The use of cassava feeding rabbits

Cassava root meal
Cassava peel meal
Cassava leaf meal
Effect of processing on feeding value of cassava
References

T.A. Omole

Rabbits could be fed on 30% cassava root meal in their diets without adverse effects on body growth and organ measurements. Higher levels of dietary cassava should be carefully used to avoid the effects of harmful substances in the diet. Supplementation with 0.2% methionine or 2% palm oil is desirable in diets containing up to 4% cassava root meal. The reproductive ability of the rabbit is not impaired by the use of cassava root meal as long as other essential nutrients are supplied in the diet. The cassava peel will require a conscious supplementation of both methionine and dietary fat. About 5% palm oil will be useful for dietary cassava peel beyond the 30% level in the ration. Levels higher than 45% for both cassava mot meal and cassava peel should be investigated under varying dietary conditions. Also, there Is the need to explore the potential of cassava leaf meal and the various processing conditions that may affect the utilization of cassava root and by-products by rabbits.

The rabbit industry is growing in many countries in Africa today, hence feeding problems associated with poultry and pig farming are now being encountered by rabbit breeders who depend solely on pellets and concentrates for their animals. For backyard rabbit raising, which is widely practiced in most parts of Africa, feeding of green herbage is advantageous, since greens are available all year round in the coastal regions and low plains of the continent. If palatable greens are fed free choice, the amount of pelleted feed needed can be reduced by about 50 percent, with no adverse effects on performance (Cheek et al. 1987). Since most greens have a very high water content, large amounts have to be consumed to meet the nutritional requirements of the rabbit. Because they are noiseless, rabbits can be raised in garages and servants' quarters in urban centres without infringing on the peace of the neighbors. Very little space is usually needed. Cheek et al. ( 1987) described rabbit meat as a wholesome tasty product. Compared with most other meets, such as beef, chicken, lamb and pork it is high in protein and low in fat, cholesterol, and sodium. The meat is white, fine-grained, delicately flavored, nutritious, and appetizing (USDA 1963).

The new impetus for rabbit production in Africa amongst a wide range of people creates the need for alternative cheap sources of rabbit feed to replace or supplement cereals in rabbit pellets in order to make rabbit production profitable.

Results by Eshiet et al. ( 1979) indicate that energy supply in the rabbit diet is critical for maximum utilization of nutrients. Cassava is one of the most productive tropical crops in terms of its energy yield-13 times more per hectare than for maize guinea corn (Oyenuga 1961). The cassava root has an estimated average composition of 60-65 % moisture, 30-35 % carbohydrate, 0.2-0.6 % ether extract, 1-2 % crude protein. It has relatively low content of minerals and vitamins, although it is fairly rich in calcium and ascorbic acid and contains nutritionally significant amounts of thiamine, riboflavin and niacin. However, cassava contains undesirable compounds such as hydrocyanic acid (HCN) released through acid or enzyme hydrolysis of the cyanogenic glucosides, linamarin and lotaustralin, which could make its value as animal feed doubtful.. This paper describes experiments in utilization of cassava for feeding rabbits.

Cassava root meal

Growth: Eshiet et al. (1979) fed 0, 15, 30 and 45 % cassava root meal, in isocaloric and isonitrogenous diets, to fryer rabbits. They observed that rabbits could tolerate up to 30% cassava root meal diet without adverse effects on feed intake and rate of growth. The 45 % cassava root level, however, gave poor growth and utilization efficiency. None of the cassava root meal levels influenced the carcass parameters and thiocyanate levels of urine and serum in the rabbits (tables 1 and 2).

Table 1. The effect of feeding graded levels of cassava root meal on the live performance of fryer rabbits

Parameter	Level of CRMa (%)
	0	15	30	45
Rate of gain (g/rabbit/day)	18.25	18.53	18.52	16.72
Feed intake (g/rabbit/day)	24.02c	56.43a	60.54ab	79.92b
Feed/gain	2.63a	3.05b	3.26b	4.78c
Mortality (%)	25.00	12.50	12.50	25.00 .

Source: Eshiet et al. (1979)
Notes: ^a CRM = cassava root meal
Row means bearing different letters are significantly different (P<0.05)

In an attempt to make diets isocaloric the level of palm oil supplementation of the diets was decreased as the cassava root meal was increased to the extent that, while the control diet contained 2.5% palm oil, the 45% cassava root meal diet contained no added fat. This situation made it difficult to establish that 45% cassava root meal may not support a good growth rate for fryer rabbits, since the addition of fat to rabbit diet improves feed utilization (Raimondi et al. 1973). Cassava root meal is also deficient in essential fatty acids. Hudson and Ogunsua (1974) reported that fat in cassava tuberous roots contains 1.46% linoleic acid, which is low compared to the 60.8% in maize (Hilditch and Williams 1974). Omole (1977) indicated that under practical conditions, linoleic acid may be submarginal in cassava root meal diets containing low levels of yellow maize and no added fat. When diets were slightly modified by the addition of 20% palm oil to each diet, and 200g each of green herbage (Aspilia africana) was offered every other day, the performance of rabbits fed on 45% cassava root meal was as good as those on the control diet.

Table 2. Effect of cassava root meal on carcass characteristics and serum and urine thiocyanate concentrations of fryer rabbits

Parameter	Level of CRMa (%)
	0	15	30	45
Carcass yield (g/ 100g live weight)	47.35	50.30	48.14	47.63
Skin (g/ 100g live weight)	10.03	11.18	9.75	9.00
Kidney (g/ 100g live weight)	0.56	0.64	0.55	0.53
Liver (g/ 100g live weight)	3.27	3.13	2.90	2.64
Intestine (g/cm)	0.15	0.17	0.15	0.18
Caecum (g/cm)	0.30	0.29	0.26	0.23
Serum thiocyanate (mg/ 100ml)	1.59	1.72	1.66	1.76
Urine thiocyanate (mg/100ml)	2.94	3.15	3.15	3.21

Source: Eshiet et al. (1979)
Note: ^a CRM = cassava root meal

Reproduction: Studies at the Obafemi Awolowo University in Nigeria showed that pregnant and lactating does could be fed with up to 45% dietary cassava root meal without any significant effect on litter size, birth weight of pups, and weaning weight of offspring (tables 3, 4, 5, 6 and 7).

Table 3. The effect of cassava root meal on the reproductive performance of rabbits at first breeding

Parameter		Level of CRMa (%)
		0	15	30	45
Initial live weight of does (kg)		1.89	2.01	1.98	2.02
Prebreeding feed intake (g/rabbit/day)		92.93	92.10	93.31	98.05
Feed intake during gestation (g/rabbit/day)		107.74	113.66	111.28	124.17
Gestation length (days)		31.00	30.67	31.25	31.06
Number of pups per litter at:
	Birth	5.00	6.26	6.00	6.00
	Weaning	3.00	5.00	4.20	5.67
Weaning weight (kg)		0.52	0.38	0.48	0.36

Source: Eshiet et al. (1980)
Note: ^a CRM = cassava root meal

The lactating dams grew normally on cassava root meal diets. The study covered three breeding periods which recorded striking similarities in reproductive performance between treatments suggesting that cassava root meal diets fed before breeding and during gestation had no adverse effects on the reproductive capacity of the does.

There has been some speculations about the possibility of intraplacental transfer of cyanide or its metabolic product, thiocyanate, from the maternal blood to the embryo. It has, however, been reported that in spite of the constant communication with the dam, the rat embryo appears to be protected from the toxic influences of cyanide or its biotransformation product, thiocyanate (Tewe 1975). Cassava root meal at 4% does not seem to adversely alter the urine and serum thiocyanate levels.

Table 4. Effect of graded levels of cassava root meal on the reproductive performance of rabbits at second breeding

Parameter		Level of CRMa (%)
		0	15	30	45
Number of pups per litter at:
	Birth	6.67	5.67	6.67	5.67
	14 days post partum	6.67	5.33	4.67	4.00
	28 days post partum	5.00	4.67	4.00	4.00
	Weaning	5.00	4.67	4.00	4.00
Live weight of pups at:
	14 days of age (kg)	0.14	0.15	0.15	0.15
	28 days of age (kg)	0.35	0.37	0.34	0.40
	Weaning (kg)	0.51	0.53	0.50	0.55

Source: Eshiet, Ademosun and Omole (198:0)
Note: ^a CRM = cassava mot meal

Table 5. Effect of graded levels of cassava root meal on the reproductive performance of rabbits at third breeding

Parameter		Level of CRMa (%)
		0	15	30	45
Number of pups per litter at:
Birth		6.00	6.00	6.00	6.00
	14 days post partum	4.50	5.50	4.50	4.75
	28 days post partum	4.00	4.00	4.00	4.00
	Weaning	3.50	4.00	4.00	4.00
Live weight of pups at:
	14 days of age (kg)	0.19	0.17	0.18	0.19
	28 days of age (kg)	0.37	0.35	0.37	0.36
	Weaning (kg)	0.49	0.46	0.50	0.46
Serum thiocyanate (mg/ 100 ml)		1.20	1.26	1.36	1.14
Urine thiocyanate (mg/ 100 ml)		2.44	2.55	2.35	2.96

Source: Eshiet et al. (1980)
Note: ^a CRM = cassava root meal

Table 6. Effect of cassava root meal on fryer rabbits whose dams have also been on same diets

Parameter	Level of CRMa (%)
	0	15	30	45
Initial live weight at 5 weeks (kg)	0.48	0.47	0.53	0.46
Final live weight at 13 weeks (kg)	1.46	1.38	1.49	1.37
Rate of weight gain (g/rabbit/day)	17.05	16.23	17.01	16.35
Feed intake (g/rabbit/day)	49.28	47.41	49.51	47.96
Feed/gain	2.89	2.93	2.91	2.94
Mortality (%)	0.00	0.00	0.00	0.00

Source: Eshiet et al. (1980)
Note: ^a CRM = Cassava root meal

Table 7. Effect of graded levels of cassava root meal on carcass characteristics, serum and urine thiocyanate of fryer rabbits whose dams have also been on same diets

Parameter	Level of CRMa (%)
	0	15	30	45
Carcass yield (g/100g live weight)	46.86	48.07	49.02	51.55
Skin (g/100g live weight)	9.75	8.80	10.43	9.55
Kidney (g/100g live weight)	0.93	1.01	0.87	0.87
Liver (g/ 100g live weight)	2.88	2.95	2.98	3.03
Heart (g/100g live weight)	0.42	0.39	0.36	0.37
Pancreas (g/ 100g live weight)	0.21	0.24	0.20	0.21
Visceral fat (g/ 100g live weight)	0.60	0.53	0.86	0.67
Length of intestine (m)	2.80	2.20	2.47	2.58
Length of caecum (cm)	33.25	28.50	33.25	31.25
Serum thiocyanate (mg/100ml)	1.31	1.25	1.44	1.39
Urine thiocyanate (mg/100ml)	2.83	3.08	3.21	3.15

Source: Eshiet et al. ( 1980)
Note: ^a CRM = Cassava root meal

Cassava peel meal

Cassava peel contains 27.9% dry matter, 5.3% crude protein and 1.2% ether extract. It is relatively high in crude fiber (20.97%), and ash (5.93%). It contains 66.6% nitrogen free extract. However, it has a higher HCN content than the pulp.

Omole and Sonaiya (1981) evaluated the utilization of cassava peel meal by rabbits in two separate studies. Rabbits were fed graded levels of up to 40% cassava peel meal with either fishmeal or groundnut cake as the sole supplementation, or these same diets combined with 0.2% methionine supplementation. Cassava peel meal could make up to 40% of the ration of fryer rabbits without any deleterious effects on live performance, especially when fishmeal was used. Significant differences in feed values were associated with protein source rather than with the incorporation of cassava peel meal in the diet, at least to the 40% level, since the fishmeal diets were consistently superior to groundnut cake diets at all levels of cassava peel meal (tables 8 and 9). It appeared that the utilization of cassava peel meal by rabbits was limited by the balance of essential nutrients, especially sulfur acids in the diets. Job (1975) reported that methionine or elemental sulfur supplementation significantly improved the efficiency of protein utilization in pigs fed with cassava diets.

The crude fiber content of cassava peel could have significant effects when up to 40%, of cassava peel meal is incorporated in the diet. For example, Omole and Onwudike (1981) reported growth depression in rabbits fed diets containing more than 10% crude fiber.

Although the HCN content of cassava peel is higher than that of the root, feeding relatively high levels of cassava peel does not seem to cause any problems of hydrocyanic toxicity, especially when the diet is supplemented with methionine. Serum and urine thiocyanate level of rabbits were not influenced when cassava peel meals were supplemented by methionine, as suggested by the results of Job (1975) on pigs. Maner and Gomez (1973) had noted an increase in urinary thiocyanate level of rats fed on methionine supplemented, cassava-based diets. It seems that supply of sulfur for HCN detoxification of cassava-based diets could take place only after the sulfur-amino acid deficiency in the diet had been taken care of.

Omole and Onwudike (1982) investigated the effects of palm oil in cassava peel diets for rabbits. In one experiment, they fed 0, 10,20,30, 40, and 50 % dietary cassava peel meal without dietary palm oil while in another, they included 5% palm oil with the same level of cassava peel meal. It was observed that dietary palm oil improved live performance in all the treatments, including the control that did not contain any cassava peel meal. In both studies, inclusion of up to 30% cassava peel meal seemed to cause no significant depression in growth or feed utilization (tables 10 and 11).

With palm oil supplementation however, judging from the serum thiocyanate level, the inclusion of cassava peel meal could be as high as 50%. Hutagalung (1977) attributed improved performance with feeding palm oil in cassava-based diets to increased energy intake by the animals. Recent reports, however, indicate that palm oil may play some additional role beyond increasing energy intake. Fomunyan et al. (1981) showed that the rate of hydrolysis of the cyanogenic glucosides in cassava to produce the poisonous hydrogen cyanide was greatly reduced with palm oil. They therefore suggested that in animals fed cassava-based diets, supplemented with palm oil, delay in HCN decomposition may prevent absorption of the cyanogenic glucosides.

Cassava leaf meal

There is very little information on the feeding values of cassava leaf for the rabbit. However, cassava leaf has been used for feeding calves in France (Guin and Andovard 1910), and cattle in Cuba (Osvaldo 1976) and in Madagascar (Seeres 1969). It is considered to be a valuable forage in Brazil, especially during the dry season when most other crops are scarce (Gramacho 1973). Omole (1977) observed that cassava leaf is a good source of protein, fiber, minerals and vitamins. It contains approximately 25.8 to 27.3 % crude protein, 7.6 to 10.5% fat, 5.7 to 8.8% ash, 4.8 to 7.9 % crude fiber and 50.1 to 51.9 % nitrogen free extract, on dry matter basis. The lysine content is considerably high (6.33 to 7.20% of crude protein), but methionine, and probably tryptophan, are deficient (Rogers and Milner 1963). Devendra ( 1977) observed that the sulfur containing amino acids, cystine and methionine, are low in relation to the others (table 12).

Table 8. Effect of unsupplemented cassava peel meal and protein sources In live performance, carcass measurements, serum and urine thiocyanate levels of growing rabbits

Cassava peel meal (%)	0%		20%		40%
Protein sourcea	FM	GNC	FM	GNC	FM	GNC	±SEM
Average initial weight (g)	575.6	578.2	580.2	584.7	579.4	582.1	nd
Average final weight (g)	1994.2	1659.7	1936.5	1635.5	1840.5	1453.5	nd
Daily feed intake (g)	76.27b	70.68b	77.26b	71.66b	77.47b	63.02a	3.72
Daily gain (g)	25.34c	19.31ab	24.22c	18.76ab	22.52bc	15.56a	1.97
Feed (g)/gain (g)	3.01a	4.66abc	3.19ab	3.82abc	3.44abc	4.05c	0.34
Liver (% body weight)	2.82	2.63	2.76	2.47	2.54	2.29	0.29
Kidney (% body weighs)	0.64	0.55	0.64	0.53	0.59	0.49	0.08
Kidney fat (% body weight)	0.50	0.48	0.59	0.60	0.64	0.66	0.09
Carcass yield (%)	55.45	57.71	56.26	59.63	57.23	59.84	2.74
Serum thiocyanate (mg/100 ml)	1.60a	1.59a	1.76ab	1.78ab	1.79ab	1.82b	0.10
Urine thiocyanate (mg/100 ml)	2.95a	2.97a	3.41b	3.33b	3.82b	3.64b	0.21

Source: Omole and Sonaiya (1981)
Notes: ^a Protein source FM = fishmeal, GNC = groundnut cake
Values in each row with different letters are significantly different (P<0.05)
nd = not determined

Table 9. Effect of methionine supplementation on live performance, carcass measurements, and serum and urine thiocyanate levels of rabbits fed cassava peel meal with proteins

Cassava peel meal (%)	0%		20%		40%
Protein sourcea	FM	GNC	FM	GNC	FM	GNC	±SEM
DL Methionine (%)	0.2	0.2	0.2	0.2	0.2	0.2
Average initial weight (g)	737.8	741.2	742.4	739.5	738.3	745.2	nd
Average final weight (g)	2188.8	1982.2	2155.8	1948.0	2033.6	1717.9	nd
Daily feed intake (g)	77.99b	75.79b	79 51b	81.9b	77.95b	68.79a	3.98
Daily gain (g)	25.91c	22.16bc	25.24bc	21.58b	23.13bc	17.37a	2.07
Feed(g)/gain (g)	3.01a	3.42ab	3.15a	3.79bc	3.7ab	3.96c	0.26
Liver (% body weight)	3.01	2.85	2.97	2.76	2.88	2.69	0.20
Kidney (% body weighs)	0.64	0.61	0.64	0.58	0.61	0.53	0.06
Kidney fat (% body weight)	0.42a	0.45a	0.68b	0.62b	0.71b	0.68b	0.07
Carcass yield (%)	54 73	55.18	55.74	56.51	56.37	57.14	2.01
Serum thiocyanate (mg/100 ml)	1.58	1.58	1.67	1.71	1.75	1.77	0.11
Urine thiocyanate (mg/100 ml)	2.94a	2.93a	3.23ab	3.18ab	3.45b	3.39ab	0.24

Source: Omole and Sonaiya (1981)
Notes: ^a Protein source FM = fishmeal, GNC = groundnut cake
Values in each row with different letters are significantly different (P<0.05)
nd = not determined

Table 10. Effect of different levels of cassava meal and supplementary palm oil on live and carcass measurements of growing rabbits

Performance characteristic	Level of cassava peel meal (%)						SE (mean), Level of significancea
	0	10	20	30	40	50
Average initial weight (g)	617.5	615.8	620.1	622.4	624.5	621.7	nd
Average final weight (g)	1942.5	1969.3	1955.7	1933.9	1663.9	1470.7	nd
Daily feed intake (g)	73.11a	75.17a	72.50a	75.18a	71.84a	69.63a	3.04NS
Daily gain (g)	23.66c	24.17c	23.85c	23.42c	18.56b	15.16a	1.69
Feed(g)/gain (g)	3.09a	3.11a	3.04a	3.21a	3.87b	4.59c	0.31
Liver (% body weight)	3.27a	2.83a	3.01a	2.95a	3.05a	3.07a	0.19NS
Kidney (% body weight)	0.52a	0.53a	0.57a	0.55a	0.49a	0.51a	0.05NS
Carcass yield (%)	56.53a	57.77a	57.86a	58.45a	59.17a	55.64a	1.98NS
Serum thiocyanate (mg/100 ml)	1.56a	1.58a	1.57a	1.54a	1.57a	1.53a	0.05NS
Urine thiocyanate (mg/100 ml)	2.87a	2.98a	3.15ab	3.19ab	3.57ab	3.46ab	0.22

Source: Omole and Onwudike (1982)
Notes: Means within a row not followed by the same letter differ significantly
^a NS = no significant difference at (P<0.05)
nd = not determined

Table 11. Effect of different levels of cassava peel meal on live carcass and organ measurements of growing rabbits

Performance characteristic	Level of cassava peel meal (%)						SE (mean), Level of significance a
	0	10	20	30	40	50
Average initial weight (g)	963.7	958.4	956.5	965.5	959.0	968.0	nd
Average final weight (g)	2179.5	2238.0	2208.7	2079.9	1880.2	1611.2	nd
Daily feed intake (g)	70.56ab	72.89b	70.21ab	70.84ab	68.60ab	65.71a	3.53
Daily pain(g)	21.71c	22.85c	22.36c	19.90c	16.45b	11.65a	1.71
Feed(g)/gain (g)	3.25a	3.19a	3.14a	3.56a	4.17b	5.64c	0.30
Liver (% body weight)	2.95a	2.88a	3.01a	2.93a	2.98a	2.75a	0.18NS
Kidney (% body weighs)	0.55a	0.56a	0.61a	0.59a	0.60a	0.60a	0.04NS
Kidney fat (% body weight)	0.39a	0.47ab	0.51ab	0.54ab	0.54ab	0.62b	0.09
Carcass yield (%)	57.34a	55.72a	55.49a	56.38a	57.28a	58.66a	1.57NS
Serum thiocyanate (mg/100 ml)	1.59a	1.60a	1.69bc	1.71abc	1.76bc	1.83c	0.07
Urine thiocyanate (mg/100 ml)	2.92a	2.98a	3.08a	3.14a	3.16a	3.27a	0.19NS

Source: Omole and Onwudike (1982)
Notes: Means within a row not followed by the same letter differ significantly
^a NS = no significant difference at (P<0.05)
nd = not determined

Cassava leaf may be very useful for rabbit nutrition as it compares favorably with alfalfa meal which has proved to be a very desirable feed for rabbits and is the largest single component of commercial rabbit feeds in the USA (Cheek 1987). It also compares favorably with Aspilia africana which is often used as the forage feed of rabbits in Africa.

Table 12. Amino acid profile in cassava leaves

Amino acid	Content (g/16g N)
Arginine	5. 1
Cystine	1.0
Glycine	4.6
Histidine	2.7
Isoleucine	4.3
Leucine	4.7
Lysine	7. 1
Methionine	1.1
Phenylalanine	3.6
Threonine	4.7
Tryptophan	1.0
Tyrosine	3.2
Valine	m6.4

Source: Devendra ( 1977)

Effect of processing on feeding value of cassava

There is no direct relationship between serum or urinary thiocyanate and growth performance and carcass characteristics in rabbits (Omole and Sonaiya 1981, Omole and Onwudike 1982). However, none of the studies reported for rabbits used a variety of cassava that is high in hydrocyanic acid. It is also possible that rabbits may be less sensitive to HCN intake than some other livestock species. It will be safe, however, to process the cassava products before they are incorporated in the diet.

There are various cassava processing techniques such as cooking, sun-drying, oven-drying, roasting, soaking, ensiling or fermentation and pulping of the tuber. No single processing technique will completely eliminate the HCN content of cassava products. While sun-drying may substantially reduce the HCN content of cassava tuberous roots, Omole (1977) suggested that the heating process during rapid drying may degrade the hydrolytic enzymes of glucosides and thereby prevent the release of free HCN. These views have been confirmed by Gomez et al. (1984) who indicated that more than 86% of the HCN present in cassava was lost during sun-drying, and also Devendra (1977) who indicated a reduction of HCN by about 50% in oven-drying at 36°C for 24 hours (table 13).

Table 13. The effect of sun-drying on the hydrocyanic acid (HCN) content of cassava leaves

No. hours in sun	HCN content (mg/ 100kg)
0 hour (fresh)	235
2 hours	470
4 hours	475
6 hours	470
8 hours	445
10 hours	324
24 hours (oven, 36°C)	120

Source: Devendra (1977)

Tewe et al. (1980) suggested that cassava peel, either sun-dried or oven-dried, contained apparently high amounts of cyanide. More studies are needed to determine the form of processed cassava products that will be safe to feed rabbits. The level of reduction of HCN that will be manifested by the processing techniques must be considered along with labor costs and the effects of such processing on other nutrients in the cassava products.

It can be concluded that up to 40 percent of cassava root meal may be incorporated in the diet of fryer rabbits and breeding does, without adverse effects on growth and reproductive ability. Also, when offspring of such dams are fed on cassava root meals, their life performance, carcass characteristics, urine and serum thiocyanate contents are not adversely affected.

It is desirable to feed methionine or fat supplements along with cassava peel meal to enhance the utilization of the feed. If no supplement is fed, the peel should not constitute more than 33% of the diet. Levels higher than 40 percent for both the cassava root meal and the peel should be investigated further, especially under varying dietary and processing conditions. Feeding trials with cassava leaves should be conducted to establish the most economic ways to use cassava leaves in rabbit diets.

References

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Eshiet, N.O., T.A. Omole, and AM Ademosun. 1979. The effect of feeding cassava root meal on the performance of fryer rabbits. If e Journal of Agriculture 2:2.

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Gomez, G., M. Valdiviesco, D. De la Guesta, and T.S. Salcedo. 1984. Effect of variety and plant age on the cyanide content of whole root cassava chips and its reduction by sun-drying. Animal Feed Science and Technology 11: 143-152.

Gramacho, D.D. 1973. Contribuçao ao estudo químico-technologico de feno da mandioca. Brascan Nordeste Serie Pesquisal 1(1):143-152.

Guin, A., and P. Andovard. 1910. Tapioca leaves for raising calves. Bull. Soc. Nat. Agric. France 68:776-779.

Hilditch, T.P., and P.N. Williams. 1974. The chemical constitution of natural fats. 4th edition. Chapman $ Hall. London.

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