Voluntary intake and performance of ruminant animals offered poultry litter-olive cake silage

Voluntary intake and performance of ruminant animals offered poultry litter-olive cake silage

Poultry litter collected from a commercial broiler house, bedded with wood shavings, was used. The screened poultry litter was ensiled with fresh crude olive cake and ground maize grain (20:70:10). Ensiling was in an above-ground concrete silo pit. The silage was opened after 60 days of fermentation and used in trials with growing Chios ewe lambs, Damascus goat kids, Friesian heifers and mature Chios wether sheep. In all four trials the performance of animals on the silage diet was compared with those on a control diet. Apparent digestion coefficients of the actual diets consumed by the heifers were measured using Chios wether sheep.

The silage used (12.8% N x 6.5 in dry matter) had very good aroma and colour, a pH value below 5 (4.8?0.09), acceptable concentrations (mg/g) of acetic (54.2?22.3), propionic (35.7?7.23) and lactic acid (57.5?1.34) and low levels of butyric acid (4.9?1.55). Ewe lambs and wethers on the control diet were almost maintaining weight, whereas the goat kids and heifers gained weight. In contrast, ewe lambs, goat kids and heifers on the silage diet all gained weight. Differences between treatments (Control vs Silage), within animal species, were significant in ewe lambs and heifers. Ewe lambs on the silage diet performed better than those on the control diet, whereas the opposite prevailed in heifers. Dry matter and N x 6.25 digestibility of the control diet (0.49:0.51, concentrate to straw) were 64.5 and 70.1% and for the silage diet (0.44:0.12:0.44, concentrate:straw:silage) were 59.3 and 70.1%. The silage was very palatable and the corresponding daily intake (g DM/ kg^0.75) was for ewe lambs 49.2, goat kids 26.1 and wethers 55.4, respectively.

KEY WORDS: Olive cake, poultry litter, ensiling, ruminants, growth, palatability, digestibility

The use of crude olive cake, the main by-product of the olive oil industry, is limited because of its low nutritive value (Aguilera et al 1992) and seasonality. The by-product is available during the rainy season (end of November to February) in appreciable quantities in most Mediterranean countries (Sansoucy et al 1987) and cannot be fully utilised fresh. The by-product is stored in large heaps in the open where it deteriorates quickly. In an earlier observation trial carried out at our Institute (M Hadjipanayiotou, unpublished data) it was noted that voluntary intake of crude olive cake, kept in a heap (around 1.5 m height) or spread and turned every other day in a shed (in a 10-20 cm layer), was reduced with advancing storage period; the reduction becoming greater after a storage period of around 10 days.

Small-scale laboratory tests carried out at this Institute (M Hadjipanayiotou and D Hadjidemetriou, unpublished data) showed that crude olive cake can be safely stored for a considerable time when ensiled either alone or in combination with other conventional (maize grain, molasses) or non-conventional materials (poultry litter).

The present study was undertaken to study voluntary intake of crude olive cake, ensiled with poultry litter and ground maize, by growing Chios ewe lambs, Damascus goat kids, Friesian heifers and mature Chios wether sheep and to compare the performance of these animals with those on a conventional diet.

Poultry litter collected from a commercial broiler house, bedded with wood shavings, was used. The poultry litter was screened using a 20 mm metal grid to remove pieces of wood and caked material. The poultry litter was a mixture of bird excreta, wasted feed, bedding and feathers. The silage was prepared in an above-ground concrete silo pit (1.6 x 2.9 x 1.1 m). It was composed of 70% fresh crude olive cake, 20% screened poultry litter and 10% ground maize grain.

Crude olive cake is the residue obtained at the mill after extracting the oil by pressing or centrifuging the whole olive fruits. The ingredients were placed in alternate layers, the first and the last layers being crude olive cake. The poultry litter and ground maize grain were roughly mixed and placed as a single layer. Water (30 litres/100 kg mixture) was added to raise the moisture content to about 50%. On top of every three layers of crude olive cake, poultry litter/ground maize, the material was pressed using an electric vibrator. The pressed material was covered using black polyethylene sheet. A thin layer of soil (3-5 cm) was placed over the plastic sheet. Preparation of silage was made in one day and the silo was opened after a fermentation period of 60 days.

Representative samples of the ingredients used were taken prior to ensiling and proximate analyses were made on dried (65 C) ground (1 mm sieve) samples as outlined by Harris (1970). Silage dry matter content was determined twice a week by drying to constant weight in an air forced oven at 105 ?C for two days. Silage analyses for total N, NH₃-N, fatty acids and pH were made once weekly on a fresh sample. NH₃-N and pH measurements (Hadjipanayiotou 1982b) of silage were made on a water extract prepared by homogenizing 25 g of fresh silage with 100 ml water in a blender at full speed for 4 min. The contents were filtered through two layers of cheese-cloth prior to determination of pH, NH₃-N and lactic acid (MAFF 1973). The extract for acetic, propionic and butyric acid determination was prepared by mixing 25 g of fresh silage with 50 ml of 0.05-N H₂SO₄; the mixture was allowed to stand in a freezer (4 ?C) for seven days and shaken once daily. At the end of the 7th day the mixture was strained through two layers of fine muslin. One ml of pivalate solution (40 g/l) was added to 10 ml of the filtrate and mixed thoroughly in a vortex mixer. To 4 ml of this mixture one ml of H3PO₄ solution (1 mmol/ml) was added, and the mixture centrifuged at 2000 rpm for 10 min. The supernatant was used for acetic, propionic and butyric acid measurements in a Varian Gas Chromatograph 3300 fitted with flame ionization detector. The glass column (180 cm length and 1.4 mm internal diameter) was packed with GP 10% SP-1000, 1% H₃PO₄ and 100/120 chromosorb W-17W.

Residues were collected daily and analyzed twice a week for dry matter; analyses on residues for N, in vitro digestibility, crude fibre and ash were made in duplicate on a single bulk sample. Digestibility in vitro was determined by the procedure described by Tilley and Terry (1963) as modified by O'Shea and Wilson (1965). Sample processing and analyses for acetic, propionic, butyric and lactic acid and NH₃-N were made as outlined by Hadjipanayiotou and Hadjidemetriou (1994). Data collected within trials were analyzed by one way analysis of variance. The mean group intakes (g/kg^0.75) every four or five days were used as individual observations (n=9) for animal species comparisons for silage voluntary intake.

HEIFERS: Sixteen young Friesian heifers were divided into two uniform groups based on their body weight and age. The two groups were randomly allocated to a control or a treatment diet (silage). The animals were group-housed in two adjacent yards with fenced type feeders with sufficient space allowing all animals to eat at the same time. The present trial was conducted simultaneously with other trials with Chios ewe lambs, with Damascus goat kids and with mature Chios wether sheep. Heifers on the control diet were offered a concentrate mixture, green barley forage and straw. In the silage diet, 2 kg of fresh silage (50% DM) were offered as replacement for 100 g concentrate and 900 g straw. The concentrate mixture was composed (g/kg) of 758 barley grain, 170 soybean meal, 50 wheat bran, 2.5 dicalcium phosphate, 14 limestone, 3.5 sodium chloride and 2 vitamin-trace element mixture (Vita 6, Vita-trace Nutrition, Cyprus). The vitamin-trace element mixture supplied 6000 IU vitamin A, 1000 IU vitamin D3, 8.5 IU vitamin E, 25 mg Mn, 1.75 mg I, 45 mg Zn, 30 mg Fe, 2 mg Co and 60 mg per kg concentrate mixture (as fed basis). Samples collected once a week during the test period and at ensiling were subjected to a microbiological analysis (Listeria monocytogenes, IDF 1990; Salmonella sp., WHO 1990; Clostridium sp.- including botulism, Wilson and Miles 1966) immediately after collection.

Animals were weighed at the beginning, one month later and at the end of the 42-day trial. Heifers had free access to water.

GOAT KIDS: Twenty Damascus goat kids were divided into two uniform groups based on their body weight and age. The two groups were randomly allocated to either the control or the silage diet. The two groups were housed in two adjacent pens and had free access to water. The goat kids on the control diet were offered a diet of concentrate and barley hay (65:35) to attain a growth rate of 100 g daily (MAFF 1975). In the silage group, animals were offered 70% of the daily allowance of the control diet plus silage ad libitum. Feed residues were collected daily. Kids were weighed at the beginning, in the middle and at the end of the 42 day trial. The concentrate mixture was composed (g/kg) of 821 barley grain, 107 soybean meal, 50 wheat bran, 3 dicalcium phosphate, 13 limestone, 4 salt and 2 "Vita 6".

EWELAMBS: Twenty Chios ewe lambs were used. Allocation of animals to treatments was as outlined in the kid trial. Daily feed allowance on the control diet was somewhat lower (to gain 50 g/day) than that of kids. Records taken and processing were identical to those of the kid trial. The ewe lambs were offered the goat kids' concentrate mixture at the same proportion with barley hay.

CHIOS WETHER SHEEP: Eighteen mature Chios wether sheep were divided into two uniform groups and randomly allocated to a control or a silage diet. Animals on the control diet were offered a concentrate mixture (similar to the one used for lambs and kids) and straw to meet their maintenance (Economides 1986) energy requirements. Animals on the silage group were offered 0.7 of the daily feed allowance offered to the control group plus silage ad libitum. Animals were housed in two adjacent pens and had free access to water. The wethers were weighed at the beginning and at the end of the 42-day trial. Feed recording and processing were similar to the other two trials.

DIGESTIBILITY STUDY: Apparent digestion coefficients of the two diets fed to the Friesian heifers were determined using four mature Chios wether sheep per diet. Animals on both diets were fed at 1 x Maintenance energy requirements. Wethers were given the experimental diets for 14 days before being placed in metabolic crates for another 14 days. The first seven days served as adaptation period and the last seven days for the faecal and urine collection period. Collection, processing and analyses of feed, faeces and urine samples were as outlined by Hadjipanayiotou (1982a).

The chemical composition of the conventional feedstuffs and of the silage used is given in Table 1. The silage had very good aroma and colour.

Table 1: Proximate constituents and in vitro digestibility values of feedstuffs (g/kg DM)

	DM	N x 6.25	Ash	EE	NDF	ADF	Dig


Concentrate#	883	198	76	70	220	85	840
Concentrate##	865	164	49	75	225	89	830
Straw	857	39	90	448	ND	480	440
Barley hay	893	105	94	290	525	320	580
Silage	505	128	55	ND	ND	ND	258
Crude olive cake	497	47.7	13	98	694	522	119
Poultry litter	908	279	116	47	384	216	502

## Concentrate used in the trials with ewelambs, goatkids, wethers; ND Not determined; Dig Digestibility of organic matter in the dry matter (%) (after Tilley and Terry 1963)

Some silage characteristics (mean of 13 for pH, NH₃-N or 7 for microbiological assay, fatty acids) of samples collected at regular intervals during the course of the 42-day test period were: pH 4.8?0.09, NH₃-N 13.2?1.34 mg/100 ml, acetic acid 54.2?22.30 mg/g DM, propionic acid 35.7?7.24 mg/g DM, butyric acid 4.9?1.55 mg/g DM, lactic acid 57.5?1.34 mg/g DM. There was no sign of mould; microbiological analyses (Salmonella, Listeria, Clostridium) on the ingredients used (Poultry litter, Crude olive cake, Maize grain) and on the silage were all negative. All animals used on the two diets were healthy throughout the 42-day test period.

Table 2: Mean values for liveweight change and feed intake of Chios wether sheep given a conventional diet or one with partial replacement by silage made from olive cake, poultry litter and ground maize grain (7:2:1)

	Control	Silage	SE/Prob

Liveweight (kg)
Initial	66.1	66.6	3.55/NS
Final	65.8	66.8	3.79/NS
Weight change (g/day)	-5	5	37/NS
Feed intake (g/day)
Concentrate	705	501
Straw	446	369
Silage (fresh)	-	2398
Silage (dry basis)	-	1270

The proximate composition of the silage was related to the composition of the straight ingredients. Chios wether sheep on the control and silage diets maintained their weight (Table 2). Ewe lambs on the control diet almost maintained their body weight, whereas, those on the silage diet were gaining weight (Table 3); differences in weight gain between the two diets were significant (P<0.01). Feed intake by ewe lambs and goat kids is in Table 3 and that of mature Chios wethers and growing Friesian heifers in Tables 2 and 4, respectively. DM intake (g/kg^0.75) on the control diet was 69.5 and 53.9 in goat kids and ewe lambs, respectively. DM intake (g/kg^0.75) of the silage diet was also higher for kids (48.8) than for lambs (38.2 g/kg) than on the S diet. Silage intake (g/ kg^0.75) by kids was significantly lower (P<0.01) than that of lambs (kids 26, lambs 49). There was no difference in silage DM intake between ewelambs and Chios wethers (55.4 g DM/kg^0.75)

Table 3: Mean values for weight change and feed intake of Chios ewe lambs and Damascus goat kids given a conventional diet (Cont) or one with partial replacement (30%) by silage (Sil) made from olive cake, poultry litter and ground maize grain (7:2:1)

	Ewe lambs			Goat kids
	Cont	Sil	SE	Cont	Sil	SE

Liveweight (kg)
Initial	42.6	42.7	1.40	34.5	34.5	0.98
Final	41.5	44.7	1.53	36.5	36.2	1.30
Change (g/day)	-27	53	16	46	39	11
Feed intake (g/d)
Concentrate	580	410		660	460
Cereal hay	310	220		350	250
Silage (Fresh)		1457			787
Silage (Dry basis)		733			377

Table 4: Mean values for weight change and feed intake of Friesian heifers given a conventional diet or one with partial replacement by silage made from olive cake, poultry litter and ground maize grain (7:2:1)

	Control	Silage	SE/Prob

Liveweight (kg)
Initial	325	323	30/NS
Final	344	333	33/NS
Daily gain (g)	444	235	98/NS
Feed intake (kg/day)
Concentrate	3.0	2.78
Straw	3.0	1.05
Silage (Fresh)		4.73
Silage (Dry basis)		2.39

Apparent digestion coefficients of the diets by Chios wethers are given in Table 5. The silage diet had significantly lower digestibility values for dry matter (P<0.01), organic matter (P<0.01) and in vitro organic matter (P<0.03) than the control. As was planned, wethers on the silage diet consumed significantly less (P<0.05) concentrate and straw but they consumed more silage.

Table 5: Mean value for digestion coefficients of a conventional and a silage made from olive cake, poultry litter and ground maize grain (7:2:1)

	Digestibility (%)
	Control	Silage	SE

Dry matter	64.5	59.3	0.82
Organic matter	67.1	61.6	0.82
N x 6.25	64.9	70.1	0.95
Feed intake (g DM/d)
Concentrate	525	465	7.9
Straw	554	132	7.6
Silage		470

In line with previous studies (Fontenont 1981; Hadjipanayiotou 1984; Hadjipanayiotou et al 1993) no disease problems were encountered from feeding poultry excreta silage to ruminant animals. The pH of the silage was below 5 a value that has been proposed by McCaskey and Anthony (1975, cited by Roothaert et al 1992) as destroying Salmonella and other pathogens. The silage had a pleasant aroma and good colour as has been shown by other researchers when poultry litter was ensiled with forage maize (Harmon et al 1975), citrus pulp or weeds (Hadjipanayiotou 1982) and/or sugarbeet pulp (Hadjipanayiotou et al 1993). There was no significant difference in the chemical composition of silage offered and refused indicating that there was no apparent selection of any of the ingredients used.

The silage was very palatable despite its rather low energy density. The consumption of the silage (g DM/kg^0.75) by ewe lambs and wethers was higher than that by goat kids (ewelambs 49.2, wethers 55.4 and goatkids 26.1). Higher voluntary intake of poultry litter/citrus pulp silage by lambs than by kids was also reported by Hadjipanayiotou (1993). It must be underlined, however, that the consumption of silage in the present studies was significantly higher, and the lower intake of silage by kids can be partially ascribed to the higher intake of conventional feedstuffs by kids than lambs. High intake (509 gDM/lamb/day) of poultry litter/crude olive cake/wheat bran silage (45:45:10) by fast-growing lambs has also been reported by Kayouli et al (1993). With the exception of the dry matter content there was no other difference in the chemical composition of silage offered and refused indicating that there was no apparent selection by animals of any of the three ingredients. The higher DM content of silage refused than offered was probably due to evaporation of moisture.

In the silage group the consumption of 733 g silage DM/ewe lamb daily resulted in 80 g more body weight gain compared to the control diet, despite a lower intake of concentrate and barley hay.

Although the ewe lambs and goat kids were fed to gain 50 and 100 g body weight daily, the actual weight gain was less and this can be ascribed to the fact that their energy requirements might be greater than those proposed by MAFF (1975), and/or the energy content of the feedstuffs was lower than had been predicted, or simply that the standards are not appropriate for use with unconventional diets as proposed by Preston and Leng (1987).

It is concluded that the ensiling process is an effective, simple and low-cost technique for preserving crude olive cake. Ensiling of crude olive cake with poultry litter gives a final product balanced in terms of nitrogen, macro/micro minerals and of higher digestibility than that of the constituent ingredients. Such a product can make a significant contribution to livestock production, not only as replacement for scarce roughage in dry periods of the year, but also as part of a total mixed ration in intensive operations.

The author is grateful to his colleagues A P Mavrogenis and Ch. Papachristoforou and to Rene Sansoucy for reviewing the manuscript; to M Papaprodromou and his staff for carrying out the microbiological analyses; and to L Hadjiparaskevas, G Kyprianou, A Photiou and M Karavia, M Theodoridou and the staff of the Central Chemistry Laboratory for skilled technical assistance.

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