Material and methods
Results
Conclusions
Bibliography
M.G. Elhag and H.H. ElkhanjariThe authors' address is: Rumais Livestock Research Station, Ministry of Agriculture and Fisheries, PO Box 467, Muscat, the Sultanate of Oman.
The quantity and quality of water are limiting factors in crop and forage production in almost all Arabian Gulf countries, particularly in the Sultanate of Oman. In the southern part of the country, livestock depends predominantly on natural pastures and range, with the addition of some imported raw feed ingredients that are processed locally into concentrates. Feed shortage is the major factor affecting the development of the country's animal industry (El Hag, 1989). However, there are many non-conventional feeds and by-products available that could be used to improve this situation. For example, the annual production of sardines has been estimated to be about 25000 tonnes. In addition, rejected dates and date by-products in the form of pips and leaves are available in promising quantities. It has been estimated that there are over 8 million date trees in the sultanate. However, only 5 million trees are productive, with an annual production of approximately 85000 tonnes of dates. About 10000 tonnes are of inferior quality and are fed to ruminants (B. Namroud, personal communication, 1990). Date byproducts could also be used as animal feed. The annual dry matter (DM) yield of date pips and date leaves is slightly more than 15000 and 30000 tonnes, respectively.
The objective of this study is to evaluate the feeding value of both dates and their by-products (leaves and pips) and sardines as protein supplements for growing calves and goats. The results could promote the utilization of locally available and cheaper agro-industrial by-products for feeding ruminants in the Sultanate of Oman.
Two trials were conducted to evaluate the nutritional value of dates and date by-products, supplemented with sardines, as potential feed resources for growing ruminants. In Trial 1, the nutrient composition and feeding value of dates and sardines for growing dairy calves were evaluated, while Trial 2 involved the evaluation of date by-products (leaves and pips) together with sardines in a pelleted diet for growing goats.
Trial 1: The feeding value of dates and sardines for growing dairy calves
Animals. Six male and four female local zebu dairy calves between 51 and 83 kg live weight and from six to eight months of age were used in this study. All the calves were born at the dairy unit of the Rumais Livestock Research Station. They were fed a commercial milk replacer and weaned at the age of three months. After weaning and until the beginning of the study the calves were fed a commercial calf ration containing 18 percent crude protein (CP) and Rhodes grass hay (Chloris guyana), ad libitum.
Experimental design. The calves were divided into two groups of three males and two females each. The mean live weight of the calves in each group was: 71.4 ± 11.9 kg and 71.6 ± 12.7 kg, respectively. The groups were allocated at random to either a barley-based diet or a diet based on dates. The calves were weighed every two weeks, before the morning feed. The trial lasted for 98 days.
Experimental diets. The experiment involved two diets. The first was based on 40 percent air-dried ground barley, 40 percent commercial 18-percent CP calf ration and 20 percent sun-dried sardines. The second consisted of the same ingredients in the same proportions, except that dates replaced the ground barley. In the case of the first diet, the three feed ingredients - barley, commercial calf ration and sardines - were weighed, mixed daily and fed together, ad libitum, in one trough. Rhodes grass hay was also added to both diets, ad libitum, in a separate rack designed for this purpose. For the date-based diet, the dates were fed in a separate trough, while the sardines and the calf ration were mixed together daily and fed in a separate trough.
The chemical composition of the feed ingredients is given in Table 1 and the final dry matter (DM) compositions of the diets are presented in Table 2. Calves on both diets were allowed free access to salt-licks. In Table 3, the proximate analyses and the nutritive value of the diets are given.
Feeding and management. The calves in both treatments were managed as one group and housed in a large pen equipped with adequate feeding and water facilities. The diets were offered once a day at 07.30; the excess collected and weighed before the following day's ration was offered. Samples of the diets were collected once a week for chemical analysis, which was done in accordance with the standards of the Association of Official Agricultural Chemists (AOAC, 1984). The cost of feeding was computed on the basis of the prevailing prices for the local ingredients.
Trial 2: The feeding value of date by-products (leaves and pips) and sardines for growing goats
Animals. Twenty local long-haired male Batina kids, between 14 and 23 kg and eight to nine months of age, were used in this study. All kids were weaned at three months of age, following full suckling of their dams, in addition to having access to a pelleted 15-percent CP feed. After weaning, they were fed 0.5 kg per head per day of the same pelleted diet, together with Rhodes grass hay fed ad libitum.
1 Nutrient composition of the different feed ingredients used in formulating the test diets (Trials 1 and 2)
Teneur en éléments nutritifs des différents ingrédients utilisés dans les régimes expérimentaux (essais 1 et 2)
Composición de nutrientes de los distintos ingredientes de los piensos utilizados en la formulación de las dietas de experimentación (Ensayos 1 y 2)
|
|
Feed ingredient |
|
|
||||
|
Dates |
Date pips* |
Date leaves |
Sardines |
Barley |
|||
|
Dry matter (DM) |
84.4 |
89.5 |
90.0 |
87.8 |
88.9 |
91.3 |
92.0 |
|
Crude protein (CP) |
4.0 |
6.9 |
5.6 |
65.0 |
11.5 |
7.6 |
18.5 |
|
Crude fibre (CF) |
5.7 |
20.0 |
33.0 |
- |
5.6 |
39.8 |
4.0 |
|
Ether extract (EE) |
1.6 |
8.5 |
2.0 |
4.0 |
2.6 |
0.9 |
2.0 |
|
Ash |
2.6 |
1.9 |
10.5 |
25.9 |
2.5 |
9.4 |
6.0 |
|
Nitrogen free extract (NFE) |
86.2 |
62.7 |
48.9 |
5.1 |
77.8 |
42.3 |
69.5 |
|
Calcium |
0.2 |
0.14 |
0.7 |
4.3 |
0.1 |
0.2 |
0.7 |
|
Phosphorus |
0.07 |
0.13 |
0.1 |
1.0 |
0.4 |
0.1 |
0.55 |
|
Cell-wall content (NDF) |
21.4 |
67.9 |
73.5 |
- |
29.3 |
74.4 |
28.7 |
|
Acid detergent fibre (ADF) |
29.3 |
52.8 |
54.2 |
- |
6.4 |
46.7 |
6.0 |
|
Permanganate lignin |
7.2 |
5.2 |
8.7 |
- |
1.0 |
7.7 |
1.5 |
|
Cellulose |
21.3 |
47.2 |
32.5 |
- |
5.3 |
35.5 |
6.1 |
|
Hemicellulose |
|
15.1 |
19.3 |
- |
22.9 |
27.7 |
22.7 |
* % weight of pips to the whole date fruit (pip+flesh) = 30:70% (as-is basis).
**Rhodes grass hay was not a component of the test diet per se (Trial 2) but was fed at the rate of 2 kg per group daily with both the test and control diets.
The total digestible nutrients (TDN) in Rhodes grass = 55% and the digestible crude protein (DCP) = 4.8 %.
2 Trial 1: Composition of the experimental diets
Essai 1: Composition des régimes expérimentaux
Ensayo 1: Composición de las dietas experimentales
|
Ingredient |
Diet |
|
|
Date |
Barley |
|
|
(percentage of dry matter)1 |
||
|
Barley |
- |
27.6 |
|
Dates |
29.4 |
- |
|
Rhodes grass hay |
22.9 |
26.9 |
|
Calf rearer |
32.2 |
30.8 |
|
Ground sun-cured sardines |
15.4 |
14.7 |
|
Total |
100 |
100 |
|
Concentrate: roughage ratio (%) |
77:23 |
73:27 |
1 The diets were supplemented with salt-licks containing (in addition to NaCl): Ca. 1.3%: P. 0.23%, Mg, 0.3%, Mn 200 mg kg, Co, 124 mg/kg, 1190 mg/kg Zn, 120 mg kg; Fe, 1690 mg/kg; Se, 10 mg kg; Cu. 400 mg/kg, and vitamin D3, 40000 IU/kg.
3 Trial 1: Proximate analysis of the diets and their nutritive value
Essai 1: Analyse grossière et valeur nutritive des régimes expérimentaux
Ensayo 1: Análisis general de las dietas y de su valor nutritivo
|
|
Diet |
|
|
Date |
Barley |
|
|
(percentage of dry matter)1 |
||
|
Crude protein (CP) |
168.5 |
185.0 |
|
Crude fibre (CF) |
94.1 |
107.0 |
|
Ether extract (EE) |
20.0 |
23.0 |
|
Ash |
82.4 |
85.0 |
|
Nitrogen-free extract (NFE) |
635.0 |
600.0 |
|
Calcium |
8.7 |
8.2 |
|
Phosphorus |
3.4 |
4.3 |
|
Total digestible nutrients (TDN) |
632 |
637 |
1 Percentage of dry matter in the date-based diet was 89.4 and in the barley diet 91.3.
Experimental design. The kids were divided into two groups of ten kids each, with a mean live weight of 17.85 ± 2.64 kg and 17.85 ± 3.14 kg, respectively. The groups were allocated at random, ad libitum, to either a pelleted sardine growing/finishing test diet or a pelleted commercial control ration of 15 percent CP. In addition to the experimental diet, each group received 2 kg of Rhodes grass hay daily. The trial lasted for 70 days; the kids were weighed every two weeks before being fed. The composition of the control and test diets is shown in Table 4.
Experimental diets. In the case of the test diet, the date leaves, manually removed from the lower branches of the date palm before fruit harvesting, were sun-dried at a temperature of 32° to 36°C for 10 to 15 days to a DM content of approximately 90 percent. The date pips, purchased from a local date-processing factory, were washed in tap water and sun-dried to a DM content of approximately 89.5 percent after five days at temperatures of 32° to 36°C. The sardines were purchased from a local market and also sun-cured. After the initial drying process, the sun-dried date leaves and pips, the barley and the sardines were machine-ground to a particle size of 2 to 2.5 mm, then mixed and pelleted.
As in Trial 1, the kids were also allowed free access to salt-lick blocks. The nutrient composition of the ingredients used in the test diet, in addition to the Rhodes grass hay, appears in Table 1. The proximate and cell-wall components of the control and test diets are listed in Table 5.
Feeding and management. The feeding and management were similar to that of the calf trial. The nutritive value of the two diets was determined by a digestibility and nitrogen (N) balance trial, which followed the feeding trial. In this trial, three kids were used for each diet and fed ad libitum. They were selected from among the heaviest, medium and lightest individuals of each trial group. The kids were housed in metabolic stalls, especially designed for urine and faeces collection. They were given one week to adapt to these stalls before undergoing a digestibility and N balance trial.
Prior to the distribution of the day's ration, urine and faeces were collected separately from each animal. The urine samples were acidified and immediately frozen. Nitrogen analysis was performed on each sample at the end of the collection period. The faecal samples were oven-dried each day at 105°C for DM determination and then ground to 1.0-mm particles using a cyclotec mill. Approximately 50 g of dried faecal material from each animal was collected daily for chemical analysis. Proximate analyses of both diets and faeces were carried out according to AOAC methods (AOAC, 1984). Nitrogen in the urine was determined by the Kjeldahl method also using AOAC standards (AOAC, 1984), while the cell-wall constituent analyses for both the diets and faecal samples were done according to Goering and Van Soest (1970).
Statistical analysis. In both trials, the differences in the growth performance of calves (Trial 1) and goats (Trial 2) were tested for significance by the Students' l-test, according to Steel and Torrie (1960).
Trial 1: Dates and sardines for growing calves
The chemical composition of the different ingredients used in the two diets indicates that sardines are an excellent source of protein (65 percent CP) and minerals, particularly calcium (Ca) and phosphorus (P). In addition, dates are rich in carbohydrates and nitrogen-free extract (NFE), compared with barley, which is relatively higher in protein and phosphorus.
The calves consumed similar total quantities of both diets. However, the consumption of dates was relatively higher than that of barley. The calves fed on the barley-based diet consumed more Rhodes grass hay than the calves fed on the date-based diet. The data with respect to performance are given in Table 6. The daily DM intake was higher for calves fed on the date-based diet (3008 g vs. 2778 g). The DM intake was also higher in the date-based diet when expressed either as a percentage of body weight (W) or on the basis of metabolic body weight (W0.75), which indicates that the date-based diet was more palatable than the barley diet.
Feed conversion and average daily gain were better for the calves on the date-based diet. However, the difference in average daily gain was not statistically significant (P>0.05). In general, feed conversion and growth rates were good for both diets. Feeding costs are summarized in Table 7. It was evident that by using dates as feed, the cost was decreased by 8.4 percent, expressed in rial Omani (RO/kg live-weight gain).
Trial 2: Evaluation of date by-products and sardines for growing goats
The nutrient composition of both date leaves and pips seemed to be similar or even better than that of Rhodes grass hay, as evidenced by their lower contents of crude fibre and higher contents of NFE, ether extract (EE), Ca and P (Table 1). Likewise, it can be seen that the CP content of Rhodes grass hay is higher than that of either date leaves or pips. Sardines are an excellent source of CP (65 percent) and minerals (25.9 percent), particularly Ca (4.3 percent) and P (1 percent). Barley is rich in carbohydrates and NFE (77.8 percent) and a moderate source of CP (11.5 percent).
The diets were almost isonitrogenous; however, the crude fibre fraction was slightly higher in the experimental sardine diet compared with that of the control diet. The content of ash was somewhat similar in both diets, particularly with regard to Ca and P. The experimental diet was slightly lignified compared with the control diet. Therefore, the relatively high content of permanganate lignin (8.7 percent) was to be expected and was no doubt a result of the high content of date byproducts, particularly the date leaves (Table 1).
4 Trial 2: Formulation of experimental diets
Essai 2: Formulation de régimes expérimentaux
Ensayo 2: Formulación de las dietas experimentales
|
|
Diet |
|
|
Test (date by-products) |
Control |
|
|
(percentage - as-fed basis)1 |
||
|
Date pips |
20 |
- |
|
Date leaves |
20 |
- |
|
Sardines |
10 |
- |
|
Barley |
495 |
344 |
|
Maize grain |
- |
20.35 |
|
Ground oats |
- |
14.0 |
|
Rice bran |
- |
15.0 |
|
Soybean meal |
- |
11.95 |
|
Common salt |
0.5 |
0.435 |
|
Limestone |
- |
2.585 |
|
Sodium bicarbonate |
- |
0.3 |
|
Dicalcium phosphate |
- |
0.57 |
|
Vitamins and trace |
- |
0.41 |
|
Mineral pre mix |
- |
- |
|
Total |
100 |
100 |
1 Animals on both diets were allowed free access to salt-licks containing (in addition to NaCl): Ca, 1.3%; P. 0.23%; Mg, 0.3%; Mn, 200 mg/kg; Co, 124 mg/kg; I, 190 mg/kg; Zn, 120 mg/kg; Fe, 1690 mg/kg; Se, 10 mg/kg; Cu. 400 mg/kg; and vitamin D3, 40000 IU/kg.
5 Trial 2: Proximate and cell-wall constituents of the diets
Essai 2: Eléments grossiers et de parois cellulaires des régimes
Ensayo 2: Componentes generales y componentes de la pared celular en las dietas
|
|
Diet |
|
|
Test (date by-products/sardines) |
Control |
|
|
(percentage of dry matter) |
||
|
Dry matter (DM) |
90.3 |
89.6 |
|
Crude protein (CP) |
15.6 |
16.0 |
|
Crude fibre (CF) |
12.0 |
8.0 |
|
Ether extract (EE) |
3.5 |
2.0 |
|
Ash |
7.4 |
9.8 |
|
Nitrogen-free extract (NFE) |
61.5 |
64.2 |
|
Calcium |
0.8 |
0.9 |
|
Phosphorus |
0.56 |
0.55 |
|
Cell-wall content (NDF) |
48.9 |
41.0 |
|
Acid detergent fibre (ADF) |
26.7 |
7.9 |
|
Permanganate lignin |
8.6 |
2.7 |
|
Cellulose |
15.6 |
7.8 |
|
Hemicellulose |
22.2 |
33.1 |
6 Trial 1: Performance of the calves during the experimental period
Essai 1: Productivité des veaux pendant la période expérimentale
Ensayo 1: Resultados obtenidos en los terneros durante el periodo experimental
|
|
Diet |
||
|
Dates |
Barley |
SE |
|
|
Period (days) |
98 |
98 |
- |
|
Initial live weight (kg) |
71.61 |
71.4 |
5.5 NS |
|
Final live weight (kg) |
131 |
118 |
9.6 NS |
|
Live-weight gain (g/day) |
606 |
476 |
56.5 NS |
|
DM intake (g/day) |
3008 |
2777.6 |
|
|
DM intake (% body weight) |
2.97 |
2.9 |
|
|
DM intake (g/kg W0.75) |
94.2 |
91.5 |
|
|
Feed efficiency |
4.96 |
5.84 |
|
SE = standard error.
DM = dry matter.
NS = not significant (P>0.05).
Table 8 presents the mean apparent digestibility coefficients, in percent, for DM, organic matter (OM), CP, crude fibre (CF), EE, NFE and cell-wall constituents, in addition to N balance, energy [total digestible nutrients (TDN) and metabolizable energy (ME)] and digestible crude protein (pop) of the diets. The mean apparent digestibility, in percent, was significantly higher (P<0.01) for CF and cell-wall constituents: NDF, cellulose and lignin for the sardine-based experimental diet. Hemicellulose digestibility was also higher for the test diet, but not significantly different (P>0.05) from that of the control diet. However, the control diet had significantly higher digestibility of CP (P<0.01) and NFE (P<0.05) than the test diet. The mean apparent digestibility for DM, OM and EE, in percent, for both diets was not significantly different (P>0.05). However, the control diet had slightly higher values for both OM and DM digestibilities compared with the EE digestibility, which was slightly higher for the test diet.
Nitrogen balance was only slightly different for both diets (P>0.05). Energy, expressed both as percent TDN or ME (MJ/kg DM), was slightly higher for the test diet. However, pop (g/kg DM) was relatively higher for the control diet.
Table 9 summarizes feedlot performance of kids on both diets. Kids fed on the sardine-based test diet gained significantly (P<0.01) more weight (172 g/day) than those fed on the control diet (128 g/day). The DM intake (g/day) was also higher for kids fed on the test diet (868 g/day) compared with kids fed on the control diet (758 g/day). The DM intake was higher as well for the test diet when it was expressed either as a percentage of body weight or on the basis of metabolic body weight (W0.75), reflecting more palatability for the sardine-based test diet than for the control diet. This was particularly true since the kids on the test diet consumed less Rhodes grass hay (71 g of Rhodes grass hay + 797 g of the experimental diet/day) compared with those fed on the control diet (108 g of Rhodes grass hay + 650 of the control diet/day). The percentage ratio of concentrate to roughage was 92:8 for the test diet and 86:14 for the control diet.
It is worth mentioning that animals on the test diet did not show any signs of diarrhoea or other ill effects, even though they consumed more of the test diet, unlike the animals on the control diet, which suffered from occasional diarrhoea particularly after consuming much of the control diet. Faeces of kids on the control diet were relatively softer and had less DM content than those on the test diet. It was obvious that the kids fed on the test diet could manage without any additional forages, while kids on the control (commercial concentrate) diet needed additional forages as this diet was relatively low in CF content.
Energy intake (TDN or ME) and pop was higher for kids fed on the test diet. Although the kids on both diets showed excellent feed conversion, those on the test diet performed better (5 g DM/g gain).
Trial 1: Dates and sardines for calves
The results showed that the performance of calves fed on the date-based diet was superior to that of the calves fed on the barley-based diet. This was expected since dates, being a good source of readily available energy, fed together with sardines provided more favourable conditions for microbial synthesis. Shahna, Qassim and Al-Qahri (1987) analysed 20 types of dates in Yemen and reported that they contain a high proportion of reducing sugars, ranging from 61.1 to 90.8 percent, while the major carbohydrates in barley are predominantly starches. It is possible that the sugars in dates were more readily available to the rumen microbes than the carbohydrates in barley. The fact that the date-based diet was more palatable than the barley-based diet is also supported by the reported higher palatability of molasses diets.
Commercial fish-meals are known to be a good source of protein (about 65 percent CP) and an excellent source of the essential amino acids: lysine, methionine and tryptophan. The digestibility of fish protein ranges between 93 and 95 percent. In addition to a high biological value, the mineral content of fish-meals is about 21 percent. As well as containing a high proportion of Ca (8 percent) and P (3.5 percent), there are also other trace minerals including manganese, iron and iodine. Fish-meal is also a good source of B-complex vitamins, particularly choline, B12 and riboflavin. Because of the high quality of protein in fish-meal and a growth factor known as the Animal Protein Factor, it is generally used for monogastric animals and young ruminants (McDonald, Edwards and Greenhalgh, 1981).
The nutrient composition of the sun-cured sardines used in this study was similar to the values provided by McDonald, Edwards and Greenhalgh (1981). However, the sun-cured sardines were slightly higher in total ash content (25.4 percent), but lower in both Ca (4.3 percent) and P (1.04 percent). The high total ash content in sardines in the Sultanate of Oman may be a result of their having been spread on sandy shores to sun-dry. This might have resulted in silica contamination, thus contributing to a higher ash content. It has been suggested that some type of refinement be introduced in this traditional drying method. It is worth mentioning that the protein quality (digestibility and biological value) of the sardines used in this study was expected to be very high since they were not exposed to very high drying temperatures as some commercial fish-meals are. In this study, no ill effects were observed in the calves fed the diets containing sun-dried sardines.
The Sultanate of Oman produces both sardines and dates. They are readily available and if used in the quantities stated in this study (a diet of 15 percent DM of sardines and about 33 percent air-dried dates), an appreciable growth performance could be achieved, while reducing feeding costs by 8 percent.
7 Trial 1: Cost of feeding for the two diets1
Essai 1: Coût des deux régimes expérimentaux
Ensayo 1: Costo de los alimentos correspondientes a ambas dietas
|
|
Diet |
|
|
Dates |
Barley |
|
|
Cost of feeding/head/day2 |
0.257 |
0.220 |
|
Cost of feeding per kg of diet |
0.074 |
0.072 |
|
Cost of feeding during the test period (98 days) |
25.200 |
21.600 |
|
Total live-weight gain during the experiment (kg) |
59.400 |
46.600 |
|
Cost per kg live-weight gain |
0.424 |
0.463 |
1 The costs were calculated by using individual costs of the ingredients as consumed in the diets.
2 Costs are in rial Omani.
8 Trial 2: Mean apparent digestibility coefficients, nitrogen balance and nutritive value of the diets
Essai 2: Coefficients moyens de digestibilité apparente, bilan azoté et valeur nutritive des régimes
Ensayo 2: Coeficientes medios de digestibilidad aparente, balance de nitrógeno y valor nutritivo de las dietas
|
|
Diet |
||
|
Test (date by-products/sardines) |
Control |
SE |
|
|
Apparent digestibility coefficients (%) |
|
||
|
Dry matter (DM) |
73.5 |
75.6 |
0.83 NS |
|
Organic matter (OM) |
76.0 |
79.0 |
1.4 NS |
|
Crude protein (CP) |
71.7 |
83.3 |
1.56** |
|
Crude fibre (CF) |
53.0 |
25.04.0** |
|
|
Ether extract (EE) |
87.6 |
86.3 |
1.0 NS |
|
Nitrogen-free extract (NFE) |
81.3 |
84.6 |
0.75* |
|
Cell-wall content (NDF) |
72.7 |
58.5 |
3.0** |
|
Cellulose |
59.3 |
29.0 |
4.4** |
|
Hemicellulose |
95.3 |
79.7 |
11.0 NS |
|
Lignin |
49.0 |
12.0 |
5.5** |
|
Nitrogen balance |
|
||
|
N intake (g/day) |
19.8 + 1.8 |
17.6 + 2.7 |
|
|
Faecal N (g/day) |
5.7 + 1.0 |
2.6 + 0.45 |
- |
|
Urinary N (g/day) |
4.1 + 2.0 |
5.8 + 2.1 |
- |
|
N retention (g/day) |
10.0 |
9.2 |
0.6 NS |
|
Nutritive value |
|
||
|
Total digestible nutrients (TDN) (%) |
74.4 |
73.5 |
|
|
Metabolizable energy (ME) (MJ/kg DM) |
11.26 |
11.12 |
|
|
Digestible crude protein (DCP) (g/kg DM) |
111.85 |
133.3 |
|
ME was calculated from TDN: 1 kg TDN = 3.6155 Mcal ME = 15.13 MJ of ME.
SE = standard error.
NS = not significant.
* significant difference (P<0.05).
** significant (P<0.01).
9 Trial 2: Feedlot performance of kids during the experimental period
Essai 2: Performances de jeunes animaux en pares d'embouche pendant la période expérimentale
Ensayo 2: Resultados experimentales de engorde en corral de cabritos
|
|
Diet |
||
|
Test (date by-products/sardines) |
Control |
SE |
|
|
Period (day) |
70 |
70 |
- |
|
Initial live weight (kg) |
17.85 |
17.85 |
0.9 NS |
|
Final live weight (kg) |
29.9 |
26.8 |
1.45 NS |
|
Live-weight gain (g/day) |
172 |
128 |
9.8** |
|
Dry matter (DM) intake1 (g/day) |
868 |
758 |
- |
|
DM intake (% body weight) |
3.63 |
3.4 |
|
|
DM intake (g/kg W0.75) |
80.4 |
73.8 |
|
|
Digestible crude protein (DCP) intake (g/day) |
92.5 |
91.9 |
|
|
Total digestible nutrients (TDN) intake (g/day) |
631.84 |
537.4 |
|
|
Metabolizable energy (ME) intake (MJ/day) |
9.56 |
8.13 |
|
|
DM/gain (g/g) (feed conversion) |
5 |
5.9 |
|
SE = standard error.
NS = not significant.
1 The mean DM intake (g/day) included Rhodes grass hay. The DM intake for the (DBP-sardine) test diet only was = 797 + 71 g Rhodes grass hay/day. The concentrate-to-roughage ratio was 92:8.
DM intake for the control diet was 650 g + 108 g/day for the Rhodes grass hay. The concentrate-to-roughage ratio was 86:14.
Trial 2: Evaluation of date by-products and sardines for growing goats
Sardines and date by-products are two locally available and relatively cheap protein/mineral supplements that could be used in formulating livestock rations. A laboratory analysis (Table 1) has indicated that the nutrient composition of date by-products is superior to that of Rhodes grass hay, except for its relatively low CP content.
The results obtained in this study have clearly demonstrated the potential of date by-products when supplemented with sardines as a substitute for the conventional roughage component in pelleted growing/finishing ruminant diets in the sultanate. This was supported by a higher average daily gain, a 14.4 percent higher intake of DM and a superior feed conversion.
The digestibility of the crude fibre fraction [CF, cell-wall content (NDF), cellulose and hemicellulose] was substantially improved in the test diet. Riewe and Lippke (1969) had reported that a 1 -percent increase in intake per 100 kg of body weight lowered the apparent digestibility of DM by 1 to 6.5 percent, depending on the quality of the forage. The decrease in DM digestibility of the test diet observed in this study was in agreement with their findings. Similarly, decreases in the digestibility of OM, CP and NFE of the test diet could be explained by the increase in the intakes of those fractions.
Fish-meal was reported to have an enhanced nutritional value because of its growth factor content, known collectively as the Animal Protein Factor (McDonald, Edwards and Greenhalgh, 1981). Nitrogen supplementation of low-quality roughage was reported to have a stimulating effect on the cellulytic microflora of the rumen with a resultant increase in the rate of passage of feed particles along the intestinal tract (sampling, Freer and Balch, 1962; Campling and Murdoch, 1966). The improvement in DM intake and digestibility of the crude fibre fraction observed in this study for the test diet was also in agreement with these findings.
The apparent partial degradation of lignin observed in this study was likely to be an artefact of differential analytical characteristics of feed versus faecal "lignin". The results obtained in this study for lignin degradation were in agreement with the results obtained by Brown and Johnson (1985) for wheat straw diets using goats and sheep.
Date leaves used in this study were obtained without cost since they were not yet known as marketable animal feed in the sultanate, and the price charged for date pips was nominal. Sardines, a potential protein supplement, are available locally at a relatively low cost. The sardine-based experimental diet was expected to cost at least-30 percent less than the control (commercial concentrate) diet. Furthermore, the improved feed conversion, coupled with the excellent growth rate obtained with the test diet, substantially reduced the costs for kids fed on the sardine-based experimental diet.
The data obtained in this study add to previously published data, showing that many local by-products have economic potential for use in ruminant diets in the Sultanate of Oman.
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