Starch Equivalent Research Articles

Prediction of the useful energy in tropical feeds from proximate composition and in vivo derived energetic contents. 2. Starch equivalents

Starch equivalent (SE) values of 345 tropical forages and 37 concentrates derived from digestibility experiments with sheep and cattle formed the data set. Through multiple regression analyses, SE was related to linear, quadratic and cubic terms of the nutrients CP, ether extract (EE), crude fibre (CF), NFE and ash as independent variables. The models were assessed by coefficient of determination ( R 2) and practicality. Under these conditions the following prediction equations were recommended: (a) forages: SE (%) = − 19.48 + 1.4329CP + 2.4494EE + 0.8083NFE; R 2 = 0.46, P < 0.0001, RSD = 6.89%; SE (%) = 134.70 − 1.5703CF − 0.7180NFE − 1.4327ASH; R 2 = 0.45, P < 0.0001, RSD = 6.94%; SE (%) = 65.11 + 0.7427CP − 0.8789CF − 0.7301ASH; R 2 = 0.44, P < 0.0001, RSD = 6.99%; SE (%) = 71.48 − 1.1155CF; R 2 = 0.33, P < 0.0001, RSD = 7.65% (b) concentrates: SE (%) = − 36.46 + 6.1478CF − 0.64 14CF 2 + 0.0158CF 3 + 7.7236NFE −0.1649NFE 2 + 0.0010NFE 3; R 2 = 0.67, P < 0.0001, RSD = 7.76%; SE (%) = 80.15 − 1.2200CF + 1.1005EE; R 2 = 0.42, P < 0.0001, RSD = 10.30%. Crude fibre had a strong influence in the prediction of SE, although it was preferable to predict SE using a combination of nutrients because of a substantial increase in R 2. It was concluded that SE may be estimated using our predictors to within a range of ± 8.8 to 9.8% for tropical forages and to within ± 9.9 to 13.2% for concentrates with a probability of 80%. This level of accuracy was considered high given the diverse nature of the feeds and the wide tropical area for which the predictors may be applied.

ESTIMATION OF HAY ENERGY VALUE WITH A REGRESSION EQUATION

825 random samples of hay, 655 the first cut and 170 aftergrass, were analysed according to Weende analysis. The results were accounted with the statistical package SPSS so that multiple regessions were calculated for the starch equivalent (SE) and net energy for lactation (NEL) for all samples and separately for the first cut and aftergrass respect. The equations were carried out with the stepwise inculding the separate nutrients. All multiple regression coefficients (R) were very higly significant. For the first cut samples, the estimation of SE on the base of all nutrients was very accurate (R=0.9796, s.e.=1.4502). For the practice, it is sufficient to estimate it with the crude fibre (CF) and crude protein (CP) contents only (R=0.9613, s.e.=1.9861). In the case of estimation of NEL it is necessary to take into account all nutrients (R=0.9429, s.e.=0.1822). It is possible to estimate SE well with all nutrients (R=0.95488, s.e.=0.14164) in afftergrass. For NEL CP, ether extract and nitrogen-free extractives (R=0.93487, s.e.=0.14164) are sufficient. When the samples are not defined, SE and NEL should be estimated with all nutrients (R=0.97186, s.e.=1.69134 resp. R=0.95646, s.e.=0.15974).

CHEMICAL COMPOSITION AND NUTRITIVE VALUE OF GRASS, CONSERVED BY VARIOUS METHODS

Chemical composition, apparent digestibility, degradability of dry matter and crude protein in the rumen at 1.5, 3, 6, 12, 24 and 48 hours after incubation, and the effective degradability of crude protein and nutritive value were established in deep frozen grass and in silages, made from unwilted grass, unwilted grass conserved with 0.4 % EnsimaxÒ , and wilted grass. When fresh unwilted grass (201 g per kg DM) was ensiled very carefully in 1 m3 silos, no significant differences in chemical composition, degradability, apparent digestibility and nutritive value were observed in comparison to silage conserved with EnsimaxÒ . Silage from wilted grass was significantly less digestible and had 17 % less digestible crude protein (DCP), starch equivalent (SE) and NEL (MJ) per kg DM compared to silage from unwilted grass.

Effects of periodic feed restriction with subsequent re-alimentation on performance of Baladi goats

In a study over 105 days, sixteen bucks, averaging 21.5 kg, in four groups of four animals each, received a diet of wheat straw (WS) and concentrate mixture (CM) to meet maintenance requirements. Wheat straw was to cover one fourth of the required energy in starch equivalents (SE). Group 1 (control), was fed WS + CM during the experiment. Groups 2, 3 and 4 were periodically deprived of CM and fed WS only for 5, 10 or 15 days of deprivation periods. Thereafter, they were returned to the whole diet for a 10-day re-alimentation period. Body weights decreased as the period of restriction lengthened, and were approximately 8% in group 3 for 10 days restriction and 10 days re-alimentation, compared to controls. These goats consumed 50% less concentrates than the controls without apparent harmful effects. Digestion coefficients for group 3 seemed higher than in the other treatments and nitrogen retention appeared to be better. Values of plasma protein and neutral N-balance suggested that 10-day restricted goats did not suffer from insufficient protein intake.

The me system : The biological basis

The Starch Equivalent (SE) system devised by Kellner for expressing the energy requirements of ruminants and the energy value of feeds was used in Britain from 1912. Metabolizable energy (ME) was proposed (Agricultural Research Council, 1965) and adopted (MAFF, DAFS and DANI, Technical Bulletin 33, 197S), as a basis for a new system relating diet to the energy requirements of animals. Additional information was incorporated in the extensive Technical Review (The Nutrient Requirements of Ruminant Livestock, 1980). Metabolizable energy was retained, and animal performance it was claimed, was predicted more precisely with ME than SE. Results presented in this paper are for the comparison, and interpretation, of observed and predicted (Technical Bulletin 33) rates of gain, and other components of the ME system, for growing lambs and cattle fed forage and mixed forage and concentrate diets.

Estimation of digestibility, metabolizable energy and net energy of forage by a cellulase method

As an alternative to existing methods for digestibility determination using rumen juice, a cellulase method is proposed for routine use, which is easy, cheap and sufficiently precise. From material comprising 47 green and preserved forages of known digestibility in vivo regression equations have been derived for the estimation of the organic matter digestibility, the metabolizable energy, the net energy-fat (NEF r) and the starch equivalents.

Some thoughts on amino acid supplementation of proteins in relation to improvement of protein nutriture.

Supplementation of diets with free amino acids has not routinely been beneficial and poses a potential risk. Thus, mixing proteins to increase the quality of the dietary protein is attractive. The slope-ratio technique for evaluation of protein quality has serious drawbacks, because the growth response is not linear and animals appear to adapt to the diet and thus make more efficient use of diets low in protein or low in protein quality. Apparently, the relative value of proteins is not constant, but varies with the amino acid spectrum as well as intake. Thus, evaluation of proteins or protein mixtures should be determined under the conditions (e.g. maintenance or maximum gain) of their potential use. This approach could lead to the development of a protein replacement equivalents system similar to the starch equivalents system in the evaluation of the net energy of animal feeds.

Estimation of the net energy using volatile acids produced in the process of in-vitro digestion with ruminal fluid

47 types of green feeds and roughages were subjected to an in-vitro fermentation with dilute ruminal fluid. The volatile fatty acids produced in this process were determined quantitatively in accordance with the method of digestibility estimation proposed by Tilley and Terry (1963). An average of 5 Mol FFS (FFS=volatile fatty acids) was found per kg of dried feed, a value is also reported in the literature. The ratios of acetate to propionate to n-butyrate to iso-butyrate to n-valerianate were 64.2 : 25.4 : 6.6 : 0.8 : 1.5 : 1.5. In this ratio, propionic acid predominated so that acetic acid and n-butyric acid were misrepresented compared with the data of in-vivo measurements made for the corresponding foodstuffs. Consequently, it is only within certain limits that values of FFS concentrations obtained in vitro may be used for estimating net energy data, disregardful of the fact that the FFS are the main source of metabolizable energy in ruminants. The reliability index for an estimation of Starch Equivalents and NEFr based on the above-mentioned method was found to be considerable lower (0.71 and 0.80) than that based on in-vitro digestibility measurements (0.86).

Effect on production and carcass quality characteristics of wether lambs of crossing Blackheaded Mutton, Ile de France and Texel rams with Polish Merino ewes

During the period 1972–1974 investigations were made on 120 wethers fattened semi-intensively to a weight of 45 kg liveweight. These lambs originated from commercial crosses of the Polish Merino with rams of the breeds Blackheaded Mutton (B), Ile de France (IF) and Texel (T) as well as pure Merino (M) in the control group. The use of rams of these meat-producing breeds as compared with Merino gave a better growth rate: an increase in the group IF × M of 6.2%, B × M of 7.8% and T × M of 8.8% respectively. The feed consumption, expressed in starch equivalents per kg of weight, decreased in group IF × M by 11.6%, B × M by 15.1% and T × M by 15.6%, and total digestible protein decreased in the group IF × M by 12.1%, B × M by 16.6% and T × M by 16.9%. Crosses with Blackheaded Mutton and Ile de France rams did not fundamentally change the tissue composition of the lamb carcasses. However, the use of Texel rams resulted in carcasses with a higher lean content and less fat as compared with pure Merino (difference 5.7%) as well as with other crosses (differences 4.2–4.8%). Rams of the meat breeds tested did not greatly influence dressing percentage and carcass yield in terms of bone content and the proportion of valuable cuts; nor were dimensions affected, except for a decrease in length of 2–3.5% compared with Merino.

Dried sugar beet pulp as a high energy feed for beef cattle

Digestibility trials with 8 lots of pelleted dried sugar beet pulp, carried out with wethers, demonstrated that dried sugar beet pulp is a highly digestible energy source for ruminants. From the digestion coefficients obtained, and a value number of 95, the starch equivalent of the dry matter of dried sugar beet pulp was calculated to be 73.3, while the net energy expressed in EF r was 619 EF r per kg dry matter. This is about 90% of the net energy content of barley containing 4% crude fibre in the dry matter. Beef production trials were carried out with 702 young bulls fed on complete dry rations based on dried sugar beet pulp. Two categories of animals were used: 322 baby-beef bulls (intensive system) slaughtered at 13 months of age at an average live-weight of 480 kg; and 380 young bulls coming from pasture (semi-intensive system) at about 250 kg live-weight, and fattened indoors up to at least 550 kg live-weight. With each category, three different rations have been studied. These contained respectively, 50, 60 or 70% pelleted dried sugar beet pulp; the remainder of the rations consisted of respectively 50, 40 or 30% concentrates. The diets were fed ad libitum; straw and water were always available. The three complete dry rations proved to be equally successful for intensive beef production. The carcass quality was good for all animals. The average daily gain obtained with the baby-beef bulls for the three rations respectively was 1 207 g, 1 274 g and 1 172 g; for the second category of bulls the mean growth rates were generally slightly higher: 1 281 g, 1 309 g and 1 357 g. The feed efficiency was higher with the younger animals: the baby-beef bulls (live-weight interval: 150–480 kg) consumed about 2.5 kg protein supplement and 3.5 kg dried sugar beet pulp per kg live-weight gain; while the intake per kg live-weight gain with the bulls of the second category (live-weight interval: 250–560 kg) amounted approximately to 2.75 kg protein supplement and 4 kg dried sugar beet pulp. Within each category of bulls, the feed cost per kg live-weight gain decreased with increasing amounts of dried sugar beet pulp in the rations.

Maize grain or ears in concentrate diets for young fattening bulls

An experiment was conducted to test the effect of partial or total substitution of ground maize grain with ground ear maize in complete mixtures for the fattening of young bulls. Animals of the control group (Group 1) received ground maize as the main ingredient of the concentrate mixture, those of Group II, ground maize and ground ear maize, and animals of Group III, ground ear maize. Increasing crude fibre in the rations by the addition of ground ear maize significantly decreased dry matter digestibility and increased digestibility of crude fibre. Bulls fed on ground maize achieved the highest daily gain which was significantly higher, by 6.62%, than that of the animals given ground ear maize, and by 3.45% compared to the ration based on ground maize and ground ear maize. Feed conversion per kg of live weight gain (LWG) was similar to daily consumption and it was higher in animals fed on the ground ear maize ration, by 16.95%, compared to those fed on ground maize, and by 8.15% compared to the animals fed on the combined ration. Both differences were statistically significant. Conversion of starch equivalent (SE) showed that the only significant difference was that between animals fed on the ground maize mixture and those fed on the ground ear maize mixture. Conversion of protein depended directly on the amount of feed consumed and the differences of 99 and 57 g per kg of LWG, which were significant, could be attributed to higher consumption of the mixtures based on ground ear maize.

Investigations into the relationship of selected blood components to nutrition and fertility of the dairy cow under commercial farm conditions.

Blood chemistry, nutrition, productivity and fertility were monitored and their interrelationship examined in groups of cows from 15 commercial dairy herds. Plasma urea, albumin, glucose, non-esterified fatty acids (NEFA), acetone, calcium, magnesium, inorganic phosphorus (IP), blood copper, haemoglobin and packed cell volume were examined in relation to the intakes of starch equivalent (SE) digestible crude protein (DCP), calcium, phosphorus, magnesium, sodium, potassium, copper and manganese. The most consistent correlations were found for the regressions of SE intake as a percentage of requirements (I/R per cent) on plasma non-esterified fatty acids, the ratio of SE intake over DCP intake on plasma urea, DCP I/R per cent on plasma urea and phosphorus I/R per cent on plasma IP, but factors other than nutrition accounted for a large part of the variation in all cases. The mean plasma glucose concentration within +/- three days before or after first service of cows which held was higher than that of cows which returned, but the difference was only approaching significance at the 5% level and it is doubtful whether it could be of practical value. No other differences in blood component levels were demonstrated for first or second service. It is concluded that, within the nutritional ranges encountered, the levels of the selected blood components did not show a consistent relationship to nutrient balance or potential fertility. In this context a multiple analytical scheme employing these components would appear to be of limited value, particularly if samples are taken on only one occasion. The technique is more appropriately regarded as an aid to the conventional approach involving the examination of feeding systems and feedstuffs, herd records, management and clinical conditions.

The relative value of concentrates and roughage for fattening cattle

SUMMARYIn three similar experiments, 2 or 3 kg of a commercial concentrate mixture, forming part of a high concentrate ration, were replaced by an equal weight of dry matter of one of four roughages: hay, straw, silage and green soilage.The metabolizable energy content of the concentrate was 2-4 Mcal/kg. Expected daily gain was calculated according to the following energy systems: Scandinavian feed units (SFU), starch equivalent (SE), total digestible nutrients (TDN), the U.K. Agricultural Research Council system (ARC), and the U.S. National Research Council net energy system (NRC).The replacement of 2 kg of concentrate significantly reduced daily gain only in the straw treatment. Reduction of the fat content of the carcasses was significant for all roughage treatments. The differences between the observed daily gain and the expected, as calculated by the SFU, SE and NRC systems, were highly significant, while those between the observed and those cal culated by the TDN and ARC systems were not significant. The TDN system overestimated the nutritional value of the roughages, while the SFU and SE systems underestimated it.

The nutritive value for ruminants of a complete processed diet based on barley straw

SUMMARYCalorimetric experiments were made with a complete extruded diet for ruminants, ‘Ruminant Diet A’ prepared by Messrs U.K. Compound Feeds Ltd. Twelve determinations of energy and nitrogen retention were made using sheep and it was found that the diet had a metabolizable energy value of 2–32 kcal/g organic matter, and the net availabilities of its metabolizable energy were 42–7 % for fattening and 68–0 % for maintenance. These values agreed well with those predicted from equations published by the Agricultural Research Council. On a dry basis the starch equivalent was 38–3 %.

Nutritive values and chemical composition of seven tropical legumes and lucerne grown in subtropical south-eastern Queensland

The chemical composition and feeding value of seven tropical legumes and lucerne were determined by pen feeding experiments with sheep. Most of the legumes were harvested during autumn and winter. Lucerne had the highest feeding value and the highest values for the tropical legumes were obtained for Vigna vexillata, Lotononis bainesii, and Desmodium uncinatum. After frosting, the feeding values of Phaseolus lathyroides and Vigna vexillata were reduced but that of Desmodium uncinatum was not changed. This may have been due to a greater loss of leaf by both P. lathyoides and V. vexillata than by D. uncinatum. Frost did not affect Lotononis bainesii and Medicago sativa, and both had a higher feeding value than the legumes affected by frost. The usefulness of crude protein and crude fibre for estimating dry matter digestibility and dry matter intake and the relation between dry matter digestibility and dry matter intake is discussed. The use of dry matter digestibility to express the nutritive value of feed energy in preference to organic matter digestibility, starch equivalents, and total digestible nutrients is also discussed.

The effect of feeding dried sugar-beet pulp on the intake and production of dairy cows

SummaryThree rations were compared in a 15-week winter feeding experiment using 12 Ayrshire cows. All the cows received silage 3 times a day and concentrates; ration A contained no sugar-beet pulp whilst ration B contained 6 lb of pulp and ration C 12 lb.The total weights of dry matter consumed were 29·7, 32·3 and 33·4 lb/day, respectively, on treatments A, B and C. For every 1 lb of extra sugar-beet pulp dry matter eaten the decline in the dry weight of the other feeds consumed was 0·50 lb on treatment B and 0·55 lb on treatment C. The main decrease was in the silage part of the ration. The weights of starch equivalent (S.E.) consumed daily were 18·0, 19·8 and 20·7 lb on rations A, B and C, respectively, with mean daily milk yields of 38·2, 39·3 and 39·7 lb, giving a response of 0·55 lb milk/lb extra S.E. between rations A and C. The corresponding fat percentages of the milks did not differ significantly from each other but the solids-not-fat (SNF) percentages increased significantly from 8·76% on ration A to 8·88% on ration C. The average response per lb extra S.E. was 0·044% SNF and the increase was in the protein fraction of the milk. The cows were significantly heavier on rations B and C than on ration A. The inclusion of beet pulp in rations B and C had no adverse effect on the taste of the milk.

OBSERVATIONS ON THE UTILIZATION OF GRASS GRAZED BY YOUNG BEEF CATTLE WITH AND WITHOUT BARLEY SUPPLEMENTATION

A field trial was carried out in which 3 groups of cattle were grazed on a paddock system with and without supplementary barley. The cattle were 6 months old when turned out to grass and were each fed 4 lb/day of barley for one week to prevent any adverse effect from an abrupt change of diet. The trial began on 14 May and continued until 8 October. The mean liveweight gain obtained on the unsupplemented grass was only 0·97 lb/day up to 20 August and owing to the poor growth of the animals a supplement of 4 lb barley/head/day was then introduced. The daily liveweight gain for the remainder of the trial was 1·94 lb. When a supplement of 4 lb barley was provided throughout the trial the mean daily liveweight gain was 1·61 lb. When barley was fed ad lib. intake averaged 12·3 lb/head/day throughout the trial and the mean daily gain was 2·45 lb.Indoor digestibility and nitrogen retention trials were carried out. The starch equivalents of diets on the three treatments were 63·7, 68·3 and 69·5, respectively. The respective mean daily intakes of dry matter were 11·2, 11·9 and 11·8 lb, and the mean daily retentions of N were 35·0, 35·8 and 33·6g. These results indicate that although the grass was of good nutritive value the poor performance of the animals on grass alone was mainly due to their inability to graze sufficient grass.

Losses in the conservation of grassland herbage in lined trench silos:I. A comparison of long and lacerated silages made by the warm fermentation process

A conservation experiment is described in which a comparison is made of quality and of nutrient losses in long and lacerated silages of warm fermentation type made in large lined trench silos. High losses of 29.5 and 34.7% of the dry matter in the long grass silages and 32.8 and 32.4% in the lacerated silages were recorded. Losses of starch equivalent were correspondingly high amounting to 43.3 and 49.5% in the long grass silages and 49.1 and 46.5% in the lacerated silages. The mean loss of dry matter in the effluent from the lacerated silages was 1.3% higher than in the long grass silages.

A comparison of the feeding value of maize and sorghum for fattening pigs

Six comparable groups, each of 4 castrate pigs, were used to compare the feed value of maize and sorghum as estimated by live-weight gain, food conversion efficiency, slaughter quality and ham composition.The maize ration contained 40% yellow maize and the sorghum ration 40% Sorghum vulgare subglabrescens, all other ingredients being the same for both diets.No statistically significant differences were found between the maize and sorghum pigs with regard to the criteria mentioned.It is concluded that no difference exists between the feed value of the maize and the sorghum used. This result is in better agreement with the net energy values of maize and sorghum as calculated by the formula of Hoff-mann and digestion coefficients for pigs, than with “classical” starch equivalents.

Establishment studies V. The effect of method of establishment on the behaviour of long-term leys in the seeding year

1. In the seeding year the total dry-matter yield in swards sown without a cover crop was increased by infrequent defoliation, but the yield of crude protein was decreased. The highest production of starch equivalent was obtained when a cover crop was used.2. In the absence of a cover crop, the yield of red clover was higher under infrequent defoliation, but the yield of white clover was higher under frequent grazing.3. Frequent grazing, and the use of a cover crop, reduced the ingress of weeds more than infrequent defoliation. Nitrogen applied to the cover crop also reduced the growth of weeds.4. Nitro-chalk increased the total yield of herbage except when under a cover crop; it reduced the growth of red and white clovers, but this was not so marked under frequent grazing.5. Nitro-chalk increased the annual yield of crude protein under frequent grazing, but decreased it in all herbage mixtures under infrequent defoliation; nitrogen had no effect when a cover crop was used. The increase in yield of starch equivalent due to the application of nitrogen and its apparent recovery was greater under frequent grazing than under the other two managements. Under infrequent defoliation, in the absence of a cover crop, the recovery of nitrogen was particularly low.6. The ryegrass mixture and ryegrass-dominant general-purpose mixture made more growth, and suppressed clover and weeds to a greater extent than did the timothy and cocksfoot mixtures. This was modified by management in that ryegrass was particularly aggressive under frequent grazing (management 1) but not under managements 2 and 3.7. In the autumn of the seeding year the yield of total herbage was highest under infrequent defoliation, particularly in the cocksfoot, and general-purpose swards. All undersown mixtures gave lower yields than when no cover crop was used.8. Nitrogen increased the yield of herbage in May and June under frequent grazing, and in the August cut under infrequent defoliation, but in the autumn particularly it was reduced where a cover crop was used.9. The application of nitrogen decreased the protein content in all herbage mixtures when a cover crop was used or when defoliation was infrequent. Under frequent grazing the nitrogen increased the percentage of crude protein in the first two grazings, but decreased it in the September grazing.10. The production from the various mixtures was modified by management: under frequent grazing in May the ryegrass-dominant mixtures were higher yielding than the others, but in July the general-purpose and cocksfoot swards were the most productive. Under infrequent defoliation in August the timothy mixture had the highest yield and cocksfoot the lowest, and under this management cocksfoot and timothy swards had the highest yield in the autumn of the seeding year.