Abstract: This study was conducted to compare productive potential and nutritional worth of maize (Zea mays), sorghum (Sorghum bicolor) and millet (Pennisetum americanum) fodders. These fodders were grown in experimental plots (1.8x6 m of each) according to Completely Randomized Design. Each fodder was manually harvested at three physiological stages i.e., pre heading (CS1), heading (CS2) and milk stage (CS3). The results showed that green fodder, Dry Matter (DM), Crude Protein (CP) and Total Digestible Nutrient (TDN) yields (ton ha-1) increased with the advancement of age of all fodders. The maximum yield of three fodders was noticed at milk growth stage. Higher green fodder and DM yield was observed in millet than those of maize and sorghum fodders. Whereas, higher CP yield was noticed in maize than those in sorghum and millet fodders. However, TDN yield was similar in both maize and millet fodders. The DM, Neutral Detergent Fibre (NDF), Acid Detergent Fibre (ADF), Acid Detergent Lignin (ADL) and Water Soluble Carbohydrate (WSC) contents increased (p<0.05) in all three fodders with advancing age. However, CP, TDN and Metabolizable Energy (ME) contents decreased (p<0.05) in all fodders with the advancement of their growth. In situ DM, Organic Matter (OM) and NDF digestibilities of three fodders decreased (p<0.05) with the advancement of age both at 24 and 48 h of ruminal incubation. The DM, OM and NDF digestibilities of maize, sorghum and millet fodders decreased with advancing age by 11.10, 18.48 and 14.08%; 10.24, 11.25 and 12.18% and 12.59, 18.36 and 23.69%, respectively at 48 h of ruminal incubation. Based upon biomass and nutrient yields, the milk growth stage was the best physiological stage irrespective of the type of fodders.
INTRODUCTION
Production of good quality fodder is of a great importance for the economical ruminant production. Both quantity and quality of fodder are influenced due to soil variation (Yar and Waheed, 1991), plant species (Kaiser and Piltz, 2002), climatic conditions (Siefers et al., 1997), water supply (Rashid and Salim, 1989), stage of growth (Kim et al., 2001), frequency of cutting (Bilal, 1998) and agronomic practices (Rehman and Khan, 2003).
Stage of growth is one of the most important factors influencing nutritional quality of fodder (Fariani et al., 1994). Sullivan (1973) reported that the nutritive value of a fodder depended upon the morphological and physiological changes. As the fodder matures, the cytoplasmic portion of the cell reduces and the quantity of protein, lipids, soluble carbohydrates and soluble minerals decrease. The protein and lipid contents of forage are negatively correlated to the maturity of fodder (Cleale and Bull, 1986). However, Dry Matter (DM) content increases with advancing the age of fodder (Azim et al., 1989). Similarly, the cell wall contents increase and cell wall become lignified with maturity of fodder (Kim et al., 2001). However, the quality of fodder is very high at an early stage of growth, but yield of DM per unit area is very low (Fariani et al., 1994). Therefore, in order to get more nutrients per unit area, the optimum time, keeping in view its nutritive value and DM yield, of harvest must be considered. Firdous and Gilani (1999) suggested that maize fodder should be cut preferably between 8th to 9th week after sowing to obtain maximum nutritious and digestible feed for livestock. Firdous and Gilani (2001) suggested that optimum harvesting for sorghum was at flowering stage. Similarly, Grewal et al. (2003) suggested that millet fodder might be harvested at pre-boot stage of maturity. Utley et al. (1995) compared the Crude Protein (CP) yield of spring crop and late summer crop of pearl millet with maize fodder. Crude protein yield for maize fodder was 30% greater than that of first crop millet and twice the amount produced by the second crop millet.
Variation in the contents of structural carbohydrate occurred with seasonal changes as well as growth stage (Singh, 1976). Digestibility of cell contents and cell wall contents decreased with maturity of maize and sorghum fodder (Havilah et al., 1995). In contrast to the above findings, DeBoever et al. (1993) reported that maturity stages (from milk dough to hard dough stages) had no clear effect on Organic Matter (OM) digestibility when 14 maize fodder samples were investigated.
Little information is available on the yield/ha and nutrient availability of maize (Zea mays), sorghum (Sorghum bicolor) and millet (Pennisetum americanum) in Pakistani environment. An attempt is, therefore, made to determine comparative production efficiency (yield ha-1), nutritive value of local maize, sorghum and millet fodders at their different physiological stages.
MATERIALS AND METHODS
Fodders
Maize, sorghum and millet fodders were grown in the experimental field of
Animal Nutrition Institute, National Agricultural Research Center (NARC) Islamabad,
Pakistan in the year, 2004. Soil type at the site was well drained calcareous
silt loam. Akbar, Hegari and NARC-5 varieties of maize, sorghum and millet,
respectively, were grown for this study. The experiment was conducted according
to Completely Randomized Design. Each fodder plot size was 1.8x6 m. The meteorological
data were recorded by Agro-meteorological Department at NARC, Islamabad, Pakistan
during the experimental period (Table 1).
Seed Germination Test
To determine the percentage of viable seed, 100 seeds of each experimental
fodder were placed on moist filter paper in petri dishes and kept at room temperature
following the standard techniques as described by Myers (1952).
| Table 1: | Meteorological data during Kharif season (2004) |
| Altitude 518 m; Latitude 33° 42'; Longitude 73° 08'. *: Source: Agro Meteorological Department, National Agricultural Research Center, Islamabad, Pakistan (Annual Report, 1998/1999) | |
The seed germination rate of each experimental fodder was found to be in the range of 95-97%. The results were very close to the recommendation of fodder section at NARC, Islamabad. Before applying the seeds to field, foreign materials (weed, other seed, stone and soil) were removed from the seed of each fodder.
Cultivation of Fodders
Seed of maize, sorghum and millet was sown at rates of 100, 75 and 15 kg
ha-1, respectively (Ahmad et al., 2003) using hand drill.
The rows were 30 cm apart (Hussain et al., 1995). The field was fertilized
uniformly at the rate of 60 kg each of N and P ha-1 in such a way
that full dose of phosphorus (diammonium phosphate) and half of nitrogen (urea)
was applied at the time of sowing (Ahmad et al., 2003). The remaining
half dose of nitrogen was applied after one month of sowing. During the experimental
period, the field was irrigated thrice from dam water with an interval of 15-21
days. One hoeing was done before the first irrigation.
Harvesting of Fodder
The fodders were manually harvested at three stages of maturity. Maize,
sorghum and millet fodders were harvested at pre-heading (CS1), heading
(CS2) and milk stage (CS3). Green fodder yield ha-1
was recorded at all stages of maturity. The DM, CP and Total Digestible Nutrient
(TDN) yield ha-1 were calculated on the basis of chemical analysis.
The samples of each fodder cut at three vegetative stages of maturity were chopped in a locally manufactured chopper. Samples were dried at 55°C and ground to particle size of 2 mm through a Wiley mill. These samples were analyzed for DM, CP using method described by AOAC (1990), Neutral Detergent Fibre (NDF), Acid Detergent Fibre (ADF), Acid Detergent Lignin (ADL) by the methods of Goering and Van Soest (1970) and Water Soluble Carbohydrates (WSC) by the procedure of Dubois et al. (1956) and modified by Johnson et al. (1966). Total digestible nutrient and Metabolizable Energy (ME) contents of each fodder samples cut at three vegetative stages were calculated by the equations of Wardeh (1981) and Moe and Tyrrell (1976), respectively.
In situ Digestibility
Four grams of dried samples in duplicate were weighed into dacron polyester
bags having average pore size of 50 μm with dimension of 7"x4" (Orskov,
1980). These bags were closed and tied with nylon fishing line before placing
in the dorsal sac of the rumen of two sheep fitted with permanent ruminal canola
(40 mm diameter). The sheep were fed the same fodder as were being incubated
in their rumens. This was done to avoid the effects of diet on the ruminal fermentation
of the feedstuffs (Clark and David, 1990). All bags, including empty bags to
act as blank, were simultaneously incubated in the rumen for 24 and 48 h after
removal from the rumen, bags were washed in running tap water until the rinse
was clear. The bags were then dried in a hot air oven at 60°C for 48 h and
then weighed back and the residues were stored for subsequent analyses. The
in situ digestibility for DM, OM and NDF at 24 and 48 h of ruminal incubation
was calculated according to the procedure described by Sarwar et al.
(1995).
Statistical Analysis
Data of chemical composition and digestibility of fodders at three vegetative
stages were statistically analyzed by using Completely Randomized Design. Duncan’s
Multiple Range tests were used to compare the treatment means (Steel and Torrie,
1980).
RESULTS AND DISCUSSION
Green Fodder Yield
The green fodder yields of millet (19.57 ton ha-1) and sorghum
(19.77 ton ha-1) were higher (p<0.05) than that of maize (17.89
ton ha-1) harvested at pre heading stage (Table 2).
However, no difference (p>0.05) in yield was noticed between millet and sorghum
fodders. The green fodder yield of millet (36.49 ton ha-1) was higher
(p<0.05) than those of sorghum (32.45 ton ha-1) and maize (31.37
ton ha-1) harvested at heading stage. Similarly, the green fodder
yield of millet (48.39 ton ha-1) was higher (p<0.05) than those
of sorghum (46.38 ton ha-1) and maize (46.06 ton ha-1)
harvested at milk stage. However, no difference (p>0.05) in yield was observed
between sorghum and maize fodders.
The results of the present study were consistent with those of Paroda (1976), Bhatti (1996) and Hinjra (1996) who reported a higher green fodder yield of millet than those of sorghum and maize fodders. They explained that higher yield of millet was due to its high leaf-to-stem ratio. Yar and Waheed (1991) reported that the range of green fodder yield of six millet fodder varieties harvested at full mature stage ranged from 36.73-50.47 ton ha-1. These yield values are comparable to the green fodder yield of millet fodder (48.39 ton ha-1) of the present study.
Dry Matter Yield
The DM yield of millet (8.67 and 16.84 ton ha-1) was higher (p<0.05)
than those of maize (7.33 and 15.38 ton ha-1) and sorghum (7.30 and
15.80 ton ha-1) fodders harvested at heading and milk stages, respectively
(Table 3). However, the DM yield of millet (3.06 ton ha-1)
was lower (p<0.05) than those of sorghum (3.58 ton ha-1) and maize
(3.47 ton ha-1) fodders harvested at pre heading stage. The results
of this study were concordant to annual report (1998-99), which stated that
the DM yield of millet fodder was higher than that of maize fodder. Weiss and
Wyatt (2000) reported 15.90 ton ha-1 DM yield of maize fodder at
mature stage, which was comparable to the present study (15.38 ton ha-1).
Crude Protein Yield
The CP yield was higher (p<0.05) in maize (0.57, 0.86 and 1.53 ton ha-1)
than those of sorghum (0.36, 0.69 and 1.16 ton ha-1) and millet (0.29,
0.70 and 1.17 ton ha-1) fodders when harvested at pre heading, heading
and milk stages, respectively (Table 4). Similar findings
were reported by Utley et al. (1995) who noticed that CP yield of maize
fodder was 30% higher than that of millet fodder at mature stage.
| Table 2: | The comparative green fodder yield (ton ha-1) of maize, sorghum and millet fodders at three vegetative stages of growth |
| Mean in the same column bearing different superscripts were significantly, (p<0.05) different, *: CS1, CS2 and CS3 stand for pre heading, heading and milk stages, respectively | |
| Table 3: | The Comparative dry matter yield (ton ha-1) of maize, sorghum and millet fodders at three vegetative stages of growth |
| Mean in the same column bearing different superscripts were significantly (p<0.05) different, *: CS1, CS2 and CS3 stand for pre heading, heading and milk stages, respectively | |
| Table 4: | The Comparative crude protein yield (ton ha-1) of maize, sorghum and millet fodders at three vegetative stages of growth |
| Mean in the same column bearing different superscripts were significantly (p<0.05) different, *: CS1, CS2 and CS3 stand for pre heading, heading and milk stages, respectively | |
In the present study, CP yield of maize fodder was about 31% higher than that of millet fodder at milk stage. In the present study, CP yield of sorghum fodder (1.16 ton ha-1) at milk stage was comparable (1.10 ton ha-1) to that reported by Bhatti (1996).
Total Digestible Nutrient Yield
The TDN yield of millet (1.67 ton ha-1) was lower (p<0.05)
than those of maize (2.16 ton ha-1) and sorghum (1.99 ton ha-1)
fodders harvested at pre heading stage (Table 5). However,
the TDN yield of millet (4.69 ton ha-1) was higher (p<0.05) than
those of maize (4.29 ton ha-1) and sorghum (3.99 ton ha-1)
fodders harvested at heading stage. Whereas, the TDN yield of millet (8.78 ton
ha-1) and maize (8.76 ton ha-1) were higher (p<0.05)
than that of sorghum fodder (8.37 ton ha-1) harvested at milk stage.
The results of the present study in which TDN yield of maize fodder was 8.76
ton ha-1 at milk stage are substantiated by the results of Azim et
al. (2000) and Kim et al. (2001).
Influence of Maturity on Nutrient Concentration
The DM, NDF, ADF, ADL and WSC contents increased (p<0.05) as the fodders
grew in age. However, the CP, TDN and ME contents reduced (p<0.05) as the
fodders advanced in age (Table 6). The results of the present
study were concordant with those of Sarwatt et al. (1989) and Church
(1991) who reported decreased cell soluble contents and increased NDF and DM
contents with advancement in the age of fodders. Schake et al. (1982)
reported reduced CP content of sorghum as the fodder advanced in age. Church
(1991) observed that DM and fibre contents were increased from early bloom to
hard dough stage of growth of sorghum fodder, whereas, CP contents decreased
with increasing maturity of fodder.
| Table 5: | The comparative total digestible nutrient yield (ton ha-1) of maize, sorghum and millet fodders at three vegetative stages of growth |
| Mean in the same column bearing different superscripts were significantly (p<0.05) different, *: CS1, CS2 and CS3 stand for pre heading, heading and milk stages, respectively | |
| Table 6: | Dry matter, crude protein, cell wall contents, water soluble carbohydrate, total digestible nutrient and metabolizable energy (%DM) of experimental fodders at different stages of maturity |
| Mean in the same column bearing different superscripts were significantly (p<0.05) different, *: CS1, CS2 and CS3 stand for pre heading, heading and milk stages, respectively | |
Similarly, other workers (Kim and Voigtlaender, 1985; Gupta and Sagar, 1987) reported that the cell wall contents of fodder increased with the increase in their age. However, Hunt et al. (1989) and Kohan and Allen (1995) reported that concentration of NDF and ADF in whole plant of maize decreased as maturity proceeded from early one third milk line to late (black lager maturity). This decline in concentration of NDF and ADF might be due to accumulation of starch in grains. Morphological differences in cell wall contents were attributed to differences in the concentration and composition of their lignin and carbohydrate fraction in fodders (Fritz, 1989).
The present study supported the findings of Thomas and Thomas (1985) and Bolsen et al. (1992) who reported that the WSC increased as the fodder advanced in growth. However, Bolsen et al. (1983) and Havilah and Kaisar (1992) reported that average WSC contents of sorghum, wheat and barley at dough, late dough and hard grain of growth decreased, which might be due to accumulation of starch in grains. In the present study, WSC content in maize fodder at heading stage was 10.25%, which was comparable with the findings of Azim et al. (2000). Kim et al. (2001) reported that TDN value of maize fodder was higher at an early stage of growth and it decreased with increasing maturity. The reduced TDN may be because of increased cell wall contents as the plant advanced in age. Thomas and Thomas (1985) also reported that ME value of fodder crop decreased with advancing maturity of crop.
In situ Nutrients Digestibility
In situ DM, OM and NDF digestibilities of all three fodders decreased
(p<0.05) with the advancement of age at 24 and 48 h of ruminal incubation
(Table 7). The percent reduction in the digestibility of DM,
OM and NDF at 48 h ruminal incubation, was 11.10, 18.48 and 14.08%; 10.24, 11.25
and 12.18% and 12.59, 18.36 and 23.69% of maize, sorghum and millet fodders,
respectively, harvested at enhanced maturity. The results were in agreement
with those of Russel et al. (1992) and Havilah et al. (1995) who
reported that DM, NDF and OM digestibilities of maize fodder decreased with
increasing age. Similarly, Goto et al. (1991) and Cherney et al.
(1993) reported that DM, NDF and OM digestibilities of millet, oat, sorghum
and other grasses decreased with the advancement of age. Hunt et al.
(1989) reported that in situ DM digestibility of whole maize plant was
53.7% at an early maturity after 24 h of ruminal incubation. This value was
close to the DM digestibility of maize fodder (53%) incubated for 24 h, when
harvested at an early maturity in the present study. Fariani et al. (1994)
reported that rumen degradation of DM reduced (p<0.05) with advancing age
of the grass. The reduced DM and NDF digestibility of matured fodders can be
ascribed to the reduced leaf-to-stem ratio (more stem, fewer leaves) because
a greater portion of the total DM and NDF was associated with stem tissue.
| Table 7: | Effect of type of fodder and stage of age on in situ digestibility in sheep |
| Means in the same column bearing different superscripts were significantly (p<0.05) different, *: CS1, CS2 and CS3 stand for pre heading, heading and milk stages, respectively | |