Biological and dry matter yield
In the present study, DM content of crops varied from 25 to 37.4% at the time of ensiling which is well within the range suggested by
McDonald et al., (1991). However,
Beukes (2013) have recommended 30 to 40% whole plant DM for silage preparation. The data revealed that highest biological yield was recorded in B2 while the lowest was recorded in Batch 5 (Table 1). Similarly on DM basis the highest yield was observed for B2 and declined linearly in the subsequent batches. Protein yield and production efficiency followed the same trend. Reduction in biological yield with time of sowing may be due to lowering of temperature at later stage and more availability of water to early sown crops which enhance vegetative growth. Continuous rainfall for 2-3 days just after sowing of J-1006 of B4 and B5 might have affected its biological yield.
Fermentation characteristics
Generally, well-preserved silage contains 4-7% lactic acid, < 3% acetic acid and, <0.1% butyric acid on DM basis. In the present study, the pH and lactic acid were within the range of good quality silage
(McDonald et al., 1991) and butyric acid was not detected in silage (Table 2). Fermentation during ensiling lead to decrease in sugars by 62 to 86%. Fermentation of water-soluble sugars in forages to organic acids (mainly lactic acid) under anaerobic condition is mainly responsible for decrease in pH and level of lactic acid
(Borreani et al., 2018). The lactic acid concentration was comparable in B1, B2 and B5, but higher (P<0.001) than remaining batches. The ammoniacal-N varied from 2.73 to 3.97% of TN among different variants, which is well within the upper limit of 5% of TN on DM basis. The smell of silage was very pleasant.
Effect of time of sowing and processing on the quality and biomass yield
Irrespective of processing, B2 had the lowest (P<0.05) CP content as compared to all other batches which were statistically comparable (Table 3). The cell wall constituents were the highest (P<0.01) in B1 and the lowest values were observed in B5. Irrespective of time of sowing, the DM content in maize was not affected by ensiling, but OM, NDF and hemicellulose content was reduced (P<0.01) in ensiled maize fodder. On the contrary total ash, ADF and cellulose content were increased (P<0.01) in the ensiled maize fodder, confirming the earlier report of
Bakshi et al., (2017).
The IVGP studies revealed that irrespective of processing, the NGP, true OM digestibility and ME availability were the highest (P<0.01) in B5 maize fodder and the lowest (P<0.01) in B3 (Table 4). However, reverse trend (P<0.01) was observed in case of partitioning factor and ammonia concentration. The NDF digestibility varied between 33.2 to 39.09%, confirming the earlier report indicating
in vitro NDF digestibility of whole-plant corn forage ranged from 25 to 60% for 32 corn hybrids grown in four locations
(Allen, 1993). The variation was mainly due to differences in climate, locations and in hybrid genetics. The NGP and true OM digestibility in B5 was comparable with that of B2. Irrespective of time of sowing, the NGP (P<0.05) and ME (P<0.01) availability were depressed in the ensiled maize.
Irrespective of processing, the concentration of total and individual VFAs was the highest (P<0.01) in B5 and lowest (P<0.01) was observed in B1 (Table 5). The best A:P ratio was observed in B4. The total and individual VFAs were improved (P<0.01) after ensiling. The relative proportion of acetate was comparable in B2, B3 and B5, but higher (P<0.01) than B1 and B4. The relative proportion of propionate was comparable in B1 and B4, but higher (P<0.01) than remaining batches. Irrespective of time of sowing, the relative proportion of acetate, propionate and butyrate was not affected by ensiling, however, that of isovalerate was depressed (P<0.01) after ensiling.
Irrespective of processing, the efficiency of rumen fermentation (E) and efficiency of fermented hexose energy to VFA energy (E1) were comparable in B1 and B4, but higher (P<0.01) than the remaining batches (Table 6). The efficiency of fermented hexose to methane (E2) was comparable in B1 and B4, but lower than B5. The efficiency of energy (E, E1 and E2) utilization was not affected by ensiling. However, methane emission increased (P<0.01) after ensiling. The MBP was the highest (P<0.01) in B5 and the lowest (P<0.01) was observed in B1. The MBP was improved (P<0.01) by ensiling.
Irrespective of processing, the predicted DM intake as per cent of BW was the highest (P<0.01) in B5 and the lowest was observed in B1 (Table 7). The predicted nutritional worth as indicated by digestible DM, TDN and NEL were the highest (P<0.01) in B5 and lowest were observed in B1 maize. Irrespective of time of sowing, the predicted DM intake was improved (P<0.01) by ensiling. The data revealed that predicted dry matter intake as percent body weight was 16.7% higher (p<0.01) for silage in comparison to that observed for green fodder. But the nutritive value
i.
e. digestible DM, TDN and NEL were depressed (P<0.01) in ensiled maize fodder.
Effect of number of irrigations and processing on the quality parameters and nutritive value
Irrespective of processing, the maize given two irrigations in comparison to that given single irrigation resulted in higher (P<0.01) DM (31.22 vs 23.88%) and EE (1.78 vs 1.32%) and low NDF (61.58 vs 65.95%), ADF (31.79 vs 36.08%) and cellulose (27.26 vs 32.40%) content. Maize silage had low hemicelluloses and lignin content (28.29 vs 31.37% and 4.67 vs 5.17%) in comparison to that observed in green fodder, irrespective of number of irrigations.
Number of irrigation and processing (green fodder vs silage) showed no effect on NGP, digestibility of nutrients, PF and ME. The total VFAs (5.20 vs 3.98 mM/DL), acetate (3.10 vs 2.29 mM/DL), propionate (1.33 vs 1.08 mM/DL) and butyrate (0.51 vs 0.41mM/DL) were higher (P<0.05) in maize provided two irrigations in comparison to that given single irrigation.
The predicted DMI as percent of body weight was 7% higher (P<0.01) in maize fodder given two irrigations in comparison to that given single irrigation (1.95 vs 1.82% BW). The nutritive value of maize fodder
i.
e. digestible DM was higher (P<0.01) in maize given two irrigations instead of one (94.14 vs 60.80%), resulting in higher (P<0.01) TDN (65.59 vs 62.59%) and NEL value (1.49 vs 1.41Mcal/kg DM). However, processing, irrespective of number of irrigations showed no effect on these parameters. Maize fodder given two irrigations gave higher (P<0.01) MBP in comparison to that given single irrigation (132.23 vs 101.16 g/day). Similarly, ensiled maize had higher (P<0.05) MBP in comparison to green fodder (129.45 vs 103.94 g/day). It was concluded that B5 maize fodder with the lowest yield given two irrigations had the best nutritive value.