Evaluation of nondigested carbohydrates in hydroxypropylated tapioca starch.

In vitro and in vivo digestibilities of hydroxypropyl starch were investigated to determine an appropriate nondigested carbohydrate assaying method for hydroxypropyl starch. Hydroxypropyl tapioca starch (HPTS), with a 0.338 degree of substitution, was used as a hydroxypropyl starch source. Practically all nondigested carbohydrate in HPTS was low molecular weight and was not precipitated in 78% ethanol. The contents of nondigested carbohydrate in HPTS and in effluents of ileorectomized rats fed the HPTS diet obtained by the AOAC 2001.03 (enzyme-gravimetric-HPLC method) were almost the same, 56% and 59%, respectively. The recovery of hydroxypropyl groups from ileorectomy effluents was 98%. The AOAC 2001.03 method is suggested to be appropriate in determining the content of nondigested carbohydrates in hydroxypropyl starch.

Improvement of organoleptic quality of retted cassava products by alkali pretreatment of roots and addition of sodium nitrate during retting.

Alkali pretreatment of cassava roots before retting and addition of sodium nitrate during retting were used to manipulate the metabolism of microorganisms involved in cassava (Manihot esculenta Crantz) retting, as a method for removing the characteristic offensive odour of retted cassava products. Odour was assessed by organoleptic methods. The characteristics of fermentation of cassava by the traditional method (control) were as follows; aerobic mesophilic count (APC) on nutrient agar (NA) at 30 degrees C/48 h, attained a maximum of 2.3 x 10(7)/ml retting juice while counts on de Man Rogosa and Sharpe agar (MRS) at 30 degrees C/48 h were 1.6 x 10(8)/ml. Maximum titrable acidity was 0.062% lactic acid by weight of retting juice. Cassava was retted in 3 days and the product exhibited characteristic offensive odour. Addition of NaNO3 into retting water effectively removed odour at a concentration of 0.3 g/l. Maximum APC on NA/30 degrees C/48 h was 6.8 x 10(6)/ml. Counts on MRS/30 degrees C/48 h exceeded 2.4 x 10(9)/ml. Retting was complete in 3 days with a final titrable acidity of 0.068% of retting juice. Removal of odour likely resulted from selection of homo-fermentative lactic acid bacteria, thus producing mostly odourless lactic acid. Alkali pretreatment of roots before retting was efficacious in removing odour at a concentration of 10 g/l for 30 min. This fermentation was characterized by APC on NA/30 degrees C/48 h of 5.4 x 10(6)/ml; MRS/30 degrees C/48 h reached a maximum of only 10 x 10(4)/ml and correspondingly low titrable acidity of 0.003%. Low counts of lactic acid bacteria correlate well with the absence of odour in this sample. Both treatments did not adversely affect the detoxification process, yielding "foo-foo" with HCN levels lower than 10 mg/kg. Residual nitrates and nitrites of 30 mg/kg in the sodium nitrate-treated sample were also within the safe limits of 156 mg/kg allowed in many countries. Organoleptically improved samples were acceptable to the public.

The potential for biotechnology to improve the nutritional value of cassava.

Cassava, a starch-rich plant that has poor protein content and usually poor vitamin content, feeds about 600 million people each day. When cereals can no longer be grown because of soil fertility problems, it is often still possible to grow cassava. It is the third most important source of dietary calories in the tropics, and reliance on the crop is especially high in West and Central Africa. The International Laboratory for Tropical Agricultural Biotechnology is promoting research to improve cassava productivity and is a leader in developing genetic engineering to improve the quantitative and qualitative traits of this essential food crop.

Influence of dietary factors on nitrogen partitioning and composition of urine and feces of fattening pigs.

An experiment was conducted to investigate the influence of dietary factors on the partitioning of nitrogen excretion and on the pH and composition of urine and feces of fattening pigs. Sixteen male hybrid pigs of 80 to 90 kg BW were allotted to one of four diets: based on grains, by-products, grains plus tapioca, or grains plus sugar beet pulp. Diets were formulated to have similar contents of NE and CP and a similar lysine:NE ratio. Diets differed in nonstarch polysaccharide content (NSP) and dietary electrolyte balance (dEB). During an 8-d period, urine and feces were quantitatively collected daily in metabolism cages and mixed to a slurry. There was no effect of the diet on total nitrogen excretion (P > .05). However, the nitrogen excretion pattern differed between diets (P < .001). Pigs fed the by-product- and the sugar beet pulp-based diets excreted less nitrogen via urine and more nitrogen via feces than pigs fed the grain- and tapioca-based diets. The type of diet significantly affected the pH of urine, feces, and slurry. The pH of slurry from pigs fed the sugar beet pulp-based diet was .44 to 1.13 units lower than that of slurry from pigs fed the other three diets. An increased dietary NSP content reduced the pH of feces and slurry. A decreased dEB reduced the pH of urine and slurry. We conclude that dietary NSP influences the partitioning of excretory nitrogen between urine and feces. Dietary NSP and dEB can influence the pH of urine, feces, and slurry.

[Feed intake and milk production in dairy cows fed whole fat soybeans]. / Futteraufnahme und Milchleistung bei Verfütterung von Vollfett-Sojabohnen an Milchkühe.

In two experiments (E 1, E 2) two different basic diets were fed to 36 diary cows with addition of 1 or 2 kg of full fat soya beans (SB) or without SB for six weeks. The cows were fed individually. The basic diet consisted of 49% grass silage, 23% maize silage and 21% hay, supplemented with 7% manioc (% DM) in E 1 and of grass, supplemented with 2.0 kg maize silage, 3.0 kg hay and 1.5 kg manioc (kg DM/cow.d) in E 2. The basic diet used in E 1 and the grass in E 2 were offered ad libitum. Further a mixture of 1 kg SB, soya bean meal and manioc (Treatment 1), a mixture of 2 kg SB and manioc (Treatment 2) and a mixture of soya bean meal and manioc (Treatment 3, control), respectively, was supplemented to achieve diets with equivalent concentrations of energy and protein. Depending on the daily milk yield a concentrate was fed to high yielding cows (> 21.5 kg milk in E 1 and > 25.0 kg milk in E 2, respectively). The addition of 1 kg SB increased the forage intake in both experiments by 1.2-1.5 kg DM/cow.d significantly, while the addition of 2 kg SB increased the forage intake only in E1 to the same extent. The mean total DMI was 19.2 kg in E 1 and 17.7 kg in E 2, respectively. The daily milk yield was not influenced by addition of SB. The average milk yield was 28.8 kg and 26.7 kg in E 1 and E 2, respectively. The milk fat content increased significantly in E 1 by 0.3-0.4% with no respect to the amount of the supplied SB (4.11% vs. 3.74%). In E 2 the milk fat content increased only slightly (3.84% vs. 3.74%). Milk protein content was not influenced in E 1, but decreased in E 2 after addition of 2 kg SB.

Protein and energy value of dehydrated poultry excreta in diets for feedlot cattle.

Four Holstein steers (222 kg) with cannulas in the rumen and proximal duodenum were used in a crossover design experiment to evaluate the energy and protein value of dehydrated poultry excreta (DPE). Dietary treatments contained (DM basis) 4% alfalfa hay, 8% sudangrass hay, 49% flaked barley, 8% cane molasses, 3% yellow grease, .8% urea, 1.4% limestone, .3% mineral salt, and .4% chromic oxide, plus 25% of either tapioca pellets or DPE. The DPE contained 42% ash and 27% CP (6% true protein). Substituting DPE for tapioca decreased the DE value of the diet (P < .01). The estimated DE value of the DPE was 1.36 Mcal/kg (.34 Mcal NEm/ kg). There were no treatment effects (P > .10) on microbial N flow to the small intestine or ruminal microbial efficiency (grams of microbial N/kilogram of OM fermented). The addition of DPE increased (P < .05) the flow of non-ammonia and feed N to the small intestine. The estimated ruminal escape N value of DPE was 22%, although very little of this was true protein. Dehydrated poultry excreta did not increase (P > .10) flow of alpha-amino N to the small intestine. Ruminal degradability of uric acid was 96%. Total tract true digestibility of N in DPE was 84%. It is concluded that the NE value of DPE is markedly overestimated in current tables of feeding standards. Less than 10% of the N in DPE escapes the rumen as true protein N.

Consumer acceptability of stiff porridge based on various composite flour proportions of sorghum, maize and cassava.

A study was conducted to determine consumer acceptable proportions of flours in sorghum (var. serena) and maize or sorghum, maize and cassava composite flours. Breeder's serena flour extracted at 75 percent was mixed at various proportions with maize or with maize and cassava to constitute composite flours. The various composite flours were made into stiff porridge and presented to a group of panellists for sensory evaluation. The evaluation was conducted by scoring on a hedonic scale of 0-5 for poor to excellent, respectively, for the parameters colour, texture, flavour, taste and overall acceptability. The responses were analysed statistically. Alternatively the panellists were allowed to eat ad-lib any of the presented samples which appealed to them. The results demonstrated that slight incorporation (< 10%) of sorghum (var. serena) to maize flour leads to reduction in consumer acceptability. However, increased incorporation of sorghum in excess of 10 percent leads to no significant decrease in consumer acceptability until a level of 30 percent incorporation is exceeded. In sorghum, maize, cassava composite flours the formulation of 30:40:30, respectively, was found to be most acceptable. It is suggested that at this combination of flours desirable textural characteristics of the porridge overrides other factors in contributing to its acceptability.