaccounted for.

3 Total Digestible Nutrients (TDN) TDN (%) = % digestible crude protein + % digestible fiber + % digestible nitrogen-free extract + % digestible ether extract x 2.25 Requirements: calculated by summing TDN requirements for maintenance and production TDN - problems Different energy values for TDN from forages and concentrates 1 kg forage TDN = 4.0 Mcal DE 1 kg concentrate TDN = 4.4 Mcal DE TDN requirements for different functions are not additive Metabolizable energy ME = IE FE UE GE Accounts for most feed-related losses Does not account for animal-related energy losses Prediction of performance depends upon application of efficiency factors for each function (k m, k g, k l ), which also vary according to diet quality.

4 USDA (humans) Equations adopted from WHO (1985) Energy allowances expressed as kcal per day of physiologically available energy (i.e. the amount of potential food energy that can be absorbed and utilized). Food tables list available energy values based on the Atwater system (PFV; 4, 4, 9); not used for fibrous plant foods, or ethanol (5.7 kcal/ml). Requirements estimated by summing energy expenditures at rest, in physical activity, and for thermogenesis (plus growth, pregnancy, lactation). Physiological Fuel Values (PFV) Heat of combustion (kj/g) Assumed digestion coefficient Digestible energy (kj/g) Assumed loss in urine (kj/g) PFV (kj/g) CH 2 O None Protein Fat None Note that / = 4 and 37.65/4.184 = 9; therefore CH 2 O, protein and fat have PFVs of 4, 4, and 9 kcal/g. Net energy NE = RE = IE FE UE GE HE Feed energy expressed in units directly equivalent to the animals requirements for maintenance and production.

5 E.g., NRC (1996); beef cattle 1. Feed Estimate TDN DE = TDN (kg) x 4.4 Mcal/kg ME = 0.82 DE NE m = 1.37 ME ME ME NEg = 1.42 ME ME ME Animal NE m (Mcal/day) = W 0.75 with adjustments for breed, sex, age, temperature (current and previous), external insulation, activity, physiological state and previous nutrition. RE = EQEBW 0.75 EBG where EQEBW is equivalent empty body wt (adjusted for frame size); in typical feedlot situations, the NRC (1996) has prediction errors below 2 3%. Starch equivalents SE feed values expressed as amount of energy stored as fat per kg of feed provided above maintenance, compared to energy retained per kg starch provided above maintenance Requirements estimated as the sum of requirements for maintenance and production

6 Forage units Similar system to SE (used in France). AFRC, 1993 Agricultural and Food Research Council Energy and Protein Requirements of Animals. CAB International, Wallingford, UK. AFRC, 1993 ME = GE FE UE M E M E is methane NE = ME x k k is the efficiency of utilization of ME for the relevant function ME is determined at maintenance feeding level q m = [ME] / [GE] (metabolizability)

7 AFRC, 1993 Fermentable metabolizable energy (FME): FME (MJ/kg DM) = [ME] [ME fat ] [ME ferm ] Used to calculate the metabolizable protein (i.e., rumen microbial growth) AFRC, 1993 Efficiencies of ME utilization Maintenance k m = 0.35 q m Lactation k l = 0.35 q m kt = 0.84 Growth k f = 0.78 q m k g = 0.95 k l (diet energy) (body tissue) (growing ruminants) (lactating ruminants) Gestation k c = AFRC, 1993 Corrections for feeding level Lactating ruminants C L = (L-1) L is multiples of maintenance ME intake Growing and fattening animals R = B (1-e -ki ) 1 R is energy retention, I is ME intake; both are scaled by FHP And: B = k m / (k m k f ) k = k m ln(k m /k f )

8 AFRC, 1993 Maintenance requirements M m (MJ/d) = (F + A)/k m F is fasting metabolism and A is activity allowance F (MJ/d) = C1 (0.53 (W/1.08) 0.67 ) C1 = 1.15 for bulls, 1.0 for other cattle A (MJ/d) = W + Different equations for other ruminant classes AFRC, 1993 Intellectually sound RE tends to be over-estimated by 10-20% AFRC recommends adding a 15% safety margin SCA, 1990 Standing Committee on Agriculture Feeding Standards for Australian Livestock. CSIRO Publications, East Melbourne, Australia.

9 SCA, 1990 Similar calculations of q m, k m, k g, k l, k c Also: M / D: M / D = 0.18 DOMD% M /D = 0.16 OMD% M / D = 0.17 DMD% M / D = MADF (temperate forages) M / D = MADF (tropical forages) etc. SCA, 1990 Maintenance energy requirements K S M 028. W e MEm ( MJ / d) = k m A EGRAZE ME p + + ECOLD k m K = 1.0 for sheep and goats, 1.2 for B. indicus, 1.4 for B. taurus S = 1.0 for females and castrates, 1.15 for intact males M = x % milk in diet DE W = live weight (kg) A = age in years; maximum value = 6 MEp = proportion of ME used for production EGRAZE = additional energy of grazing ECOLD = additional energy needed below lower critical temperature SCA, 1990 Additional properties Effects of heat and cold Effects of wind Acclimatization Requirements for drought feeding Wool growth Etc.

10 INRA Jarrige, R (ed.) Ruminant Nutrition. Recommended Allowances and Feed Tables. INRA, Paris. INRA NE = ME H d E Each feed has two NE values: UFL = unité fouraggère lait UFV = unité fouraggère viande One UFL (or UFV) is the NE content of 1 kg standard barley for milk (or meat) production Barley: 1700 kcal NE l /kg, 1820 kcal NE mg /kg k m = q k f = 0.78 q INRA Net energy system Estimates mean efficiency for maintenance and gain Units barley (?) Includes estimates of feed intake capacity and fill value of feeds

11 NRC 1996/2000 National Research Council Nutrient Requirements of Beef Cattle, 7th Revised Edition. Update National Academy of Sciences, Washington, DC. Published and revised 7 times since World War II, to facilitate increased production and efficiency. Committee members are scientists who contribute to each revision. NRC 1996/ kg TDN = 4.4 Mcal DE ME = IE FE UE GE, or ME = DE (UE + GE) ME = HE + RE Feed NE = RE / IE (linear) Non linearity approximated by two straight lines, above and below RE = 0, respectively (i.e., maintenance) NE m = H e E/ I m NE g = RE / (I I m ) ME = RE + H e E+ H j E+ H i E (HiE = heat increment of IE) NRC 1996/2000 RE = LE + TE + YE, or NE g = NE l + NE g + NE y ME = NE l + NE g + NE y + NE m + H i E Advantage: animal requirements are independent of diet quality and feed values are stated in the same units! NE m = 1.37 ME ME ME NE g = 1.42 ME ME ME Garrett (1980): 2766 animals fed mixed diets for d Digestion trials at 1.1 maintenance ME = 0.82 DE Zinn: NE g = NE m 0.41

12 NRC, 2000 NE m = a W 0.75 a 1 = Adjustment for previous temperature: a 2 = (20-T p ) Adjustment for breed, lactation, previous plane of nutrition: NE m = SBW 0.75 ((a 1 BE L COMP) + a 2 ) COMP = ((CS - 1) 0.05 BE is breed effect, L is lactation effect (1 if dry, 1.2 if lactating), CS is condition score (1-9) NRC, 2000 Adjustment for activity (on pasture): NE mact = ((0.06 pi (0.9 TDNp/100)))+(0.05 TERRAIN/(( pavail)+3))) BW/4.184 pi is pasture DM intake, kg/d TDNp is pasture TDN, % TERRAIN is 1 (level) to 2(hilly) pavail is available pasture mass, T/ha Adjustment for activity (fed cattle): NE mact = 0 Adjustment for cold stress: SA = 0.09 BW 0.67 HE = (MEI (RE + LE + YE))/SA EI = ( WIND HAIR) MUD2 HIDE SA is surface area, m 2 EI is external insulation value, ºC Mcal-1 m2 d WIND is wind speed, km/h HAIR is effective hair depth, cm MUD2 is 1 (dry and clean) to 0.2 (wet snow or mud) HIDE is 0.8 (thin) to 1.2 (thick) NRC, 2000 Adjustment for cold stress: SA = 0.09 BW 0.67 HE = (MEI (RE + LE + YE))/SA EI = ( WIND HAIR) MUD2 HIDE SA is surface area, m 2 EI is external insulation value, ºC Mcal-1 m2 d WIND is wind speed, km/h HAIR is effective hair depth, cm MUD2 is 1 (dry and clean) to 0.2 (wet snow or mud) HIDE is 0.8 (thin) to 1.2 (thick) LCT = 39 (IN HE 0.85) IN = TI + EI TI is internal insulation value, ºC Mcal-1 m2 d If LCT > T c, then ME cs = SA (LCT T c )/IN; otherwise, ME cs = 0 NE mcs = k m ME cs NE m total = NE m + NE mact + NE mcs

13 Limitations of the NRC system Maintenance requirements are not constant Cannot be used beyond original conditions Need new adjustment factors for each new situation Adjustment factors are not additive Feeding systems INRA, 1989 NE system Barley-based feed units Similar to Scandinavian, German starch equivalent system SCA, 1990 ME system Developed mainly for sheep and cattle grazing temperate pastures AFRC, 1993 ME system Mainly based on calorimetry data Heavy emphasis on silage feeding NRC, 2000 NE system Based on comparative slaughter data Most recent version includes adjustment factors for breed, environment, activity Level 2 includes CNCPS Dietary Reference Intakes

14 RDA = EAR + 2 x SD requirement For energy, there is no RDA or UL; intakes above the EER will result in weight gain

15 BMR (= BEE) Rate of energy expenditure in the post-absorptive state, after an overnight fast (no food for 12 to 14 hours Resting, comfortable, supine, awake, motionless, thermoneutral Predicted from age, gender, and body size Mainly (70-80%) of variance accounted for by fat-free mass RMR Energy expenditure under resting conditions 10-20% higher than BEE

16 Thermic effect of food AKA Specific Dynamic Action 5-10% for carbohydrate 0-5% for fat 20-30% for protein ~10% for usual mixed diets Physical activity +50% above BEE in sedentary individuals +200% in active individuals PAL = TEE / BEE TEE: measured with doubly-labeled water method Equal to the sum of BEE TEF physical activity Thermoregulation Energy deposited in new tissues or milk TEE = A + B x Age + PA x (D x weight + E x height) Equations specific for gender, age, physiological state