Forty eight crossbred pigs (Landrace-Duroc) averaging 11.94±1.5 kg were used to evaluate the effect of insoluble solids of nejayote (ISN) as calcium source on growing performance during six weeks. Two sources of calcium (CaCO3 and ISN),and four dietary calcium concentrations (28, 53, 77 and 100% of the NRC (1988) requirement) were used in a 2x4 factorial arrangement in a completely randomized block design. There were three blocks and three replicates (pens) by treatment and two pigs per pen. Pigs were allotted to eight pens (3x2 m with concrete floor), a gilt and a barrow per pen. Average daily gain (ADG, kg), average daily feed intake (ADFI, kg) and feed efficiency (G:F, kg/kg) were considered as dependent variables. There were no differences (p>0.1) due to calcium source or dietary calcium concentrations for ADFI, G:F and ADG. The interactions source by Ca level were also not significant. Therefore, it was concluded that the insoluble solids of nejayote did not affect the performance in growing pigs.Introduction.
In most Latinoamerican countries and specially in Mexico, corn is the most important source of food. The consumption of corn can be as processed corn (nixtamalizado) for humans or as feed for domestic animals. The process known as "nixtamalizacion" consist in exposing corn grain for 15 to 60 min to a boiling mixture of water and calcium hydroxide: after that it is cooled down for several hours and then the mixture is rinsed with clean water, producing a soft, huskless grain known as "nixtamal" for tortillas, and by product called "nejayote" containing three to five parts of water and one part of corn. For each ton of processed corn, at least three tons of nejayote are produced. In Mexico the consumption of corn processed was approximately eight million of ton. in 1996, the quantity of nejayote produced is about twenty four millions ton.
This quantity of waste waters place corn processed industry for consumption human, in the five principal liquids contaminants that produce the country. The nejayote produced during corn processing (nixtamalizacion) are not important because there are considerate a remainder product so that this waste waters are throw out to the pipe drainage or directly to the environment, causing a big problem of contamination due to the high organic matter and a high Oxygen Biochemical Demand (3000-10310 mgO2/l). A possible solution to reduce contamination is to obtain this insoluble solids which can be used as an alimentary supplement for domestic animals (chicks, pigs, ruminants, etc.) as shown by Velasco-Martinez et al., 1997.
The objective of this study was to evaluate the insoluble solids of nejayote (ISN) on growing pigs, comparing with diets supplemented with CaCO3 (standard reference) at different dietary calcium concentration, evaluating several growing parameters as Daily gain, Daily Feed Intake and Feed Efficiency.Table 1.
Experimental diets composition.a
37.451±0.212 % Calcium.c
26.263±0.495 % Phosphorus.d
Provide per kilogram of premix: 3500 UI of vitamin A, 350 UI of vitamin D, 50 UI of vitamin E, 1.58 mg of vitamin K (menadione), 16 mg of niacin, 9.5 mg of pantothenic acid, 3.16 mg de riboflavin, 0.016 mg of vitamin B12, 20 mg of Copper, 0.15 mg of Selenium, 0.71 mg of Magnesium, 63 mg of Iron, 95 mg Zinc, 24 mg of Manganese.Experimental Procedure.
The experiment was carried out at the Experimental Station "La Posta", Paso del toro, Veracruz, Mexico. The ISN were obtained following the procedure established by Velasco et al., (1997). Forty eight crossbred pigs (Landrace-Duroc) of six weeks of age were used in a 2x4 factorial treatment arrangement in a completely randomized block design. There were three replicaties per treatment with two pigs per pen. Two sources of calcium (CaCO3 and ISN), were tested at four dietary calcium concentrations (28, 53, 77 and 100% of the NRC (1988) requirement, or 0.20, 0.37, 0.54 and 0.71 % of dietary calcium concentration respectively). The CaCO3 was used as the standard reference source (Ross et al., 1984; Walker et al., 1993ab). The animals were selected by weight and randomly allotted in eight pens (3x2 m with concrete floor), a gilt and a barrow per pen, feeders were constructed of solid concrete and water supplied from stainless steel nipple waterers. During the experimental period (six weeks) the animals weighted at the initial and weekly, feed intake was determined daily by difference between the original feed furnished and that left over. Dependent variables were: Average daily feed intake, kg/day (ADFI), Average daily gain, kg/day (ADG), Feed conversion, kg/kg (F:G) and Feed efficiency, kg/kg (G:F). The experimental diets (table 1) were established on an isoenergetic and isoproteic basis using corn and soybean meal as the main ingredients for all diets. All of ISN were from the same source.
Chemical composition of insoluble solids of nejayote (ISN), corn, soybean meal and diets are given in tables 2 and 3 respectively. The chemical analysis were determined according to AOAC (1990) methods and the metabolizable energy was calculated from the Titus equation (Dale, 1990).Statistical analysis.
The data were analyzed by ANOVA using the GLM procedure of MINITAB (1995) for a 2x4 factorial treatment arrangement in a completely randomized block design. Pen was considerated the experimental unit and blocks as the replicates, initial weight was used as covariable in the analysis. The probability level used to determine significance for all data was p<0.05 unless otherwise stated.Table 2.
Chemical Composition (%)a
of corn, soybean meal and insoluble solids of nejayote (ISN).a
Dry basis. The values represent the mean of three assays ± SD.b
Metabolizable Energy (Calculated).Table 3.
Chemical composition of experimental diets.a
as fed basis. The values represent the mean of six assays. b
Metabolizable Energy (Calculated). SEM= Standard error of means. Results and Discussion.
The results for ADG (Average daily gain), ADFI (Average daily feed intake), G:F (Feed efficiency) and F:G (Feed conversion) for the whole period are presented in table 4. There were no differences (p>0.1) in any of the analyzed traits.
Several researches for performance data generally have shown that different dietary calcium and phosphorus levels have no effect on ADG, ADFI and G:F in the initial growing phase. Nimmo et al. (1980) reported that there were no differences on ADG (0.55, 0.58, 0.55), ADFI (1.17, 1.23, 1.16), F:G (2.08, 2.16, 2.10) to the different treatments (A= 0.65% Ca, 0.50% P; B= 0.975% Ca, 0.75% P; C= 1.3% Ca, 1.0% P) during the initial growing phase for boars; Crenshaw et al. (1981) demonstrated that there were no differences on growing or G:F due to sex for pigs of eight weeks of age assigned to two treatments (T1= 0.4, 0.4% Ca,P and T2= 0.8, 0.8% Ca,P). However in 1981 Nimmo et al. reported that there were not effect of treatments (A= 0.65% Ca, 0.50% P; B= 0.975% Ca, 0.75% P) on ADG and F:G but ADFI was lower (p<0.05) for the pigs assigned to the treatment A (1.87 Vs 1.95 kg). The NRC (1988) reported an expected weight gain (kg/day) of 0.450, feed intake (kg/day) of 0.950 and a efficiency (gain/feed) of 0.474 for pigs with a liveweight of 10-20 kg; so that, the values obtained in this experiment are in agreement with those reported by the NRC.
Recent researches demonstrated that exist a relationship between calcium dietary concentration and others factors that affect the performance data; Lei et al. (1994) reported that supplemental microbial phytase in corn-soybean meal diets improves phytate phosphorus utilization more efficiently at moderately low levels of dietary calcium than at normally recommended levels; Kornegay et al. (1994) studied the effects of diet acidity and protein level and its relationship with source of calcium in weanling pigs, they concluded that increasing diet acidity usually improved growth rate, but gilts and barrows tended to respond differently; Carter et al. (1996) studied the relationship between serum concentrations of osteocalcin and bone mineralization in growing pigs, they concluded that serum osteocalcin and 1,25-dihydroxyvitamin D3 concentrations are better predictors of end-measures of bone mineralization in pigs than serum alkaline phosphatase.Table 4.
Effect of insoluble solids of nejayote (ISN) and dietary calcium concentration (DCC) on the performance of growing pigs (6 to 12 weeks of age) a
Initial Weight, 11.94±1.5 kg ( P>0.1).b
Least squares means.
FW = Final weight. SEM = Standard error of means.Implications.
The use of insoluble solids of nejayote (ISN) on the diet did not affect feed intake, gain:feed or daily gain for growing pigs.References.
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