scholarly journals The nitrogen and energy metabolism of lactating cows given abomasal infusions of casein

1986 ◽  
Vol 55 (3) ◽  
pp. 537-556 ◽  
Author(s):  
F. G. Whitelaw ◽  
J. S. Milne ◽  
E. R. Ørskov ◽  
J. S. Smith
Keyword(s):  
Milk Yield ◽  
Body Fat ◽  
Latin Square ◽  
Basal Diet ◽  
Progressive Increase ◽  
High Ratio ◽  
Primary Response ◽  
Metabolizable Energy ◽  
Energy Yield ◽  
Fat Mobilization

1. Four cows in early lactation were given continuous infusion into the abomasum of 0, 200, 400 or 600 g lactic casein/d according to a Latin-square design. Each period was of 14 d and the Latin square was followed by 7 d in which an infusion of 800 g glucose/d was given. The basal diet was given at a level which provided sufficient nitrogen and energy for 10 kg milk yield/d.2. Infusion of casein resulted in significant increases in milk yield, milk N yield and milk energy yield; milk N increased progressively but milk energy reached a maximum at 400 g casein/d. Milk yields and composition when glucose was infused resembled those seen on the zero casein treatment.3. N-balance measurements indicated a severe deficit (–20 g/d) on the zero casein treatment and a progressive increase to +7 g/d as casein increased; N equilibrium was achieved at about 400 g casein/d. The regression of net productive N on N intake (P< 0.001) indicated that the efficiency of utilization of dietary N did not differ between treatments.4. Heat production increased with increase in casein infused (P< 0.05) but remained a constant proportion of the metabolizable energy (ME) intake. Energy balances were negative and did not differ significantly between treatments but calculation of the protein and fat components indicated a threefold increase in body fat mobilization in response to the first increment of casein. Milk yield adjusted to zero energy balance was significantly related to ME intake (P< 0.001) but the efficiency of encrgy utilization was not affected by the level of casein infusion.5. The concentrations of glucose, β-hydroxybutyrate and non-esterified fatty acids in plasma did not differ between treatments but the concentration of urea in plasma increased markedly (P< 0.05) at the highest level of casein addition. Insulin concentrations increased and growth hormone decreased (bothP< 0.05) with increase in casein infusion.6. The concentration of total amino acids (AA) in plasma increased up to 400 g casein/d and then declined. Changes in concentration and in the ratio of essential: total AA indicated a very high extraction rate of essential AA at the lower levels of casein infusion.7. The observed lactational responses are discussed in relation to the ratio of protein:energy in the absorbed nutrients. It is concluded that the primary response to casein was the correction of an AA deficit and that body fat mobilization was secondary and occurred in response to the high ratio of AA-N:energy in the infused casein.

The effect of different proportions of hay and fortified rolled barley in the diet on digestible-energy value and urinary-energy excretion by cattle

1972 ◽  
Vol 79 (1) ◽  
pp. 99-103 ◽  
Author(s):  
A. M. Raven
Keyword(s):  
Organic Matter ◽  
Dry Matter ◽  
Rumen Fluid ◽  
Latin Square ◽  
Progressive Increase ◽  
Linear Increase ◽  
Metabolizable Energy ◽  
Digestible Energy ◽  
Gross Energy ◽  
Concentrate Treatment

SUMMARYA 6 x 6 Latin Square balance experiment was carried out using six Friesian steers, each of which initially weighed about 304 kg. The six treatments studied were an all-hay diet and five other diets containing 20,40,60,80 and 100 % of rolled barley fortified with mineral and vitamin supplements, accompanied by correspondingly reduced proportions of hay. Each diet was fed at an estimated maintenance level of feeding.The progressive increase in the proportion of concentrate gave a significantly linear increase (P < 0·001) in both digestible and calculated metabolizable energy. The actual increase in digestible energy was from 2·62Mcal/kg dry matter (59·3% of the gross energy) on the all-hay treatment to 3·42 Mcal/kg dry matter (79·5% of the gross energy) on the all-concentrate treatment. Use of the determined digestible energy values for the all-hay and fortified barley diets to calculate the digestible energy of the four mixed diets gave results in reasonably good agreement with the determined values, the maximum difference being 0·12 Mcal/kg dry matter, which represented 3·83 % of the determined value. The losses of energy in the urine expressed as percentages of the gross energy of the diets showed a small but significantly linear decrease (P < 0·01) with increase in proportion of barley in the diet. The molar proportions of steamvolatile acids in samples of rumen fluid taken from two animals on each treatment indicated that increase in the proportion of concentrate was associated with tendencies for increase in acetic acid, decrease in propionic acid and little change in butyric acid. The mean digestibility of the organic matter was 62·6 % on the all-hay treatment and 81·8 % on the all concentrate treatment. The progressive increase in the proportion of concentrate gave a significantly linear increase (P < 0·001) in digestibility of the organic matter. Although intakes of nitrogen decreased with increase in the proportion of concentrate due to a decrease in the amount of dry matter fed, the weights of nitrogen retained were well maintained and when expressed as percentages of intake showed a significantly linear increase (P < 0·01).

A comparison of starchy and fibrous concentrates for milk production, energy utilization and hay intake by Friesian cows

1987 ◽  
Vol 109 (2) ◽  
pp. 375-386 ◽  
Author(s):  
J. D. Sutton ◽  
J. A. Bines ◽  
S. V. Morant ◽  
D. J. Napper ◽  
D. J. Givens
Keyword(s):  
Milk Production ◽  
Milk Yield ◽  
Live Weight ◽  
Metabolizable Energy ◽  
Energy Utilization ◽  
Energy Yield ◽  
Carbohydrate Source ◽  
Lactating Cows ◽  
Concentrate Inclusion ◽  
Friesian Cows

SummaryTwenty-four Friesian cows were allocated to one of four diets for weeks 3–14 of lactation following 2 weeks on a common diet. The diets (kg air-dry feed/day) were 7–2 kg hay and 10·8 kg either starchy or fibrous concentrates (60S and 60F) or 3·5 kg hay and 14·0 kg either starchy or fibrous concentrates (80S and 80F). Rumen samples were taken by stomach tube in weeks 10 and 12 of lactation and the digestibility of the diets was measured with four cows per treatment during weeks 13 and 14. The digestibility of the same feeds was also measured in sheep at maintenance.The principal carbohydrate constituents of the concentrates were barley, wheat and cassava in the starchy concentrates and citrus pulp, sugar-beet pulp and wheat feed in the fibrous concentrates. The concentrates were designed to have similar concentrations of metabolizable energy (ME) and the diets were planned to provide similar intakes of digestible energy and crude protein.Milk yield and composition were very similar for treatments 60S and 60F. With the higher proportion of starchy concentrates (80S), milk yield was about 20% greater than on 60S, fat concentration fell severely but protein and lactose concentrations were unaffected. With the higher proportion of fibrous concentrates (80F), milk yield and the protein and lactose concentration were similar to values on 60F but fat concentration was lower, though not nearly so low as on 80S. Milk energy yield was reduced by the higher proportion of concentrates but was unaffected by type of carbohydrates. Live-weight changes were small.In both the sheep, consuming at maintenance, and the lactating cows consuming at about 3 times maintenance, digestibility of dry matter, organic matter and energy was higher with the higher concentrate diets but was unaffected by type of concentrate. The digestibility of fibre was greater with the fibrous concentrates but the effect of level of concentrate inclusion was inconsistent. Digestibility coefficients were consistently lower for the lactating cows than for the sheep.The proportion of acetic acid in the rumen volatile fatty acids in the cows was higher and the proportion of propionic acid was lower with the fibrous concentrates. The differences were much greater with the higher proportion of concentrates.During weeks 15–22 of lactation the cows were reallocated to concentrate treatments and given hay ad libitum. Hay intake was about 1 kg/day higher with the fibrous concentrates but the difference was not significant. Hay intake fell by about 0·6 kg/kg concentrate intake for both concentrate types. No significant differences in milk yield or composition were established, probably because of incomplete adaptation even after 8 weeks.It is concluded that at concentrate intakes of about 10 kg/day, the source of carbohydrate in the concentrates has little effect on milk production when the concentrates are of similar ME concentration. However, at higher levels of concentrate inclusion, although the diets may have similar ME concentrations, important differences in the yields of fat, protein and lactose occur due to carbohydrate source and these can be related to differences in rumen fermentation.

PSIV-B-25 Digestible energy and metabolizable energy of high-fiber ingredients in growing pig diets

2021 ◽  
Vol 99 (Supplement_3) ◽  
pp. 394-395
Author(s):  
Jongkeon Kim ◽  
Yun Yeong Jo ◽  
Beob Gyun G Kim
Keyword(s):  
Latin Square ◽  
Basal Diet ◽  
Growing Pigs ◽  
Metabolizable Energy ◽  
Adaptation Period ◽  
Digestible Energy ◽  
High Fiber ◽  
Cashew Nut ◽  
Growing Pig ◽  
Gluten Feed

Abstract The objective of this study was to determine the digestible energy (DE) and metabolizable energy (ME) concentrations in high-fiber ingredients fed to growing pigs. Twelve barrows with an initial body weight of 57.5 kg (SD = 5.7) were individually housed in metabolism crates. A replicated 6 × 3 incomplete Latin square design with 12 animals, 6 experimental diets and 3 periods was employed. A basal diet was composed of 75.0% corn and 22.7% soybean meal (SBM) as the sole energy sources. Four experimental diets were prepared by replacing 40% of corn and SBM with soybean hulls (SH), corn gluten feed (CGF), wheat bran (WB), or rice bran (RB). An additional diet was prepared by replacing 10% of corn and SBM with cashew nut hulls (CNH). Each period consisted of a 4-d adaptation period and a 4-d collection period, and the marker-to-marker procedure was used for total collection of feces and urine. The DE and ME values in RB (3,969 and 3,936 kcal/kg DM) were greater (P &lt; 0.05) than those in CGF (2,654 and 2,520 kcal/kg DM) and SH (2,492 and 2,541 kcal/kg DM) and the energy values in WB (3,162 and 3,118 kcal/kg DM) were not different from those in RB, CGF, or SH. The DE and ME values in CNH (350 and 572 kcal/kg DM) were less (P &lt; 0.05) than those in all other test ingredients. In conclusion, energy concentrations in RB were greatest among the high-fiber test ingredients, whereas CNH had the lowest values.

The associative effect of level of energy and protein intake in the dairy cow

1970 ◽  
Vol 37 (3) ◽  
pp. 481-491 ◽  
Author(s):  
F. J. Gordon ◽  
T. J. Forbes
Keyword(s):  
Energy Intake ◽  
Milk Yield ◽  
Protein Level ◽  
Protein Intake ◽  
Latin Square ◽  
Metabolizable Energy ◽  
Energy Output ◽  
Additional Energy ◽  
Protein Nitrogen ◽  
Low Protein

SummaryEight lactating cows were used in a Latin square experiment, to study the associative effects of level of energy and protein intake on milk yield and composition. Four diets were used, supplying 80 and 120% of estimated energy requirements and 80 and 120% of estimated protein requirements. The level of energy intake significantly affected milk yield, milk energy output, percentage butterfat, ash and non-protein nitrogen. The level of protein intake only significantly affected milk energy output and the non-protein nitrogen content of the milk. Although only the interaction of the effects of energy and protein intake on the milk content of solidsnot-fat (SNF) and ash was significant, it was evident that the effect of each of these factors on milk yield or composition was related to the level of the other in the diet.Input-output relationships within each protein level were used to compute the response in milk energy output and bodyweight change to a change in energy intake. These showed a greater partitioning of additional energy toward milk energy output with the high than with the low protein level. Multiple regression analysis within each level of protein intake was used to partition energy intake between that used for maintenance, milk energy output and liveweight change. The results showed efficiencies of utilization of metabolizable energy for milk output of 63 and 50% on the high- and low-protein diets, respectively.Nitrogen balance data are presented.

scholarly journals Effect of different levels of supplied cobalt on the fatty acid composition of bovine milk

2012 ◽  
Vol 109 (5) ◽  
pp. 834-843 ◽  
Author(s):  
Inger J. Karlengen ◽  
Ole Taugbøl ◽  
Brit Salbu ◽  
Are H. Aastveit ◽  
Odd M. Harstad
Keyword(s):  
Milk Yield ◽  
Feed Intake ◽  
Milk Fat ◽  
Bovine Milk ◽  
Latin Square ◽  
Basal Diet ◽  
Cobalt Acetate ◽  
Linear Effect ◽  
Fa Composition ◽  
Four Levels

In previous studies, administration of high amounts of Co decreased the proportion of MUFA in bovine milk. The present study was conducted to examine the amount of Co needed to obtain this effect. High-yielding dairy cows (n4), equipped with ruminal cannulas, were used in a 4 × 4 Latin square design study. The basal diet consisted of concentrate mixture (9 kg/d) without added Co and grass silage (ad libitum). The following four levels of Co were administrated as cobalt acetate dissolved in distilled water: no Co (treatment 1, T1); 4·0 mg Co/d (T2); 380 mg Co/d (T3); 5300 mg Co/d (T4). Each period lasted for 18 d, including 11 d of treatment. During the treatment periods, the solutions were continuously infused into the rumen. Milk yield and milk concentration of fat, fatty acids (FA), protein, lactose, Co, Zn, Fe and Cu were determined. Blood plasma was analysed with respect to FA, Co, Zn, Fe and Cu. Feed intake and total tract digestibility of feed components were also determined. There was a linear effect of increasing the level of Co on milk FA composition. The effects of Co on FA composition in blood were insignificant compared with the effects on milk. In milk fat, the concentration ofcis-9-18 : 1 was reduced by as much as 38 % on T4 compared with T1. Feed intake and milk yield were negatively affected by increasing the Co level.

scholarly journals Digestibility of amino acids, energy, acid hydrolyzed ether extract, and neutral detergent fiber, and concentration of digestible and metabolizable energy in low-oil distillers dried grains with solubles fed to growing pigs1

2019 ◽  
Vol 3 (2) ◽  
pp. 662-675 ◽  
Author(s):  
Charmaine D Espinosa ◽  
Su A Lee ◽  
Hans H Stein
Keyword(s):  
Amino Acids ◽  
Body Weight ◽  
Latin Square ◽  
Basal Diet ◽  
Metabolizable Energy ◽  
Neutral Detergent Fiber ◽  
Ether Extract ◽  
Initial Body Weight ◽  
Distillers Dried Grains ◽  
Gross Energy

Abstract Two experiments were conducted to test the hypothesis that digestibility of amino acids (AA), gross energy (GE), acid hydrolyzed ether extract (AEE), and neutral detergent fiber (NDF), and values for metabolizable energy (ME) in low-oil distillers dried grains with solubles (DDGS) vary among suppliers. In Exp. 1, the apparent total tract digestibility (ATTD) of GE, AEE, and NDF, and concentration of ME were determined in eight sources of DDGS (sources A, B, C, D, E, G, H, and I). A corn-based basal diet and eight diets containing corn and each source of DDGS were fed to 72 barrows (initial body weight = 18.1 ± 1.3 kg) with eight pigs per diet. Feces and urine were collected for 5 d after 7 d of adaptation. The ME did not differ among the eight sources of DDGS with the exception that DDGS source E contained less (P &lt; 0.05) ME than DDGS source D. The ATTD of GE did also not differ among the eight sources of DDGS, but ME and ATTD of GE in corn were greater (P &lt; 0.05) than in the eight sources of DDGS. However, the ATTD of AEE in corn and the eight sources of DDGS was not different, but the ATTD of AEE in DDGS source E was greater (P &lt; 0.05) than in DDGS source A. The ATTD of NDF in DDGS source D was also greater (P &lt; 0.05) than in DDGS sources E, G, and H, but ATTD of NDF did not differ between corn and the eight sources of DDGS. In Exp. 2, standardized ileal digestibility (SID) of AA was determined in seven sources of DDGS (sources A, B, C, D, E, G, and H). Twenty-four barrows (initial body weight = 63.4 ± 3.4 kg) that had a T-cannula installed in the distal ileum were allotted to a two-period incomplete Latin square design with eight diets. Seven diets were formulated to contain each of the seven sources of DDGS and an N-free diet was also used. Ileal digesta were collected for 2 d after 5 d of adaptation. There were no differences between pigs fed DDGS sources A and B in SID of AA, and the SID of Lys, Met, and Trp did not differ among DDGS sources A, B, and E. However, SID of most indispensable and dispensable AA except Gly were greater (P &lt; 0.05) in DDGS source B than in DDGS sources C, D, E, G, and H. In conclusion, variability in SID of AA, ATTD of NDF and AEE, and ME were observed among the sources of DDGS used in this experiment.

scholarly journals Protein and energy metabolism of lactating Granadina goats

1990 ◽  
Vol 63 (2) ◽  
pp. 165-175 ◽  
Author(s):  
J. F. Aguilera ◽  
C. Prieto ◽  
J. FonollÁ
Keyword(s):  
Milk Yield ◽  
The Body ◽  
Metabolizable Energy ◽  
Positive Energy ◽  
Energy Yield ◽  
Regression Equations ◽  
Total N ◽  
Lactating Goats ◽  
Energy Retention ◽  
Body Energy

Twelve goats of the Granadina breed in mid- and late lactation were used in two consecutive years to determine their protein and energy requirements for lactation. The animals were individually fed on diets based on pelleted lucerne (Medicago sativa) hay and barley. A total of six balance experiments were carried out. Gas exchange was measured using open-circuit respiration chambers. Milk yield ranged widely from 0.649 to 1.742 kg/d in the first year and from 0.222 to 1.989 kg/d in the second year, a steady decline in milk output being observed as lactation progressed. Milk composition remained rather constant during the midstage of lactation, with an average content (/kg milk) for total solids, total nitrogen, fat and gross energy of 149.7 g, 5.39 g, 58.8 g and 3.59 MJ respectively. Total endogenous N, endogenous urinary N and maintenance requirement for N in lactating goats were estimated to be 244, 218 mg N/kg body-weight (W)0.75 per d and 478 mg total N/kg W0.75 per d respectively from regression equations. A constant efficiency of use of dietary N for milk N plus retained N of 51.0 % was found. By regressing milk energy plus apparent body energy retention or loss on metabolizable energy (ME) intake, the maintenance energy requirement was estimated to be 401 kJ ME/kg W0.79 per d. When estimating the corrected milk yield as milk energy +(0.84 x negative energy retention) +(1.05 x positive energy retention), regression analysis indicated that the overall efficiency of use of ME for lactation was 66.7%. Also, from a plot of apparent body energy retention v milk energy yield, both expressed as a percentage of ME intake above maintenance, the efficiency with which ME was used to promote energy retention in the body during lactation was calculated to be 0.907 times that for milk secretion.

The effect in ewes of source and level of dietary protein on milk yield, and the relationship between the intestinal supply of non-ammonia nitrogen and the production of milk protein

1982 ◽  
Vol 34 (1) ◽  
pp. 31-40 ◽  
Author(s):  
J. S. Gonzalez ◽  
J. J. Robinson ◽  
I. McHattie ◽  
C. Fraser
Keyword(s):  
Milk Yield ◽  
Blood Meal ◽  
Plasma Concentrations ◽  
Basal Diet ◽  
Ammonia Nitrogen ◽  
Soya Bean ◽  
Metabolizable Energy ◽  
Yield Response ◽  
Protein Nitrogen ◽  
True Protein

ABSTRACTIndividually penned Finnish Landrace × Dorset Horn ewes in early lactation, and each suckling two lambs, were used to test the effects on milk yield, milk composition and the concentrations of some plasma constituents of supplementing a basal diet with either urea, groundnut, soya bean, linseed, fish, meat and bone, or blood meal. The basal diet contained 94 g crude protein and 10 MJ of metabolizable energy per kg dry matter and supplied daily 0·3 MJ of metabolizable energy per kg body weight. Except for urea, which was tested at an inclusion rate that increased the protein (nitrogen × 6·25) content of the basal diet by 43 g/kg, the remaining sources were tested at three levels, corresponding to increases in protein content of 34,60 and 86 g/kg. Daily milk yields were 1·92 and 2·08 kg for ewes given the basal diet and the basal diet supplemented with urea. For the high inclusion rates of each protein source the following daily yields were obtained (kg): groundnut, 2·26; soya bean, 2·45; meat and bone, 2·49; linseed, 2·68; fish, 2·84; and blood meal, 2·91. The daily yields of true protein in milk were (g): basal diet, 76; basal diet plus urea, 80; groundnut, 104; soya bean, 107; meat and bone, 105; linseed, 112; fish, 136; and blood meal, 125. Plasma concentrations of free fatty acids did not appear to support the hypothesis that the milk yield response to protein is accomplished solely by increases in tissue energy loss.The increment in the amount of non-ammonia nitrogen reaching the abomasum as a result of the low levels of inclusion of the protein sources in the basal diet was used for the production of true protein-nitrogen in milk with an efficiency of 0·58.

scholarly journals PSVII-36 Late-Breaking Abstract: Protein concentrations in basal diets affect metabolizable energy of feed ingredients determined by difference procedure in pigs

2020 ◽  
Vol 98 (Supplement_4) ◽  
pp. 340-341
Author(s):  
Hansol Kim ◽  
Jung Yeol Sung ◽  
Beob G Kim
Keyword(s):  
Soy Protein Isolate ◽  
Latin Square ◽  
Basal Diet ◽  
Protein Isolate ◽  
Metabolizable Energy ◽  
Energy Output ◽  
Feed Ingredients ◽  
Low Protein ◽  
Gross Energy ◽  
The Difference

Abstract The objective was to investigate the influence of crude protein (CP) concentrations in the basal diet on the metabolizable energy (ME) of feed ingredients determined using the difference procedure in pigs. Twelve barrows (73.7 ± 5.5 kg body weight) individually housed in metabolism crates were used. A low-protein basal diet (LPBD, 7.4% CP) was composed of 97.5% corn as the sole energy source and a high-protein basal diet (HPBD, 14.3% CP) was composed of 78.0% corn and 19.6% soybean meal. Four additional diets were prepared by replacing 20% of the energy sources in the basal diets with full-fat soybean (FFSB, 37.7% CP) or soy protein isolate (SPI, 87.6% CP). The 6 experimental diets were fed to 12 pigs employing a replicated 6 × 4 incomplete Latin square design with 4 periods. Each period was consisted of 4 days of adaptation and 4 days of collection period and the marker-to-marker method was used for fecal collection. Urinary gross energy output was greater (243 vs. 176 kcal/d; P &lt; 0.05) in the HPBD group compared with the LPBD group. While ME in the HPBD was greater (3,418 vs. 3,322 kcal/kg; P &lt; 0.05) than in the LPBD, ME in FFSB diets (3,585 and 3,633 kcal/kg in the LPBD and HPBD group, respectively) and SPI diets (3,537 and 3,537 kcal/kg, respectively) were not different between the 2 basal diet groups. Metabolizable energy of the test ingredients was less (P &lt; 0.05) in pigs fed the HPBD group (4,565 and 4,111 kcal/kg in FFSB and SPI, respectively) compared with pigs fed the LPBD group (4,756 and 4,517 kcal/kg in FFSB and SPI, respectively). In conclusion, as the protein in the basal diet increases, metabolizable energy in a test ingredient determined using the difference procedure decreases mainly due to greater urinary energy output in pigs.

71 Evaluation of the CVDS Beef Cow Model to Estimate Biological Efficiency in Mature Cows

2021 ◽  
Vol 99 (Supplement_1) ◽  
pp. 119-119
Author(s):  
Phillip A Lancaster ◽  
Mike Davis ◽  
Luis O Tedeschi ◽  
Jack Rutledge ◽  
Larry Cundiff
Keyword(s):  
Milk Yield ◽  
Feed Intake ◽  
Pearson Correlation ◽  
Correlation Coefficients ◽  
Metabolizable Energy ◽  
Biological Efficiency ◽  
Production Cycle ◽  
Energy Yield ◽  
Weaning Weight ◽  
Beef Cow

Abstract There is no clear method to measure biological efficiency in grazing beef cows. The objective of this study was to evaluate a nutrition model to estimate biological efficiency in mature cows. Data from dams (n = 160) and their 2nd and 3rd progeny were collected from 1953 through 1980. Individual feed intake was measured at 28-d intervals for lifetime of dams and during 240-d lactation for progeny. Body weight of progeny were measured at birth and weaning, and dams at parturition and weaning each production cycle. Milk yield of dams was measured at 14-d intervals by hand milking. Metabolizable energy required (MER) and predicted milk energy yield (MEY) of each cow was computed using the CVDS beef cow model for each parity. Biological efficiency was computed as the ratio of cow ME intake (MEI) to calf weaning weight (WW) based on observed (MEI/WW) and predicted (MER/WW) values. Pearson correlation coefficients were computed using corr.test function in R software. Average (SD) cow weight, calf weaning weight, cow MEI, and observed MEY were 507 (81) and 548 (88) kg, 287 (49) and 294 (44) kg, 9406 (2695) and 9721 (2686) Mcal, and 1009 (538) and 1051 (521) Mcal, for progeny 2 and 3, respectively. Cow MEI and MER (0.87 and 0.85), and observed and predicted MEY (0.51 and 0.51) were positively correlated for progeny 2 and 3, respectively. The CVDS model under predicted cow MEI [mean bias = 1685 (1718) and 1658 (1702) Mcal] and MEY [mean bias = 82 (465) and 129 (450) Mcal] for progeny 2 and 3, respectively. Observed and predicted progeny feed intake were not correlated. Observed and predicted biological efficiency were positively correlated (0.63 and 0.61) for progeny 2 and 3, respectively. In conclusion, nutrition models can reasonably predict biological efficiency, but further refinement of the relationship between calf feed intake and milk yield could improve prediction.

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