Protein supplementation of cows grazing limited amounts of paspalum (Paspalum dilatatum Poir.)-dominant irrigated pasture in mid-lactation

2000 ◽  
Vol 40 (7) ◽  
pp. 923 ◽  
Author(s):  
W. J. Wales ◽  
D. W. Dellow ◽  
P. T. Doyle

Two experiments were undertaken in summer to investigate production responses by dairy cows offered paspalum (Paspalum dilatatum Poir.)-dominant irrigated pasture to the inclusion of protein supplements with different rumen degradable protein characteristics in cereal grain-based concentrates. In experiment 1, cows in mid lactation were offered limited amounts of herbage, at an allowance of 28 kg DM/cow. day together with 8.0 kg DM/cow. day of a pelleted supplement containing: (i) mainly barley and wheat; (ii) barley, wheat and canola meal; or (iii) barley, wheat and cottonseed meal for 35 days. The 3 supplements were formulated to have similar in vitro DM digestibilities. In experiment 2 aspects of rumen function were measured in 9 rumen fistulated lactating cows, individually fed indoors on paspalum-dominant herbage harvested daily with a finger bar mower. Cows were offered the same amount of supplements for 28 days. Pasture intakes were similar to those of the grazing cows in experiment 1. In experiment 1, there were no effects (P>0.05) of dietary treatment on herbage intake (10.2 kg DM/cow. day) or selection of nutrients from herbage. The concentration of crude protein in the total diet consumed was lower (P<0.05) for the barley + wheat treatment (137 g/kg DM), compared with the barley + wheat + canola meal and barley + wheat + cottonseed meal treatments, which were 179 and 183 g/kg DM, respectively. In vitro DM digestibility of the feed consumed by cows was similar across the treatments, and all diets contained greater than 400 g neutral detergent fibre/kg DM, indicating there were no limitations due to dietary fibre. There were no significant effects (P>0.05) of dietary treatments on milk production (21.8 kg/cow. day), milk fat concentration (34.1 g/kg) or milk protein concentration (29.8 g/kg). Urea-N was higher (P<0.01) in the milk of cows fed the barley + wheat + canola meal and the barley + wheat + cottonseed meal treatments compared with the barley + wheat treatment. In experiment 2, rumen fluid pH was higher in cows consuming barley + wheat pellets than in cows consuming barley + wheat + canola meal on most sampling occasions. Rumen ammonia-N concentration was lowest in the barley + wheat treatment and highest in the barley + wheat + canola meal treatment. When cows grazing paspalum-dominant irrigated pasture were supplemented with 8 kg DM of a cereal-based supplement, metabolisable protein was calculated to be present in sufficient quantities to support at least 22 kg milk/cow. day and, hence, was not limiting milk production. It is concluded that protein supplements offered to cows in mid-lactation, grazing irrigated pastures in summer, are unlikely to give a milk production response beyond that achieved with cereal grain.

1996 ◽  
Vol 36 (7) ◽  
pp. 763 ◽  
Author(s):  
M Reeves ◽  
WJ Fulkerson ◽  
RC Kellaway

Three studies were conducted to examine the production response of Friesian cows grazing well-managed lukuyu (Pennisetum clandestinum) pasture to supplementation with a cereal grain concentrate, with and without the inclusion of formaldehyde-treated protein meal. Mean (¦ s.e.) levels of nutrients in the pasture (g/kg DM) on offer were: 205 ¦ 3 crude protein; 683 ¦ 7 in vitro organic matter digestibility; 239 ¦ 2 acid detergent fibre; 615 ¦ 8 neutral detergent fibre and 4.47 ¦ 0.16, 2.51 ¦ 0.06, 31.96 ¦ 0.98, 0.39 ¦ 0.03 and 3.18 ¦ 0.09 of calcium, phosphorus, potassium, sodium and magnesium, respectively. Study 1 was a 3-farmlet study conducted over 45 days (March-April 1993) involving cows 5-6 months into lactation, which compared 3 levels of concentrate feeding at 0 (R0), 3 (R3) or 6 (R6) kg crushed barley/cow.day. Study 2 was an 18-day extension of study 1 with animals in the seventh month of lactation. The concentrate fed was 72% barley and 24% formaldehyde-treated sunflower meal. Pasture intake of individual cows was determined using an alkane technique. Mean milk yields (L/cow. day) in study 1 were 14.2, 18.3 and 18.0, and in study 2 were 12.5, 18.5 and 17.4 for treatments R0, R3 and R6, respectively. Milk fat (3.77 v. 3.26%), but not milk protein, content of the Ro cows was significantly higher than R6 cows in study 1 only. In study 2, the apparent whole-diet digestibility remained constant as concentrate level rose, indicating a negative effect of concentrate fed on forage digestibility in the absence of buffers. Study 3 was a 3 x 4 factorial design plus a 'control' group (0.5 kg barley/cow.day used as a carrier for minerals) to examine the milk production response to 3 levels of concentrate feeding (3, 6 and 9 kg/cow.day) with 4 levels of formaldehyde-treated canola meal (FTCM; 0, 20, 40 and 60% of concentrate). Rations were iso-energetic within levels of concentrates fed. The control group had significantly lower milk production (17.2 L/cow.day), as well as milk protein (2.90%), plasma urea (PU) (5.90 mmol/L) and P-hydroxybutyrate (G-OHB) (0.525 mmo1L) than other treatment groups. The mean milk production response of 0.6 L milk/kg concentrate fed in study 3 at the 3 kg/day level of feeding was lower than observed in studies 1 and 2 (1.4 and 2.0 L/kg concentrate, respectively). The level of metabolisable energy in the concentrate in study 3 had a significant influence on milk production, milk fat and milk protein levels. Plasma glucose and G-OHB levels significantly increased with the incorporation of FTCM into the concentrate. Nonesterified fatty acid levels dropped significantly below levels of other treatments at the lowest level of inclusion of FTCM. PU levels generally increased in response to increasing metabolisable energy and inclusion of FTCM in the concentrate, with an interaction between them. Milk urea (MU) levels (mmol/L) showed a significant linear (P<0.001; r2 = 0.44) relationship to PU levels (mmol/L) as follows: MU = 0.167 + 0.272PU.


2005 ◽  
Vol 45 (12) ◽  
pp. 1507 ◽  
Author(s):  
C. R. Stockdale

The experiment was an investigation into the interaction between body condition at calving and the provision of additional dietary energy or protein to a total mixed ration (TMR) in late gestation on milk production and indices of reproductive performance. Seventy-two Holstein–Friesian multiparous cows (12 per treatment) were fed to achieve target body condition scores (BCS) of either 4 (3.5–4.5) or 6 (5.5–6.5) units by 1 month before they calved (July). They were individually fed 1 of 3 diets during the last 26 (s.d. ± 7.4) days before calving date (mean of 19 August; s.d. ± 9.7). The 3 diets were (1) a TMR containing maize silage, barley grain, canola meal and hay, fed at 1.5% of liveweight (control diet), (2) the TMR plus 3.5 kg DM of wheat-based pellets (energy diet), and (3) the TMR plus 3.1 kg DM of soyabean meal (protein diet). Cows grazed highly digestible pasture after calving at pasture allowances of about 35 kg DM/cow.day, and were supplemented with 6 kg DM of cereal grain-based pellets per day. Cows were fed this diet for an average of about 10 weeks, from calving until the start of mating at the end of October. The provision of additional dietary energy and protein before calving did not affect post-partum production, and there were no interactions with body condition. On average, the BCS 6 cows were 111 kg heavier (P<0.05), and were 1.8 units of body condition higher (P<0.05), than the BCS 4 cows. The thin cows maintained body condition during the month before parturition while the fat cows lost condition. The cows offered additional protein improved their body condition (+0.07 units) during this time, while the cows in the other 2 dietary treatments lost condition (–0.10 units). Average daily rumen fluid pH was lowest in the cows fed the additional energy. Blood urea and rumen fluid ammonia concentrations were increased markedly by feeding the protein diet. In comparison with cows offered the control and energy diets, the cows offered additional protein had the highest (P<0.05) urine pH levels (6.24 v. 5.64 and 5.59 for the protein, control and energy diets, respectively), the lowest (P<0.05) blood serum concentrations of calcium at calving (1.74 v. 2.06 and 1.99 mmol/L for the protein, control and energy diets, respectively), and tended to have more milk fever and retained foetal membranes. Regression analysis indicated that the response to improving BCS at calving was 1.1 kg milk per additional BCS at calving (P<0.05), and the fatter cows produced milk with a higher (P<0.05) milk fat concentration (3.46 v. 3.07%) than the thinner cows. There was no effect (P>0.05) of treatment on days to first ovulation or in-calf rates although only about 80% of cows conceived during the 12-week mating period.


1999 ◽  
Vol 39 (6) ◽  
pp. 645 ◽  
Author(s):  
W. J. Wales ◽  
P. T. Doyle ◽  
D. W. Dellow

Summary The nylon bag technique was used to estimate the degradability of the dry matter (DM) and crude protein (CP) of herbage samples and supplementary feeds from recent grazing experiments with dairy cows conducted in Victoria. The cumulative disappearance data for CP were used to calculate the effective rumen degradability of CP (ERDP, g/kg DM) for these feeds at rumen outflow rates of 0.02, 0.05 or 0.08/h. Crude protein was more extensively degraded than DM in all herbage samples collected before grazing, or in those samples taken to represent the herbage consumed by grazing cows. The ERDP of spring pastures (excluding the dead material and postgrazed samples) was generally in the range 103–197 g/kg DM, at an outflow rate of 0.02/h and in the range 74–142 g/kg DM, at an outflow rate of 0.08/h. For summer pastures, the ERDP was generally in the range 80–128 g/kg DM, at an outflow rate of 0.02/h and in the range 58–108 g/kg DM, at an outflow rate of 0.08/h. For autumn pastures, ERDP ranged from 108 to 170 g/kg DM, at an outflow rate of 0.02/h and from 84 to 140 g/kg DM, at an outflow rate of 0.08/h. There were only 2 herbage samples collected during the winter, which had ERDP of 237 and 249 g/kg DM, at an outflow rate of 0.02/h and 213 and 222 g/kg DM, at an outflow rate of 0.08/h. Values for ERDP tended to be higher for these winter samples compared with spring samples. In contrast, autumn samples tended to have lower ERDP than spring samples. It is shown that metabolisable protein is unlikely to limit milk production of cows consuming 17 kg herbage DM/cow. day and producing up to 30 L milk/day, when milk production is determined from metabolisable energy supply. The excesses in metabolisable protein ranged from 0.48 to 1.21 kg/cow. day from a subset of spring herbage samples cut to represent that selected by cows and from 0.14 to 0.23 kg/cow. day from summer herbage samples. The degradability characteristics of the herbage samples were similar to some estimates for temperate herbages in the United Kingdom and from limited data from Australia and should form a useful basis on which to assess whether additional metabolisable protein is required as supplements for dairy cows grazing pastures in Victoria. There was a positive (P<0.01) relationship between CP content and ERDP (R2 = 0.93), across herbage samples indicating it could be possible to estimate ERDP for herbage samples that have been assessed for CP content. There was also a significant (P<0.01) positive relationship between the effective degradability of DM of herbage and ERDP (R2 = 0.77). The relationships between in vitro dry matter digestibility or neutral detergent fibre and ERDP were also significant (P<0.01), but accounted for even less of the variability. The ERDP in cereal grain-based supplements ranged from 87 to 111 g/kg DM, at a outflow rate from the rumen of 0.02/h, compared with 70–92 g/kg DM, at an outflow rate of 0.08/h. The compounded supplements containing varying levels of cereal grain, lupins and cottonseed meal, had effective degradabilities of CP that generally declined as the content of lupins decreased and the content of cottonseed meal increased. However, ERDP increased to 152 g/kg DM because of the increasing CP content with increasing cottonseed meal. These results are compared with previously published estimates of effective degradability of CP for supplementary feeds.


2001 ◽  
Vol 41 (1) ◽  
pp. 1 ◽  
Author(s):  
G. P. Walker ◽  
C. R. Stockdale ◽  
W. J. Wales ◽  
P. T. Doyle ◽  
D. W. Dellow

Two grazing experiments tested the hypothesis that a cereal grain-based supplement, fed to cows that are in mid–late lactation and grazing low metabolisable energy and high neutral detergent fibre content paspalum (Paspalum dilatatum Poir.)-type pastures, will increase milk yield, but that this response will diminish with successive increments of supplement. A further objective of this research was to investigate some of the factors, such as altered rumen fermentation pattern, that might vary the point at which diminishing returns start to occur. Cows grazed irrigated perennial pasture at an allowance of either 25 (experiment 1) or 31 (experiment 3) kg of dry matter (DM) per cow per day in late summer–early autumn (mid–late lactation) and were supplemented with cereal grain-based concentrates up to 11 and 7 kg DM/cow.day in experiments 1 and 3, respectively. In experiment 1, there were 3 replicates of 6 treatments (3 cows in each treatment group) that involved the feeding of either 0, 3, 5, 7, 9 or 11 kg DM/cow.day of supplement for 50 days. Experiment 3 was conducted over 35 days. There were 2 replicates of 4 treatments (4 cows per treatment group) that involved the feeding of either 0, 3, 5 or 7 kg DM/cow.day of supplement. A further experiment (experiment 2), associated with experiment 1, examined the effects of offering cereal grain-based concentrates up to 7 kg DM/cow.day to dairy cows consuming 10 kg DM/day of herbage with a high paspalum content on aspects of rumen fermentation. Incremental responses of 40 g/kg fat-corrected milk (FCM) to increasing concentrate intake diminished with increasing concentrate intake, with the level of supplementation at which diminishing returns occurred dependent on herbage allowance and, therefore, herbage intake. At a supplement intake of 3 kg DM/cow.day, the response in FCM was 1.1 kg/kg concentrate DM in both grazing experiments. There were no further increases in milk production with additional increments of concentrates in experiment 3 where the pasture allowance was highest. In experiment 1, where concentrates were offered to a level of 11 kg DM/cow.day, and the pasture allowance was lower, diminishing returns were not as pronounced as in experiment 3 until the highest levels of concentrate intake. Substitution of supplement for herbage was a major factor in causing the diminishing returns in both experiments, but especially in experiment 3, where pasture intakes were higher. Milk fat content was significantly (P<0.05) reduced (41.8 v. 32.5 g/kg) when concentrate intake increased from 9 to 10.4 kg supplement DM/cow.day in experiment 1. It was hypothesised that this reduction in milk fat content was probably due to the effects of subclinical rumen lactic acidosis. This hypothesis was supported by the trend to lower rumen pH for longer periods as supplement intake increased as well as a more variable milk yield at the highest level of supplement intake. We conclude that responses of FCM of 1.1 kg/kg DM cereal grain-based concentrates can be achieved when they are fed twice daily up to 3 kg DM/day to dairy cows grazing restricted amounts of paspalum-type pasture in autumn. Beyond 3 kg DM/day, marginal responses diminished with increasing concentrate intake, with the level of supplementation at which diminishing returns occurred being dependent on herbage allowance and, therefore, intake.


2003 ◽  
Vol 43 (5) ◽  
pp. 467 ◽  
Author(s):  
W. J. Wales ◽  
P. T. Doyle

The marginal milk-production response to cereal grain supplementation of dairy cows grazing irrigated subterranean clover (Trifolium subterraneum L.) pasture in spring was investigated. We also determined whether the addition of a perennial ryegrass (Lolium perenne L.) straw supplement would improve that response. There were 8�replicated treatments in a factorial design with 2 amounts of cereal grain pellet [0 and 5.0 kg dry matter (DM)/cow.day] and 4 amounts of straw (0, 0.5, 1.0 and 2.0 kg DM/cow.day), 48 cows in total. Cows in all treatments grazed subterranean clover at an allowance (measured to ground level) of 19 kg DM/day. The barley and wheat pellet and straw had a neutral detergent fibre (NDF) concentration of 164 g/kg DM and 704 g/kg DM, respectively. Cows from all treatments consumed pasture with an in vitro DM digestibility of 743�g/kg DM and NDF concentration of 313 g/kg DM, compared with the pregrazed pasture on offer of 707 and 360, respectively. Pasture DM intake was not affected (P>0.05) by supplementation with either grain or straw, and averaged 12.7�kg�DM/cow.day. Cows supplemented with grain achieved a marginal milk-production response of 1.0�kg�fat-corrected milk (FCM)/kg DM grain. However, with increasing amounts of straw, responses of 0.0, 0.9 and 0.5 kg FCM/kg DM grain were observed. Fat-corrected milk yields were not different (P>0.05) between straw treatments and averaged 25.8 kg FCM/cow.day. Grain feeding significantly (P<0.05) reduced milk fat concentration and increased (P<0.05) milk protein concentration, although offering increasing amounts of straw had no significant (P>0.05) effect on either milk fat or milk protein concentration. Average ruminal fluid pH was significantly (P<0.05) lower when cows consumed cereal grain pellets than with those treatments without cereal grain (5.82 v. 6.09). There were no differences (P>0.05) in ruminal fluid pH among cows that consumed different amounts of straw. When cows were managed to limit intake of subterranean clover by restricting pasture allowance, supplementation with cereal grain resulted in acceptable marginal milk-production responses of 1.0 kg FCM/kg DM cereal grain. Under these circumstances, providing additional NDF as straw did not improve the milk-production response to cereal grain, with NDF ranging from 290 to 337 g/kg DM when 0–1.7 kg DM straw was consumed.


2001 ◽  
Vol 41 (4) ◽  
pp. 465 ◽  
Author(s):  
W. J. Wales ◽  
Y. J. Williams ◽  
P. T. Doyle

An experiment was undertaken to establish the marginal milk production response from cereal grain supplementation by dairy cows grazing irrigated perennial pastures in spring and whether the addition of a hay supplement would improve that response. Cows were offered perennial ryegrass (Lolium perenne L.)–white clover (Trifolium repensL.) pasture at allowances (measured to ground level) of 20 or 40 kg dry matter (DM)/cow.day. Additional cows offered the low allowance were also offered supplements of pasture hay as a cube or pellet (2.5 kg DM/day), cereal grain as a pellet (5.0 kg DM/day) or cereal grain plus pasture hay (7.5 kg DM/day) as a pellet (1.75:1 DM basis) or cube (1.97:1 DM basis). The 7 treatments were replicated 3 times, and 63 cows were used (3 cows/treatment). The in vitro DM digestibility, crude protein and neutral detergent fibre (NDF) concentration of the barley and perennial pasture hay were 863 and 563 g/kg DM, 131 and 92 g/kg DM, and 182 and 666 g/kg DM, respectively. Cows from all treatments consumed herbage with an in vitro DM digestibility of 833 g/kg DM, crude protein content of 214 g/kg DM and NDF concentration of 457 g/kg DM compared with the pregrazed herbage on offer of 771, 174 and 527 g/kg DM, respectively. The mean pregrazing herbage mass of 4.13 t DM/ha consisted of perennial ryegrass (507 g/kg DM), white clover (188 g/kg DM), weeds (194 g/kg DM) and dead material (111 g/kg DM). Without supplements, cows consumed 11.2 kg DM/day at the low pasture allowance and 15.6 kg DM/day at the high allowance. Herbage intake did not decline to a large degree when barley was included in the diet, where a substitution rate of 0.2 kg reduction in pasture DM/kg DM cereal grain supplement was measured. The NDF concentration of the diet consumed was lowest (P< 0.05) for the grain pellet treatment (370 g NDF/kg DM) and highest (P&lt;0.05) for the fibre pellet (493 g NDF/kg DM) and the fibre cube (507 g NDF/kg DM) treatments. Fat-corrected milk yield increased (P<0.05)) from 20.1 to 24.5 kg/cow.day when cows consumed 4.5 kg DM cereal grain/day with a marginal milk response of 1.0 kg 4% fat-corrected milk/kg DM concentrate supplement. Supplementation with grain or hay had no significant effect (P>0.05) on milk fat, protein or lactose concentrations. The cows offered the high allowance spent more (P<0.05) time grazing than those offered the low allowance, but there were no significant differences in rumination time. Cows spent more time ruminating when consuming the grain &plus; fibre cube compared with the other supplement treatments, which were lower (P<0.05) and similar. Cows offered pasture at the low allowance ruminated the least. The rumen pH was not different between treatments and averaged 5.9. The ratio of acetate plus butyrate: propionate was not different between treatments and averaged 4.3. This study has shown that feeding cereal grain to cows grazing pastures high in perennial ryegrass resulted in acceptable marginal milk responses of 1 kg milk/kg DM of cereal grain in spring because of sufficient NDF in the diet. As there was adequate NDF in the diet, further supplements with pasture hay as cubes or pellets had no effect on marginal milk responses .


1995 ◽  
Vol 75 (4) ◽  
pp. 625-629 ◽  
Author(s):  
R. R. Corbett ◽  
L. A. Goonewardene ◽  
E. K. Okine

The effect of substituting peas for soybean and canola meals as a protein source in a high-producing dairy herd was studied in 66 Holstein cows, divided into two groups based on stage of lactation, parity, level of milk production and days in milk. Two 18.5% crude protein grain concentrate diets were formulated based on the nutrient analyses of the forages available. The control grain mix contained standard protein sources, principally soybean and canola meal (SBM\CM) while the test grain mix was formulated to contain approximately 25% field peas as the major source of protein. Both grain rations were formulated to the same nutrient specifications and balanced for undegradable protein. The duration of the trial was 6 mo during which grain feeding levels were adjusted monthly based on milk yield. For cows in early lactation, 4% fat-corrected milk yield was higher (P < 0.05) for cows fed pea based concentrates (31.3 kg d−1) than for cows fed SBM\CM supplement (29.7 kg d−1). Fat-corrected milk yield was not affected by source of protein in mid- and late-lactation cows. Fat-corrected milk production was not different (P > 0.05) for cows fed SBM\CM compared with cows fed the pea supplement when cows across all stages of lactation were included in the analyses. Milk fat percent was significantly higher (P < 0.05) for early- and mid-lactation cows fed the pea supplement. The results suggest that peas can be substituted for SBM\CM as a protein source for high-producing dairy cows. Key words: Dairy cow, pea, soybean and canola meal supplement, undegradable protein, milk production


2017 ◽  
Vol 84 (3) ◽  
pp. 240-247 ◽  
Author(s):  
Ruairi P McDonnell ◽  
Martin vH Staines

This research paper describes the effect of partially replacing wheat with maize grain and canola meal on milk production and body condition changes in early lactation Holstein-Friesian dairy cows consuming a grass silage-based diet over an 83-d period. Two groups of 39 cows were stratified for age, parity, historical milk yield and days in milk (DIM), and offered one of two treatment diets. The first treatment (CON) reflected a typical diet used by Western Australian dairy producers in summer and comprised (kg DM/cow per d); 8 kg of annual ryegrass silage, 6 kg of crushed wheat (provided once daily in a mixed ration), 3·6 kg of crushed lupins (provided in the milking parlour in two daily portions) and ad libitum lucerne haylage. The second treatment diet (COMP) was identical except the 6 kg of crushed wheat was replaced by 6 kg of a more complex concentrate mix (27% crushed wheat, 34% maize grain and 37% canola meal). Lucerne haylage was provided independently in the paddock to all cows, and no pasture was available throughout the experiment. The COMP group had a greater mean overall daily intake (22·5vs20·4 kg DM/cow) and a higher energy corrected milk (ECM) yield (29·2vs27·1 kg/cow;P= 0·047) than the CON cows. The difference in overall intake was caused by a higher daily intake of lucerne haylage in COMP cows (4·5vs2·3 kg DM/cow). The CON group had a higher concentration of milk fat (42·1vs39·3 g/kg;P= 0·029) than COMP cows. Milk protein yield was greater in COMP cows (P< 0·021); however, milk fat yield was unaffected by treatment. It is concluded that partially replacing wheat with canola meal and maize grain in a grass silage-based diet increases voluntary DMI of conserved forage and consequently yields of ECM and milk protein.


Author(s):  
M.M. Abubakar ◽  
P. Rowlinson

The antibiotic Actaplanin is a complex of glycopeptide compounds produced by Actinoplanes missourrensis. When included in feed as a performance enhancer it has been shown to increase milk production of dairy cows (McGuffey et al. 1983). Actaplanin is associated with reduced proportions of acetate and increased proportions of propionate in rumen fluid and a depression in milk fat proportion may result (Clapperton et al. 1987). The aim of the trial reported here was to monitor the effects of feeding 960 mg Actaplanin/head/d to dairy cows throughout two successive lactations.


1998 ◽  
Vol 22 ◽  
pp. 202-204
Author(s):  
C. D. Wood ◽  
N. S. Prathalingam ◽  
A. M. Murray ◽  
R. W. Matthewman

A major focus for improving the diets in many less developed countries (LDCS) is the provision of rumen fermentable nitrogen (N) using protein supplements to complement N-deficient foods. However, in vitro digestibility methods usually use N-rich environments for the degradation of single foods. This conventional approach may give data which do not reflect the nutritive value of the N-deficient diets often on offer in LDCS, neither is it appropriate for using in vitro gas production to study protein supplementation. Our earlier study indicated that, by using a N-free medium, the gas production technique responded to added ammonium sulphate and urea. The ADAS standardized methodology, which used 10 ml of inoculum instead of the 5 ml used in the earlier study, was found not to be very responsive to N supplementation. The ADAS methodology was therefore investigated in order to develop a modified protocol for fermenting foods in an N-limited environment. The study involved using inocula diluted to different extents in N-free medium for fermenting N-deficient substrates in N-free and N-rich media. The modified protocol was then used for investigating the interactions between N-rich and N-deficient foods from north-west India.


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