Studies in vitro and in vivo on the nutritive value of whole cottonseed (Gossypium Sp) for sheep
| Main Author: | Ismartoyo, Ismartoyo |
|---|---|
| Format: | Thesis |
| Bahasa: | eng |
| Terbitan: |
, 2012
|
| Subjects: | |
| Online Access: |
http://repository.unhas.ac.id/handle/123456789/2444 |
Daftar Isi:
- ABSTRACT Studies in vitro and in vivo on the nutritive value of whole cottonseed (Gossypium sp.) for sheep By : Ismartoyo, Ph.D. in Ruminant Nutrition, Aberdeen University, Scotland, United Kingdom A series of investigations was undertaken to investigate the nutritive value of whole cottonseed (WCS), rumen microbial degradation of oilseeds and legume seeds, and the effects of gossypol on rumen microbial fermentation in vitro and in vivo. An HPLC method was developed for the analysis of gossypol concentrations in WCS and in rumen liquor. Six oilseeds namely WCS (Gossypium sp.), mustard seed (Brassica sp.), linseed (Linum sp.) and three cultivars of rape seeds (Brassica spp.) (cv. Bienvenu, cv. Libravo and cv. Samourai) were incubated with rumen contents in consecutive batch culture (CBC) and examined for their microbial DM degradation and fermentability. Another selection of legume seeds namely narbon seed (Vicia narbonensis), mungbean seed (Phaseolus aureus), two cultivars of cowpeas (Vigna unguiculata), and lablab seed (Lablab purpureus) (cv. Highworth) were also examined. The oilseeds showed lower DM losses, gas production and volatile fatty acids (VFA) concentration than the legume seeds. WCS was consistently had low fermentation characteristics in CBC. However, removal of fat content from WCS did not improve the microbial fermentation suggesting that the fat content was not the primary factor which contributed to the low fermentation of WCS in CBC. Mixed rumen microbes appeared to adapt to prolonged exposure to gossypol [2,2'-bi(8-Formyl-1,6,7 trihydroxy-5-isopropyl-3-methyl napthalene)] in CBC. In contrast fractionated rumen bacteria did not appear to adapt to the prolonged exposure of gossypol (1 mM) in culture. The depression in the DM loss of grass hay (GH) treated gossypol suggested that the activity of cellulolytic bacteria might be severely affected by gossypol. The presence of gossypol at concentrations of 1 to 10 mM resulted in the death of 50 to 75% of the rumen ciliates when GH served as substrate. The decrease in DM losses of GH was inversely correlated with the gas produced and the concentrations of gossypol. The attachment the rumen fungus Neocallimastix frontalis strain RE1 to cellulose and cellulolysis by this fungus were also inhibited by the presence of gossypol in culture. Gossypol at a concentration of 20 *M resulted in a depression of growth, multiplication, protein content of cells, and the death of some cells in culture. It is thought that gossypol may react with protein and phospholipid of cell membranes. Gossypol may also bind with components of the medium such as protein, lipid and minerals which reduce the availability of nutrients for cell growth. Dietary supplementation of WCS at 500g d-1 (0.37 of the diet) depressed DM, NDF and ADF digestibility and total counts of rumen fungi, rumen protozoa Polyplastron sp. and Diploplastron sp. in the rumen of sheep. Total counts of the rumen microbes returned to initial levels 3 weeks after the end of the experiment when a normal basal diet without WCS was fed. The concentrations of gossypol ('unbound' and 'acetone-soluble bound' gossypol) in WCS was 1.93 g kg-1. The unbound gossypol in the rumen of sheep fed WCS was considered very low (possibly below 0.5 ???g ml-1). It was thought that most of the dietary free gossypol may have been bound in the rumen. It was concluded from this study that gossypol affects the numbers of rumen protozoa (the apparent reduction on the numbers of rumen protozoa in the rumen of sheep fed WCS suggests that WCS might be utilised as antiprotozoal agent to modify the composition of rumen microbes and the fermentation) and fungi, but was not the only factor influencing the low degradability and fermentability of WCS. Other factors such as fat, fibre, fractions within fibre, and the presence of other antinutrient such as tannins, and pigments in WCS and/or combination of these factors may have contributed to the low fermentation in vitro and in vivo of WCS. Although of high nutrient value, the results suggest that inclusion of WCS in the diet of sheep at 500 g d-1 (0.37 of the diet) altered the patterns of digestion and the composition of rumen microbes in the rumen. Despite of the fact that rumen microbes appeared to adapt to gossypol in culture, prolonged feeding of WCS may cause detrimental effects on rumen microbes. Keywords : Whole cottonseed, Grass Hay, In Vitro, In Sacco, In Vivo, Nutritive value, Sheep