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Adeola, O., D. King, and B.V. Lawrence. 1996. Evaluation of pearl millet for swine and ducks. p. 177-182. In: J. Janick (ed.), Progress in new crops. ASHS Press, Alexandria, VA.

Evaluation of Pearl Millet for Swine and Ducks*

Olayiwola Adeola, Dale King, and Bradley V. Lawrence


  1. NUTRIENT PROFILE OF MAIZE VERSUS PEARL MILLET
  2. SWINE
    1. Digestibility of Nutrients in Pearl Millet for Pigs
    2. Growth Performance Response of Nursery and Growing Pigs
  3. DUCKS
    1. Utilization of Nutrients in Pearl Millet for Ducks
    2. Growth Performance and Carcass Composition of Ducks Fed Diets Containing Pearl Millet
  4. SUMMARY
  5. REFERENCES
  6. Table 1
  7. Table 2

Pearl millet (Pennisetum glaucum) is a cereal grain with good drought tolerance and hardiness commonly grown in the semiarid regions of Africa and Asia on an estimated 26 million ha primarily for human consumption (Andrews and Kumar 1992). In addition to drought tolerance and hardiness, pearl millet has a relatively short growing season, which makes it a potential crop that can be double-cropped after wheat has been harvested so that valuable soil is not allowed to lay idle prior to the following cropping season. Pearl millet could fill the niche during periods when maize production is affected by unseasonable weather. The energy density of pearl millet is relatively high, arising from the higher oil content of this grain relative to maize, wheat, or sorghum (Hill and Hanna 1990; Sullivan 1990; Haydon and Hobbs 1991). Sullivan (1990) also reported that pearl millet usually has a superior amino acid profile and a higher protein content than maize. Research investigating the utility of pearl millet in livestock diets is limited. In broiler diets, pearl millet could replace maize without adversely affecting weight gains or feed efficiency (Singh and Barsaul 1976; Sharma 1979; Smith 1989; Sullivan 1990). Pearl millet also has the potential for use in diets of swine (Haydon and Hobbs 1991) and beef cattle (Hill and Hanna 1990). This communication summarizes the results of a series of studies conducted to evaluate the nutritional value of pearl millet in diets of pigs (Lawrence 1995) and ducks (Adeola 1994).

NUTRIENT PROFILE OF MAIZE VERSUS PEARL MILLET

Nutrient profiles of maize and pearl millet grain used in studies conducted at Purdue is presented in Table 1. Pearl millet contains 27 to 32% more protein than maize, higher concentrations of essential amino acids, two times as much ether extract, and a higher gross energy value than maize. Pearl millet has been shown to have a higher protein content and higher essential amino acid, and ether extract compared with maize (Burton 1972; Ejeta 1987; Smith 1989) sorghum, wheat, and triticale (Ejeta 1987; Smith 1989; Haydon and Hobbs 1991). The higher oil content would account for the higher gross energy value of pearl millet (Table 1).

SWINE

Digestibility of Nutrients in Pearl Millet for Pigs

In nutrient digestibility studies with 20-kg pigs, dry matter digestibility was higher for maize (87%) compared with pearl millet (77%). Protein digestibility (70%) and retention (57%) were similar between the maize and pearl millet. The ileal digestibility of most amino acids from maize seems to be similar to the values obtained for pearl millet (Haydon and Hobbs 1991), thus supporting the similar protein retention values for maize and pearl millet. Energy digestibility was lower for pearl millet (75%) than for maize (86%); and in conjunction with a lower dry matter digestibility, resulted in lower digestible and metabolizable energy values for pearl millet (2.92 and 2.84 kcal/g, respectively) than for maize (3.17 and 3.08 kcal/g, respectively). Haydon and Hobbs (1991) reported that the energy value of pearl millet was lower than that of soft red wheat, while Lin (1987) reported that the energy digestibility of hard red wheat was lower than maize, suggesting, that when fed to pigs, maize has the highest digestible and metabolizable energy values, with wheat having a lower value than maize, but a higher value than pearl millet. With increasing pearl millet inclusion, the gross energy value of the diet would increase while the supply of digestible energy and metabolizable energy would decline. The higher protein/amino acid content of pearl millet would indicate that equal-weight substitutions of pearl millet for maize could result in an increase in the supply of total amino acids for growth.

Growth Performance Response of Nursery and Growing Pigs

Growth performance responses were investigated for 28 days in nursery (10-kg) and growing (20-kg) pigs fed diets in which pearl millet was substituted for maize on a weight-for-weight basis. Growth rate of during the first 14 days and over the entire 28-day period was unaffected by dietary weight-for-weight replacement of maize with pearl millet in nursery pigs. From day 14 to 28, however, growth rate and feed intake increased quadratically to increases in substitution of pearl millet for maize with the maximum rate of weight gain achieved when 25% of the maize was replaced with pearl millet. The substitution of pearl millet for maize on a weight-for-weight basis in growing pigs did not affect growth rate, feed intake, or feed efficiency. Body weights were similar across dietary treatments at the end of the 28-day experiment.

The value of a higher amino acid composition of pearl millet relative to maize would be better tested when pearl millet- and maize-based diets are compared on an equal digestible amino acid basis. Because amino acids and energy are closely related, lysine, the first-limiting amino acid in cereal-based diets for pigs is more appropriately expressed in terms of lysine:digestible energy ratio. Lawrence (1994) determined the optimum ratio to be 3 g of lysine/Mcal of digestible energy. Based on 80% ileal lysine digestibility, this translates to 2.4 g of digestible lysine/Mcal of digestible energy. For optimum pig performance, dietary essential amino acids should be at the proper ratio to lysine. Based on this premise, another study was conducted to evaluate the performance of growing pigs fed two different ratios of threonine (65% or 70% of lysine) and total sulfur amino acids (60% or 65% of lysine) to lysine in maize-based compared with pearl millet-based diets.

Four diets were formulated to contain 2.4 g of digestible lysine/Mcal of digestible energy. Diet 1 was maize-based and formulated to contain digestible valine, isoleucine, tryptophan, total sulfur amino acids, and threonine at the optimum ratio (68%, 60%, 18%, 60%, and 65%) to digestible lysine developed by Chung and Baker (1992). Diet 2 was pearl millet-based and formulated to contain digestible valine, isoleucine, tryptophan, total sulfur amino acids, and threonine at the optimum ratio (68%, 60%, 18%, 60%, and 65%) to digestible lysine developed by Chung and Baker (1992). In Diets 1 and 2, the ratios of the digestible levels of other essential amino acids to digestible lysine exceeded the optimum ratio in the pattern for pigs (Chung and Baker 1992). Diets 3 and 4 were maize- and pearl millet-based diets, respectively; and formulated to contain digestible SAA and threonine at ratios of 65% and 70% of lysine, respectively.

The average daily gain, feed intake and feed efficiency are given in Table 2. Increasing the threonine and sulfur amino acid relative to lysine had no effect on the average daily gain, feed intake, feed efficiency, or days on feed. However, average daily gains were higher (P < 0.05) in the maize-based diets (1.07 and 1.08 kg/d vs. 1.01 and 1.02 kg/d) than pearl millet-based diets and pigs took between 1.5 and 2 days longer to reach the 50 kg live weight with the pearl millet-based diets. This apparent superiority of maize-based diets over pearl millet-based diets in supporting weight gains may be due to palatability of the feeds as pigs on the maize-based diets consume in general more feed per day. Furthermore, feed efficiency was found to be similar (P>0.05) between maize-based and pearl millet based diets.

In this study, regardless of whether diets were maize- or pearl millet-based, pigs within the 20 to 50 kg growth phase performed better on the diets formulated to contain digestible threonine and sulfur amino acids at 65 and 60% of digestible lysine than on the diets contain digestible threonine and sulfur amino acids at 70 and 65% of digestible lysine. In a previous experiment Wang and Fuller (1990) investigated the effect of the plane of nutrition on the optimum dietary amino acid pattern for growing pigs. They used six diets based on maize and soy bean meal. They reported the optimum ratio of four amino acids for 25-50 kg pigs as lysine 100, threonine 64, methionine + cystine 61 and tryptophan 20. The present study is in agreement with observations reported by Wang and Fuller (1990). It is our opinion that the lower feed intake of pearl millet-based diets when compared to maize-based diets accounted for the lower gains since feed efficiency was similar. Higher intakes of pearl millet-based diets will have the added advantage of requiring less amino acid supplementation over maize-based diets.

DUCKS

Utilization of Nutrients in Pearl Millet for Ducks

Nutrient utilization of diets containing pearl millet was investigated with 22-day-old ducks that weighed 1.2 kg. Dry matter in diets containing maize was less well utilized than that in the diets containing pearl millet. The diets containing maize had lower energy retention values than those containing pearl millet. Thus, higher apparent metabolizable energy values were observed for diets containing pearl millet than those containing maize (3.3 vs. 3.1 kcal/g). The higher metabolizable energy value of the diets containing pearl millet is in conformity with its higher ether extract content compared to maize. Feed consumption was similar across diet comparisons, but the caloric value of diets containing pearl millet was higher than those containing maize. This observation is an indication that a compensatory increase in feed intake to overcome a decrease in energy content of the diet does not always occur.

The apparent metabolizable energy content of the diets containing maize determined in the nutrient utilization study are similar to values calculated using published (NRC 1984) values for composition of feedstuffs. Using NRC (1984) values for pearl millet underestimated the apparent metabolizable energy contents of diets containing pearl millet by ca 0.77 kcal/g. In an experiment on feed grain utilization in broiler diets, Sharma (1979) reported that pearl millet had lower metabolizable energy than maize, an observation that is contrary to the results of the present nutrient utilization studies. The fact that broilers were used in their experiments, that the ether extract content of maize (3.7%) and pearl millet (4.3%) were similar, and that the level of protein meal used in their experiments were higher than that used in the present experiments may be responsible for the disparity.

Growth Performance and Carcass Composition of Ducks Fed Diets Containing Pearl Millet

In 3-week growth performance studies with day-old ducks, maize and pearl millet were compared on an equal-protein basis or on an equal-weight basis. At the end of the second week of the study, the maize diets compared on an equal-protein basis were significantly superior to the millet diets in promoting weight gain. When compared on an equal weight, the pearl millet diets were equal to the maize diets in promoting growth during the first 2 week of the experiment. Furthermore, there were no significant differences in weight gain over the 3-week period between the maize and the pearl millet diets. Feed intake during the 3-week period of the experiment was higher in ducks that received maize, than those that received pearl millet diets. In a second 3-week growth performance experiment, ducks that received pearl millet were more efficient in converting feed to body weight gains than those that received the maize diets. This is similar to the observations reported by Smith (1989) in broiler experiments where replacement of maize with pearl millet improved the efficiency of feed conversion, an improvement that was attributed to an increase in the metabolizable energy contents of diets that contained pearl millet. Carcass protein of ducks that received the diets containing maize was greater than in ducks that received the diets containing pearl millet. The maize-pearl millet comparison for other carcass components (dry matter, ether extract, and ash) was not statistically significant.

SUMMARY

Grain pearl millet is higher in protein, amino acids, ether extract, and gross energy than maize. However the digestible and metabolizable energy values are lower in pearl millet than maize when fed to pigs. Replacement of maize with pearl millet on an equal-weight basis in the diets of young pigs has no adverse effect on growth performance, other than slight increases in gain and feed intake. The use of pearl millet in diets formulated on an equal digestible amino acid basis results in slower growth rate than maize-based diets. In duck diets, pearl millet appears to have a similar feeding value to maize when substituted for maize on an equal-weight basis. In contrast to pigs, pearl millet diets have higher metabolizable energy than those containing maize. Equal-weight replacement of maize with pearl millet in the diets of ducks has no adverse effects on weight gains.

REFERENCES


*This research was supported by the Indiana Business Modernization and Techology Corporation.
Table 1. Nutrient composition of maize and two samples of pearl millet on a dry matter basis

Pearl millet
Variable Maize Nebraskaz Indianay
Dry matter (%) 88.9 89.2 89.1
Ether extract (%) 3.0 6.9 6.2
Neutral detergent fiber (%) 14.5 18.2 15.3
Acid detergent fiber (%) 2.9 4.1 4.1
Ash (%) 5.7 6.7 6.1
Gross energy (kcal/g) 4.33 4.53 4.52
Crude protein (%) 8.4 11.5 12.5
Essential amino acid (%)
Histidine .21 .27 .29
Isoleucine .39 .59 .68
Leucine .95 1.03 1.16
Lysine .23 .35 .36
Methionine .17 .23 .23
Phenylalanine .40 .54 .59
Threonine .27 .41 .44
Tryptophan .07 .19 .21
Valine .39 .58 .64
zPearl millet grown at the University of Nebraska, Lincoln, Nebraska.
yPearl millet grown at Purdue University, West Lafayette, Indiana.


Table 2. Performance of growing pigs fed two different amino acid patterns in maize-based and pearl millet-based diets.

Dietz Initial weight (kg) Final weight (kg) Daily gain (kg/d) Daily feed (kg/d) Gain/feed (kg/kg) Days on feed Number of pigs per diet
1 19.47 52.33 1.07ay 2.45ab .44 30.75bc 12
2 19.55 52.00 1.01b 2.22b .46 32.25ab 12
3 19.25 51.98 1.08a 2.54a .46 30.05c 12
4 19.23 52.27 1.02b 2.21b .46 32.50a 12
SD .6 1.29 .07 .30 .05 2.04
z Diet 1 was maize-based and formulated to contain digestible valine, isoleucine, tryptophan, total sulfur amino acids, and threonine at 68%, 60%, 18%, 60%, and 65%, respectively of digestible lysine. Diet 2 was pearl millet-based and formulated to contain digestible valine, isoleucine, tryptophan, total sulfur amino acids, and threonine at 68%, 60%, 18%, 60%, and 65%, respectively of digestible lysine. Diets 3 and 4 were maize- and pearl millet-based diets, respectively; and formulated to contain digestible total sulfur amino acids and threonine at ratios of 65 and 70% of lysine, respectively.
yMean separation in column by Neuman-Keuls' test, 5% level.


Last update June 5, 1997 aw