Liveweight gain of growing cattle offered maize meal or citrus pulp as supplements to diets based on poultry litter and restricted grazing of low quality pastures

G Nouel and J Combellas

Universidad Central de Venezuela, Facultad de Agronomía, Maracay, Venezuela
jcombell@telcel.net.ve

Two experiments were carried out to evaluate the inclusion of a high proportion of poultry litter in the diet, mixed with citrus pulp or maize meal with or without a flavouring, and its effects on live weight (LW) gain of growing cattle grazing poor quality pastures at the end of the rainy season (E1) and during the dry season (E2). A third experiment (E3) was carried out with rumen fistulated animals to study the effect of these diets on some characteristics of rumen fermentation. In E1, 42 Bos taurus x Bos indicus males of 209 ± 33 kg were used to compare three treatments receiving in pens a mixture of 79% poultry litter, 1% common salt and 20% of citrus pulp (P) or maize meal with 0.05 % of a commercial flavouring (MF) or without it (M). All groups grazed during 16 h paddocks with standing forage of 3.72 ± 1.38 tonnes DM/ha in which Hyparrenia rufa and Trachypogon gracilis predominated. The remaining time the animals were stall-fed the experimental feeds in groups during 84 days. For P, M and MF daily intakes were 1.02, 1.45 and 1.36 kg DM/100 kg LW and LW gains were 0.51, 0.59 and 0.56 kg/day (P>0.05). The same diets were used in E2, but the paddocks were accidentally burned before the trial. The grazing periods were reduced to 8 h and 36 animals of 229 ± 26 kg were used. Standing forage of the regrowth was 1.24 ± 0.42 ton DM/ha. For treatments P, M and MF daily intakes were 2.02, 2.17 and 2.07 kg DM/ 100 kg LW and LW gains were 0.31, 0.53 and 0.48 kg/day (P<0.01). The differences between treatments observed during the dry but not at the end of the rainy season, could be related to the higher mixture intakes in the second trial and their effect on total energy consumption.

The same treatments were compared in E3 and an additional treatment (L) with poultry litter as the only supplement was included. A latin square was used with 4 animals of 159 ± 16 kg and periods of 17 days. The trial was carried out during the dry season and intakes per animal were measured, being higher in M and MF than P and L, with values of 3.41, 3.35, 2.18 and 1.25 kg DM/100 kg LW. No differences in rumen ammonia nitrogen concentration were observed, with mean values of 151, 156, 164 and 130 mg/litre, respectively.

Three conclusions could be derived from this study. The addition of an energy source to poultry litter in these conditions resulted in more than two-fold consumption increments. The substitution of maize meal by citrus pulp reduced LW gain during the dry season, when high levels of mixture intake were reached. And finally, the addition of a flavouring to diets based mainly on poultry litter and maize meal did not increase intake or LW gain of growing cattle.

In the mountains and valleys of the north central region of Venezuela a cattle production system has been developed in which cattle from the lowland savannas are raised and finished on diets based on native or introduced grasses and agricultural by-products. The use of poultry litter as feed for cattle during the dry season is a common practice near broiler farms and 60 % of the broiler industry is located in this region (Industria Avícola 1992).

Poultry litter is a feed rich in crude protein, but a large proportion of it is non-protein nitrogen and a readily available source of carbohydrates is required to ensure its efficient use (Daniels et al 1983; Jakhmola et al 1988). The addition of 20% maize grain to diets based on poultry litter and wheat straw almost doubled digestible energy intake of beef calves and increased the intake and utilization of the other components of the diet (Brosh et al 1993). Sources of starch, as sorghum grain and maize and rice by-products, are available but expensive and demanded by other species that make a more efficient use of them. Citrus pulp is an alternative source of energy which is widely available in the region, where more than 70 % of the country´s citrus is grown and processed.

A series of experiments were carried out to evaluate the effect of adding a flavouring to maize meal or substituting it by citrus pulp on live weight (LW) gain and some characteristics of rumen fermentation of growing cattle fed on a basal diet of poultry litter with restricted grazing of low quality grasses.

Two feeding trials and an experiment with rumen fistulated animals were carried out on a commercial farm near Miranda, Carabobo state, on hills with slopes of 10 to 30º at an altitude of 650 to 750 m. Average temperature is 24 ºC and annual rainfall is 975 mm. The soils are acid and fertility is low to medium. Native and introduced grasses are the predominant vegetation in these ecosystems, grown in well drained soils and frequently submitted to fire during the dry season. The first feeding trial (Experiment 1) began in October 1997 and finished in January 1998, corresponding to the end of the rainy season, where sparse rains occur and most grasses flourish, decreasing their quality. The second feeding trial (Experiment 2) and the experiment with fistulated animals (Experiment 3) were carried out between February and May 1998, during the dry season.

A completely randomized design was used in Experiments 1 and 2 to compare three complementary feeds with (on a dry matter basis) 79% poultry litter, 1% common salt and either: 20% wet citrus pulp (Treatment P);  or 20% maize meal with 0.05 flavouring (Treatment MF) or without it (Treatment M). The feeds were mixed every 3 to 4 days and stored in sealed polythene bags. The poultry litter had been stored in polythene bags for at least 4 weeks and wet citrus pulp was received on the farm twice a week. Maize meal is a by-product of the maize industry for human consumption and is rich in floury starch. The flavouring (Pecuaroma, Lucta S.A.) was added  according to manufacturers instructions and contained natural citrus essences and other synthetic products.

The animals grazed three paddocks of 7.1, 8.7 and 20.3 ha, for 16 hours daily (1500 to 0700 h) in Experiment 1 and for 8 hours (0700 to 1500 h) in Experiment 2, and treatments were rotated on paddocks every 2 weeks. Fourteen young Bos indicus x Bos taurus bulls of 209±33 kg initial weight were used per treatment in the first trial and 12 of 229±26 kg in the second one. The feeds were offered in two feeding troughs per group every day allowing 10 % refusal and water was available at all times from natural springs. The duration of each trial was 12 weeks.

Botanical composition was measured at the start of the first trial using the method described by Mendoza and Lascano (1984). Weight of standing forage was estimated every 4 weeks taking 8 samples from each paddock with hoops of 0.259 m². One week before the start of the second trial, from 50 to 85 % of the paddocks were burned and sampled on two occasions to measure available pasture regrowth. All samples were weighed and separated in stems, leaves and dead material, dried at 65 ºC for 48 hours and a sub-sample ground through a 3 mm screen to estimate DM disappearance at 48 h (DMD, Ørskov et al 1980). Another sub-sample was ground through a 1 mm screen to analyse the contents of DM, ash and crude protein (AOAC 1984), calcium, copper and zinc (Willis 1961) and phosphorous (Harris and Popat 1954). Poultry litter and mixture were also analysed for non-protein nitrogen (NPN, Watt and Chrisp 1973).  The animals were weighed every 2 weeks and LW gain estimated by linear regression. Analysis of variance and Tukey tests to compare means of LW gain were carried out.

A latin square arrangement (4x4) was used to compare the three treatments described before plus a fourth treatment without energy sources, with 99% poultry litter and 1% common salt (Treatment L). Four rumen fistulated young bulls of similar genotype and weighing 159±16 kg were used, grazing one paddock of 1 ha from 0700 to 1500 h and stall fed in individual pens of 1.5 m x 3.0 m the rest of the time with feeds and water offered ad libitum. Experimental periods were of 17 days, the first 6 of adaptation to diets, from day 7 to 14 to determine mixture intakes and the last 3 days for rumen measurements. Feed samples were analysed for the same fractions described in the feeding trials and DMD of a representative grass sample was estimated inserting two bags with 5 g per bag in each animal in each period. Rumen liquor samples of 30 cc were taken just before feeding and at 1, 2, 3, 4, 6, 9 and 12 hours of day 15, filtered through cheese cloth, acidified with 8 drops of sulphuric acid 97 % and stored frozen to be analysed for ammonia nitrogen (Preston 1995).

Average standing forage in Experiment 1 was of 3.72±1.38 tonnes DM/ha and only one of the nine paddock samplings was below 2.7 tonnes DM/ha. Hyparrhenia rufa (46.5±7.3%) and Trachypogon gracilis (44.8±4.2%) predominated, with smaller proportions of Andropogon angustatus (5.4±2.7%) and Melinis minutiflora and Paspalum stellatum (2 to 3%). Dead material was 0.89±0.19  tonnes DM/ha and leaf to stem ratio varied between 1.26 and 0.38 in H. rufa and between 0.91 and 0.43 in T. gracilis. Weight of standing forage was 1.24 ± 0.42 tonnes DM/ha in Experiment 2 as a result of the pasture burning. The chemical composition and DMD of stems and leaves of these grasses are shown in Table 1. Nutritive values of ingredients and mixtures used in the three experiments are shown in Table 2. The composition of mixtures was similar with exception of a higher value of NPN in P, probably as a consequence of proteolysis occurring during storage of the wet material.

Table 1: Chemical composition of grasses ( (values for CP, ash, Ca, P, Zn and Cu are expressed on dry matter basis; DMD is dry matter loss at 48 hours)
Grass	Vegetative fraction	DM %	CP %	DMD %	Ash %	Ca %	P %	Zn ppm	Cu ppm
Experiment 1
H. rufa	Stem Leaf	55.9 61.4	3.0 4.3	25.8*	8.1 9.9	0.06 0.09	0.14 0.17	85 41	21 17
T. gracilis	Stem Leaf	49.6 54.5	5.2 6.7	18.7 19.4	6.2 5.6	0.06 0.08	0.07 0.20	39 28	10 7
A. angustatus	Stem Leaf	44.8 50.0	4.4 6.2	19.5 22.0	6.8 4.5	0.02 0.05	0.13 0.15	45 43	6 10
M.minutiflora	Stem Leaf	37.0 39.1	5.7 8.4	17.9 37.1	7.3 5.6	0.04 0.09	0.15 0.24	61 89	12 24
P. stellatum	Stem Leaf	39.1 46.4	4.3 6.4	--- ---	5.5 6.3	0.04 0.09	0.08 0.10	57 36	7 7
Experiment 2
Total regrowth		47.3	9.2	33.4	13.8	0.35	0.41	49	18
H. rufa regrowth		58.2	3.1	24.0	16.2	0.09	0.35	126	23
* Total sample

Feeds used did not affect LW gains in Experiment 1 (Table 3), but differences were found in the second trial with larger gains in M and MF than in P. DM intakes shown are group averages during both trials and were from 1.0 to 1.5 and from 2.0 to 2.2 kg/100 kg LW in Experiments 1 and 2. DM intake in Experiment 3 was larger in treatments with maize meal than in treatments P and L (Table 4). Average rumen ammonia nitrogen was not affected by treatments and DMD varied between 20.9 and 28.3 %, with differences between P and the other treatments.

Table 2. Chemical composition of ingredients and mixtures (values for N*6.25, ash, Ca and P are expressed on dry matter basis;  DMD is dry matter loss at 48 hours)
Ingredient or mixture	DM %	CP %	NPN % of total N	DMD %	Ash %	Ca %	P %
Poultry litter	88.5	19.5	30.7	37.0	30.3	1.00	0.65
Citrus pulp	24.2	10.9	-	61.5	3.9	1.19	0.57
Maize meal	90.7	12.6	-	73.6	4.1	0.12	0.66
Mixtures
P	52.9	16.2	58.6	40.7	25.3	0.82	0.66
M and MF	86.4	16.8	36.6	44.3	25.7	0.82	0.64
P is mixture of poultry litter and citrus pulp; M is mixture of poultry litter with maize meal without  or with (MF) flavouring

Table 3. Liveweight gain and consumption of mixtures  (Experiments 1 and 2)
	P	M	MF	SE
End of rainy season
LW gain (kg/day)	0.51	0.59	0.56	0.032
Mixture intake (kg DM/100 kg LW)	1.02	1.45	1.36
Dry season
LW gain (kg/day)	0.31b	0.53a	0.48a	0.043**
Mixture intake (kg DM/100 kg LW)	2.02	2.17	2.07
P is mixture of poultry litter and citrus pulp; M is mixture of poultry litter with maize meal without or with (MF) flavouring
**P<0.01; SE Standard error of mean

Table 4. Mixture intake, ammonia nitrogen concentration in rumen liquor and in sacco (48 hours) DM disappearance of H. rufa (Experiment 3)
	L	P	M	MF	SE
Mixture intake (kg/100 kg LW)	1.25b	2.18b	3.41a	3.35a	0.19*
Ammonia N (mg/litre)	130	164	151	156	23.3
DMD (%)	27.4a	20.9b	26.5a	28.3a	1.60*
L is poultry ltter alone; P is mixture of poultry litter and citrus pulp; M is mixture of poultry litter with maize meal without or with (MF) flavouring
*P<0.05; SE Standard error of mean

The quality of the pastures  was very low at the end of the rainy season (Table 1). Crude protein  values were between 3 and 7% in DM, and DMD between 17 and 26% in all species analysed, with the exception of M. minutiflora that comprised less than 3 % of the pasture biomass. Calcium content was low in all species compared with the requirements of these animals (NRC 1989).  Phosphorous was higher but also deficient;. zinc and copper were adequate. Standing forage was abundant in this season, but the low proportion of leaves and their poor nutritive value did not allow a major increase of diet quality by selection. The pasture regrowth available after burning during the dry season was of better quality, but its availability was highly depressed to levels where the intake is restricted (Minson 1990). Fire, caused by fortuitous factors or human action, is a common phenomenon in the region. The nature of the standing forage and its chemical composition, observed in both seasons, is similar to results obtained on well drained lowland savannahs (San José and Medina 1977; Chicco and Godoy 1987; Tejos and Plasse, 1996).

Addition of an energy supplement to complement the poultry litter and the low quality grazed herbage resulted in an increase in the consumption of the mixtures offered in troughs in Experiment 3. There was a more than two-fold increment with maize meal, as was observed by Brosh et al (1993), giving a feed mixture intake slightly above 3 kg DM/100 kg LW. The consumption of herbage was not estimated, but the high intakes of the feed mixture implies that it was a small component of the diet during the dry season. Consumption rate was less in Experiment 2 carried out simultaneously, but group feeding in this trial could have been the reason for the decreased average intakes compared with individual feeding in Experiment 3.

Substitution of maize meal by citrus pulp decreased LW gain during the dry period, but not at the end of the rainy season (Table 3). These differences could be a consequence of the higher mixture consumption during the dry season, and the higher NPN content of the mixture when citrus pulp was used. The lower energy quality of this ingredient compared with maize meal was an additional factor. The quality of herbage was similar in both periods, but herbage availability was lower in the dry season and mixture intake was almost double compared to the other period. Higher levels of NPN in mixture P (Table 2) could be a consequence of fermentation after mixing the wet citrus pulp with the poultry litter and storing it for 3 to 4 days. McDonald (1981) has pointed out that 20 to 50% of protein is degraded after 2 to 5 days of ensiling. However, these NPN levels did not result in major differences in ammonia nitrogen concentrations in rumen liquor in Experiment 3 (Table 4), but probably the absence of differences was also explained by the lower intake of the citrus pulp diet.

Silanikove and Tiomkin (1992) have observed very high levels of ammonia nitrogen, reaching 300 to 500 mg/litre in the rumen of cows receiving more than 10 kg/day of poultry litter, associated with liver damage and a mortality rate of 10 to 20 %. The levels of ammonia found in this study were much lower, with averages between 130 and 170 mg/litre, and could be related to the lower nitrogen content of the poultry litter used.   In our trials the crude protein in the litter was 19% and was below average according to the classification of Andrade et al (1997).  In contrast,   Silanikove and Tiomkin (1992) used a source with 30% CP which is at the top of the quoted scale. Liver damage was not evaluated in the present case, but no deaths were observed. The strategy followed was to use poultry litter as a feed during periods of restricted herbage availability.

The use of a flavouring in the diet with maize increased costs but did not result in any improvement in intake (Table 4) or LW gains (Table 3) compared with the treatment (M) withiout the flavouring. This contrasts with the evidence of Tien et al (1997) that odour and flavour affected the acceptance of new supplements in grazing sheep.

• The addition of an energy source to growing cattle diets based in poultry litter and restricted low quality herbage resulted in more than two-fold consumption increments.
• The substitution of maize meal by citrus pulp to complement these diets had different effects on LW gains, according to herbage availability. No differences were found at the end of the rainy season, with abundant low quality herbage available. However, lower LW gains were observed with citrus pulp during the dry season, where herbage offer was severely restricted and poultry litter was the main component of diet.
• The addition of flavouring to diets based mainly in poultry litter and maize meal did not increase intake or LW gain of growing cattle.

The authors express their gratitude to CONICIT for the financial support (Project Nº S1-97000528)

Andrade R A de, Cruz G M de and Esteves S N 1997 Utilização de cama-de-frango na alimentação de bovinos. EMBRAPA, Centro de Pesquisa Pecuária do Sudeste. Circular Técnica Nº 10. 30p

AOAC 1984 Official Methods of Analysis (14th ed.). Associación of Official Agricultural Chemists, Washington.

Brosh A, Holzer Z, Levy D and Aharoni Y 1993 The effect of maize grain supplementation of diets based on wheat straw and poultry litter on their utilization by beef cattle. Animal Feed Science and Technology 40:165-175

Daniels LB, Smith M J, Stallcup OT and Rakes J M 1983 Nutritive value of ensiled broiler litter for cattle. Animal Feed Science and Technology 8:19-24

Chicco C and Godoy S 1987 Suplementación mineral de bovinos de carne a pastoreo. In: III Cursillo Sobre Bovinos de Carne. Eds: N Peña and D Plasse. Universidad Central de Venezuela. Facultad de Ciencias Veterinarias. Maracay. pp:47-103

Harris W Y and Popat P 1954 Determination of the phosphorus content of lipids. Journal of the American Oil Chemistry Society 31:124-127

Industria Avícola 1992 Revista Industria Avícola. Diciembre, 38(12):6-26

Jakhmola R C, Kundu, S S, Punj, M L, Singh Kiran, Kamra D N and Singh Rameshwar 1988 Animal excreta as ruminant feed- scope and limitations under Indian conditions. Animal Feed Science and Technology 19:1-23

Mendoza P and Lascano C 1984 Mediciones en la pastura en ensayos de pastoreo. In: Evaluación de Pasturas con Animales. Ed: C. Lascano and E Pizarro. Red Internacional de Evaluación de Pastos Tropicales. CIAT, Cali. pp:143-165

McDonald P 1981 The Biochemistry of Silage. Willey, Manchester. 207p

Minson D J 1990 Forage in Ruminant Nutrition. Academic Press, San Diego

NRC 1989 The Nutrient Requirements of Dairy Cattle. National Research Council, National Academy of Science, Washington, DC

Ørskov E R, de Hovell F D and Mould F 1980 The use of the nylon bag technique for the evaluation of feedstuffs. Tropical Animal Production 5:195-213

Preston T 1995 Tropical Animal Feeding. Animal Production and Health Paper Nº 126. FAO, Rome.

San José J and Medina E 1977 Producción de materia seca en la sabana de Trachypogon. Boletin de la Sociedad Venezolana de Ciencias Naturales 33:75-100

Silanikove N and Tiomkin D 1992 Toxicity induced by poultry litter consumption: effect on measurements reflecting liver function in beef cows. Animal Production 54:203-209

Tejos R and Plasse D 1996 Alternativas de pastoreo racional que mejoran la productividad del rebaño bovino de carne. In: XII Cursillo Sobre Bovinos de Carne. Eds. D Plasse, N Peña de Borssoti and R Romero. Universidad Central de Venezuela, Facultad de Ciencias Veterinarias, Maracay. pp:209-236.

Tien D, Nolan J and Hinch G 1997 Odour and flavour affect acceptance of novel supplements for grazing sheep in Vietnam. In: Recent Advances in Animal Nutrition in Australia. Ed. D. Farrell. University of New England, Armidale. p.254.

Watt G and Chrisp W 1973 The determination of urea in feedstuff. In: The Analysis of Agricultural Matter. Technical Bulletin Nº 27, MAFF, London.

Willis J 1961 The determination of calcium and magnesium in urine by atomic absorption spectroscopy. Analytical Chemistry 33:556-559

Received 23 January 1999

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