Hydrolysis of phytic acid and its availability in rabbits

The impact of humic acid additives on mineral metabolism of rabbits in the postnatal period of ontogenesis

Humic acids are characterized by chelating properties due to which they are able to influence the mineral metabolism in animals. Rabbits have species-specific characteristics of mineral metabolism, which distinguishes them from most species of mammals. For the experiment, 16 rabbits of 45-day-old of Hyplus breed were divided into the experimental and control group of 8 rabbits in each. The animals were 15 days in the preparatory period. The rabbits of the experimental group received humic acid additive individually with water in the amount of 5 mg/kg, the rabbits of the control group received pure water in the same amount. The ability of humic acid additive to increase the content of calcium, ionized calcium, iron, to correct the content of copper and zinc, and also to increase the activity of alkaline phosphatase in the blood serum of rabbits of the experimental group has been proved. We observed the early effect of the humic acid additive on increasing the content of iron and calcium ionized and a later effect on the activity of alkaline phosphatase and an increase in the content of copper in the blood serum. The influence of humic acid additive on the distribution of calcium, phosphorus, manganese, copper and zinc in bone tissue is determined. According to a histological study, there was a significant increase in the number of layers of osteons and osteoblasts in the bone tissue of the femur, an increase in the number of osteons and osteoblasts in the bone tissue of the sternum and an increase in the number of columns of chondrocytes and an increase in the number of chondrocytes in the column in the cartilaginous tissue of the sternum. The results of a histological study of bone tissue, together with an increase in structural macroelements in it and redistribution of osteotropic trace elements in the blood and bone tissue suggest the possibility of using a humic acid additive to intensify the growth and mineralization of bone tissue, which can improve the state of bone tissue of rabbits in the postnatal period ontogenesis.

Direct and correlated responses to selection in two lines of rabbits selected for feed efficiency under ad libitum and restricted feeding: III. Digestion and excretion of nitrogen and minerals

Two rabbit lines have been created to result in better feed efficiency: the ConsoResidual line was selected for a lower residual feed intake under ad libitum feeding, and the ADGrestrict line was selected for higher ADG under restricted feeding (-20% of ad libitum). The present study aimed to analyze the digestion and excretion of N and minerals from 29 to 63 d of age of these 2 lines compared with an unselected control line (G0) under 2 feeding levels (ad libitum or restricted). The ADGrestrict line had greater digestibility compared with G0 (+1.3% for OM and N; < 0.05), and the ConsoResidual line had intermediate values. There was no genetic line effect on the digestibility of N and P and on minerals concentrations (P, Zn, and Cu) in the feces and in the urine. The N balance was improved for the 2 selected lines (+5%; < 0.05), leading to a reduced N output through the feces (0.06 g/d compared with G0; < 0.001) and the urine (-0.07 g/d; < 0.05) and to an improved N retention ratio (+3% compared with G0). Over the whole fattening period (d 29-63), significant differences were observed among lines only when fed ad libitum, with 13% greater DM fecal output and 5% greater N fecal output for G0. The N excretion in urine was 2 g less in the 2 selected lines, leading to a reduction of total N release of 4.4 g (compared with G0). The P excretion in feces (12 g) or urine (0.1 g) did not differ among the 3 lines. Over the whole fattening period and for ad libitum-fed rabbits, the 5% improvement in feed efficiency ( < 0.01) for the 2 selected lines corresponded to 400 g less feed intake (-8%) and to 20 g less N intake. The fecal excretion of the ADGrestrict and ConsoResidual lines were reduced by 200 g DM ( < 0.01), corresponding to 417 g fresh matter and 5 g of N. The excretion in minerals (P, Zn, and Cu) was not affected by the line. The feeding level strongly reduced the fecal and urine outputs (-50 and -60%, respectively; < 0.001). Higher digestibility coefficients ( < 0.001) were found in restricted-fed rabbits for OM (+6%), N (+8%), and P (+11%). The N balance was substantially improved by the restriction, with 40% less total (feces + urine) N excretion ( < 0.001). The P balance was improved by the restriction (0.469 vs. 0.360). Over the fattening period, the P fecal output was 37% less (-6 g) with 24% less feed intake and the Zn and Cu outputs were reduced by 27 (-130 mg) and 29% (-30 mg), respectively.

Bioavailability of phytic acid–phosphorus and magnesium from lentils (Lens culinaris m.) in growing rats: Influence of thermal treatment and vitamin-mineral supplementation

OBJECTIVE

We sought to improve the nutritive utilization of Lens culinaris M. variety vulgaris cultivar Magda-20 in growing rats by autoclaving the lentil seeds at 120 degrees C for 30 min at an internal pressure of 1 atm and by supplementing the rats with a vitamin-mineral premix.

METHODS

Nutritional assessment was based on chemical analysis of total phosphorus, free phosphorus, phytate, magnesium, neutral detergent fiber, and acid detergent fiber contents of the lentils and the digestive and metabolic use of phosphorus and magnesium by the growing rats.

RESULTS

The net absorption of phosphorus was greater than the amount of non-phytate phosphorus ingested by the animals fed diets of raw and autoclaved lentil flours. Vitamin-mineral supplementation of raw and autoclaved lentil flour resulted in a significant increase in dietary intake and net absorption of phosphorus and magnesium. For all of the experimental diets tested, there was a direct correlation between phosphorus or magnesium balance and weight gain (r = 0.91 and 0.80, respectively) and between phosphorus or magnesium balance and nitrogen balance (r = 0.91 and 0.87, respectively).

CONCLUSIONS

Part of the phytate-phosphorus from raw and autoclaved lentil flour was available during digestion, and hardly any phytate was detected in the feces. Supplementation of raw lentil flour with a vitamin-mineral premix was the most effective treatment for increasing daily food intake, body weight gain, and nutritive use of phosphorus and magnesium.