Evaluation of mineral adequacy of natural browse species and concentrate ingredients for goats

Present study was conducted to estimate the mineral contents of few novel feedstuffs for goats and to find out the mineral adequacy/deficiency in browing/grazing situations under rural conditions. Seventeen leaf samples from trees and bushes were collected in two different periods of the year. The Ca and Fe contents were lower in summer leaves where as P and Cu was higher in summer leaves compared to winter leaves. Seventeen samples of tree leaves and bushes, seven samples of roughages and seventeen samples of concentrate ingredients were analyzed for macro (Ca, P, Mg) and micro (Zn, Cu, Fe and Mn) minerals. Statistical analysis between different categories of feed ingredients revealed that the Ca and Mg contents (%) were higher in tree leaves compared to roughages and concentrates where as contents of P (%) and Zn (ppm) was (P < 0.01) higher in concentrates. A model calculation suggested the deficiency of P, Zn, Cu and Mn in sole leucaena and neem leaf based diets whereas deficiency of P and Mn in sole buffel grass diets for goats.

Introduction

Ruminants fed low quality forages require supplementation with critically deficient nutrients to optimize productivity. The concentration of nutritional research effort on diagnosis and correction of mineral deficiencies is highly commendable particularly where livestock on high quality feeds are not producing to expectation. However, this policy is much less relevant when, because of an imbalanced feed animals are at subsistence, or at only moderate levels of production. Compounded mineral supplements are relatively expensive, often not available in small quantities, they are often out of the reach of smallholder farmers, or are difficult for them to obtain. In this scenario, a best strategy would to use local and natural sources of minerals as a means of economising on the need to purchase proprietary mineral mixtures (Preston and Leng 1987). The mineral content in soil keeps changing due to pressure on land for maximum crop production, fertilizer application, rain and natural calamities, which may alter their contents in feeds and fodders thereby affecting the mineral status of animals (Underwood and Suttle 1999). Certain minerals are essential in the diets of animals and influence livestock production (Kincaid 1988). The first step in assessing the mineral status of animals is to find out the mineral adequacy of diet, which can form base line for mineral supplementations (Samokhin 1982). Dietary deficiencies and imbalances of these minerals can result in poor growth, failure of reproduction, wasting diseases, skin disorders, non-infectious diseases, , non-infectious abortions, anemia, bone abnormalities, tetany and many other disorders (Underwood 1981). Present study is conducted with a view to find out mineral status of tree leaves, roughages, concentrate ingredients to determine the mineral adequacy of the diet for goats. The information thus generated will be useful in formulating mineral mixtures for goats.

Materials and methods

Collection of samples

Seventeen tree and bush leaves namely Indian gum arabic (Acacia nilotica), Indian tree of Heaven (Ailanthus excelsa), Sacred Fig (Ficus religosa), West African Sickle Bush (Dichrostachys nutans), subabul (Leucaena leucocephala), Cluster Fig (Ficus glomerata), Prosopis cineraria (L.) Druce, neem (Azadirachta indica), Morus alba L, Indian jujube (Zizyphus mauritiana),Ficus bengalensis L., Balarites aegyptica L., Alzebia lebbek (L.) Bentham, Pithocellobium dulce (Roxb) Benth, Tooth Brush tree (Salvodora perisica), Capparis horrida, Chlorodendron phlemides L. were collected in two times. First sampling was done in month of January (representing Winter) and second sampling was done in the month of June (representing Summer). Roughage samples like buffel grass (Cenchrus celiaris), Desmostachys bipinnata (L.) Staph, Cynodon doctylon, blue panic (Panicum antidotale) grass, Pearl millet (Pennisetum typhoideum) fodder in two stages and Chickpea (Cicer arietinum) straw were collected from the institute premises. Few concentrate ingredients such as Indian mustard (Brassica nigra) cake (with oil and de-oiled), de-oiled sunflower (Helianthus annus) cake, de-oiled soybean (Glycine max) cake, Cluster Bean (Cyamopsis tetragonaloba) meal, malt sprouts, rice (Oryza sativa) polish and de-oiled rice bran, jowar (Sorghum vulgare) grain, Pearl millet grain, maize (Zea mays) grain, barley (Hordeum vulgare) grain, Chickpea (Cicer arietinum) husk, Redgram (Cajanus cajan) husk, , Flax (Linum usitatisimum) seed cake, Sesame (Sesamum indicum) cake and commercial pelleted feed were collected from local markets.

Processing of the samples

All the samples are initially dried in the hot air oven 100°C and ground to pass through laboratory Cyclotec Mill. Approximately, 1-2 g of the feed was accurately weighed in a silica basin and charred to remove the smoke and ashed in a muffle furnace. Acid extract was prepared by quantitative transfer of ash to a dried clean glass beaker to which approximately 20 ml of hydrochloric acid was added. This was boiled for 5 min and filtered through Whatman filter paper No.1 into a 100 ml volumetric flask. The filter paper was washed with hot distilled water three times and the volume was made up to mark by distilled water. Minerals such as Mg, Fe, Zn, Cu, Mn were estimated by atomic absorption spectrometer (GBC, Avanta PM) using acetylene as fuel and air as oxidant. Ca was estimated by AOAC (1984) procedure. Total P in feed samples was estimated by Ward and Johnson (1962) method.

Statistical analyses

The statistical significances between tree leaves and bushes, roughages and concentrates were analyzed using mixed model least squares and maximum likelihood computer program (PC-2) (Harvey 1990). Similarly, the statistical significances between different tree leaves/bushes between two seasons were analyzed as per Snedecor and Cochran, (1968).

Results and discussion

Categorical analysis of feeds

The average content of AIA, Fe, Cu and Mn (ppm) were found to be similar (P>0.05) in all categories of feedstuffs i.e. tree leaves, roughages and concentrates. The total ash content was higher in tree leaves and roughages in comparison to concentrates. The Ca and Mg contents (%) were higher in tree leaves compared to roughages and concentrates where as contents of P (%) and Zn (ppm) was higher in concentrates (Table 1).

Table 1: Mineral contents of feeds for goats
	Total Ash*	AIA	Ca**	P**	Mg**	Zn**	Cu	Fe	Mn
	%					ppm
a) Tree Leaves
Indian gum arabic	7.01	1.36	2.29	0.11	0.67	47	17	580	24
Indian tree of heaven	9.46	2.23	2.8	0.26	0.62	90	10	872	42
Sacred Fig	13.2	2.46	3.66	0.17	0.32	35	10	318	34
West African Sicklebush	7.57	1.05	2.68	0.14	0.34	42	10	515	45
Subabul	10.1	0.92	3.01	0.13	0.74	33	7	715	48
Cluster Fig	13.2	5.11	2.87	0.14	0.74	33	7	573	34
Proscopis cineraria (L.)	6.5	1.36	2.6	0.09	0.29	37	11	613	29
Neem	9.3	0.68	1.76	0.15	0.74	45	8	704	27
Morus alba (L.)	15.6	6.32	1.82	0.103	0.57	40	9	901	31
Indian jujube	9.4	1.09	3	0.08	0.45	59	13	632	71
Ficus bengalensis L.	10.7	2.45	3.79	0.11	0.44	40	11	483	26
Balarites aegyptica L.	9.56	1.53	3.15	0.11	0.60	50	13	719	36
Alzebia lebbek L.	9.58	1.87	2.9	0.12	0.33	41	13	726	23
Pithocellobium dulce	11.9	2.73	2.85	0.18	0.47	33	11	803	45
Tooth Brush tree	30.4	1.4	8.62	0.07	0.48	56	12	457	26
Chlorodendron phlemides L.	15.6	1.43	4.18	0.2	0.77	53	15	925	28
Capparis horrida L.	17.4	1.15	4.49	0.1	0.95	61	13	489	39
Average	12.1^b	2.07	3.32^a	0.13^b	0.56	47^b	11^b	649	36
SEM	1.37	0.37	0.38	0.01	0.05	3	0	41	3
Max	30.4	6.32	8.62	0.26	0.95	90	17	925	71
Min	6.47	0.68	1.76	0.07	0.29	33	7	318	23
(b) Roughages
Buffel grass	12.2	2.90	1.22	0.17	0.26	77	14	646	20
Desmostachys bipinnata (L.) Staph grass	5.6	2.18	1.45	0.01	0.14	53	15	572	22
Cynodon dactylon grass	15.8	2.56	1.05	0.17	0.29	35	9	1220	67
Blue Panic grass	14.1	1.21	0.89	0	0.04	87	17	487	27
Pearl millet (tender)	15.8	2	1.39	0.37	0.78	132	20	869	54
Pearl millet (mature)	8.71	4.12	0.46	0.21	0.21	44	21	659	6
Chickpea straw	7.90	1.36	1.62	0.03	0.5	67	13	947	12
Average	11.5^b	2.33	1.15^b	0.14^b	0.32	71^ab	16^ab	771	30
SEM	1.54	0.38	0.15	0.05	0.09	12	2	96	8
Max	15.8	4.12	1.62	0.37	0.78	132	21	1220	67
Min	5.64	1.21	0.46	0.00	0.04	35.0	9	487	6
Sorghum grain	0.94	ND	0.10	0.3	0.04	49	4	128	9
Pearl milletgrain	0.79	ND	0.14	0.4	0.04	203	4	281	17
Maize grain	0.93	ND	0.16	0.2	0.04	50	2	175	10
Barley grain	0.67	ND	0.19	0.3	0.04	61	4	147	21
Chickpea husk	4.75	ND	0.59	0.4	0.05	48	8	1451	100
Redgram husk	4.65	ND	0.66	0.3	0.06	100	12	883	38
Indian mustard cake (with oil)	6.93	ND	0.68	1.0	0.06	83	17	492	55
Flax seed cake	17.6	ND	0.69	0.8	0.05	103	26	2197	79
cake	6.58	ND	1.39	0.8	0.05	109	27	889	44
Pelleted Feed	6.93	0.7	0.9	0.38	0.25	46	20	668	10
Deoiled Indian mustard cake	7.41	0.59	1.2	0.65	0.85	108	18	517	40
Rice Polish	11.3	4.43	0.6	0.69	0.75	178	13	765	77
Deoiled Sunflower cake	7.87	1	0.8	0.46	0.51	500	48	817	10
Deoiled Soybean cake	17.6	0.74	0.79	0.27	0.1	118	25	709	23
Cluster Bean meal	5.28	0.23	0.4	0.19	0.11	104	17	563	23
Malt Sprouts	6.13	0.9	0.8	0.28	0.2	105	13	771	7
Deoiled Rice Bran	11.7	5.05	0.5	0.46	0.69	114	14	517	57
Average	6.94^a	1.71	0.62	0.46	0.23	122	16	704	36
SE	1.26	0.67	0.09	0.06	0.07	26	3	123	7
MAX	17.6	5.05	1.39	1.00	0.85	500	48	2197	100
MIN	0.67	0.23	0.10	0.19	0.04	46	2	128	7
For average values within columns ab Means are different at P < 0.05 ‘ND‘ denotes not estimated.

Mineral adequacy of the feeds

Tree and bush fodders

All the tree/bush fodders contained adequate Ca (> 0.7%). The P content (%) was deficient in all the samples (< 0.5 %). The contents of Mg and Zn were adequate in all the samples (>0.2 % for Mg and > 30 ppm for Zn). Cu content (ppm) was found to be adequate only in Indian gum arabic and Chlorodendron phlemides L (> 15 ppm) and deficient in rest. Fe content (ppm) was found to be excess in all the fodders analysed (>100). Mn content (ppm) was found to be sufficient (>30) in ten out of seventeen with highest being Indian jujube and lowest in Albezia lebbek.

Roughages

Except mature pearl millet fodder, all the roughages had adequate Ca (>0.7 %). The P content (%) was deficient in all the samples (< 0.5 %). Except Desmostachys bipinnata (L.) grass, all the roughages had more than 0.2 % Mg indicating adequacy. The content of Zn and Fe were adequate in all the roughages. Except Cynodon dactylon grass all the roughage had adequate copper. Excepting Cynodon dactylon grass and tender pearl millet fodder, all the roughages had less Mn (< 30 ppm).

Concentrates

Excepting Sesame cake, pelleted feed, de-oiled sunflower cake, de-oiled soybean cake and malt sprouts, other concentrate ingredients analysed were found to contain low calcium (<0.7%). Indian mustard cake, Flax seed cake, Sesame cake, de-oiled Indian mustard cake and rice polish has adequate P (>0.5%). Pelleted feed, de-oiled Indian mustard cake, rice polish, de-oiled sunflower cake, malt sprouts and de-oiled rice bran have sufficient Mg (0.2%). All the analysed concentrate ingredients have sufficient Zn and Fe (> 30 ppm for Zn and > 100 ppm for Fe). Cu content was low (<15 ppm) in all grains, chunnies, rice polish and malt sprouts. Mn content was low (< 30 ppm) in grains, pelleted feed, de-oiled sunflower cake, de-oiled soybean cake, cluster bean meal and malt sprouts.

Seasonal analysis of tree leaves

The total ash, AIA, Ca and Fe content of different tree leaves and bushes was different where as P, Mg, Zn, Cu and Mn were found to be similar in different tree leaves (P > 0.05). The AIA, Ca and Fe contents were lower in summer season where as P and Cu was higher in summer leaves compared to winter leaves. Season of the year did not affect total ash, Mg, Zn and Mn content of the leaves (Table 2).

Mineral adequacy of diet

The mineral adequacy of the diet was estimated using requirements given by Haenlein (1992) and Meschy (2000). Three hypothetical dietary situations were assumed. In the first scenario, the diet was assumed as sole subabul leaf. In this type of situation, the minerals such as P, Zn, Cu and Mn were found to be deficient. In the second situation, the diet was assumed as sole neem leaf. In this type of situation also, P, Zn, Cu and Mn were found to be deficient. In the third situation, the diet was assumed as sole buffel grass diet. In this type of situation, P and Mn were found to be deficient (Table 3).

The variations in the mineral contents amongst different fodders are attributable to plant species, stage of maturity, soil characteristics and agro-climatic conditions (Reid and Horvath 1980). The high level of iron observed in the samples is due to unavoidable soil contamination. In the present study, the concentrations of Ca, P, Mg, Zn, Fe and Mn were reduced as the bajra fodder matured whereas Cu and AIA contents were increased. Most investigators have observed a rise with advancing maturity of the plant in the concentrations of Si, Al and Cr and a fall in Cu, Sn, Co, Ni, Mo, Fe and Mn (Underwood 1977). As plants mature, mineral contents decline due to a natural dilution process and translocation of nutrients to the root system. However, it is interesting to note that Cu status of grazing and housed cattle in the Netherlands indicate that differences exist in the availability of Cu from herbage at different growth stages. The seasonal variations in trace elements of plants could be due to change in moisture status of the soil, affecting trace element availability to plants, botanical composition of herbage, morphological characteristics of plants such proportions of leaf to stem, seed and palatability (Underwood 1977). The extent of deficiency, is dependent on the type of accompanying feed as in the case of straws and stovers which contain several anti-nutritional factors like silica, lignin and oxalates, and the physiological status of the animal (McDowell 1996). Similarly, tannins present in leaf fodders might influence trace mineral absorption.

Endogenous losses of Ca and P might be more related to dry matter intake than to the bodyweight. True absorption coefficient of P is probably higher for goats (70-75%) than for other ruminant species. Ca and phosphorus requirements for pregnancy are higher because of the frequency of multiple fetuses. The requirements for growth are lower than for calves. Nevertheless, Ca and P content of goat milk (1.3 g Ca/l, and 0.9 g P/l, respectively) are very close to those of cow milk. Several results indicate that goats are less sensitive to Cu toxicity than sheep and cattle and can tolerate higher levels of Cu in their diets (Meschy 2000). The literature on mineral requirements of goats and sheep suggested that they differ from production function (growth, maintenance and lactation). However, mineral requirements found in literature are given in ranges (Haenlein 1992 for goats).

Conclusion

Acknowledgements

The authors gratefully acknowledge Director, Central Institute for Research on Goats, Makhdoom, Farah (PO) for guidance and providing necessary facilities to carry out the research work. The authors further express sincere thanks to Dr. T. R. Preston, Editor, Livestock Research for Rural Development for excellent suggestions in improving the manuscript.

References

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Table 3: Estimation of mineral adequacy of diet
Dietary situation	Ca¹	P¹	Mg¹	Zn²	Cu²	Fe²	Mn²
Dietary situation	% of diet			ppm
Requirement	0.7	0.5	0.2	50	10	100	50
Subabul leaf diet	3.01*	0.13**	0.74*	33**	7**	715*	48**
Neem leaf diet	1.76*	0.15**	0.74*	45**	8**	704*	27**
Buffel grass diet	1.22*	0.17**	0.26*	77*	14*	646*	20**
¹requirements were adapted from Haenlein 1992. ²requirements were adapted from Meschy 2000. * Adequate ** Not adequate