Beneficial Effect of Zinc Supplementation on Reproduction in Rats Fed Rapeseed Protein Concentrate

Abstract

Three groups of 33 90-day-old female Sprague-Dawley rats were fed, ad libitum, the following diets for 2 weeks before breeding. Diet 1 (D1) contained 20% protein from casein, diet 2 (D2) had the same level of protein from Tower rapeseed (Brassica napus) protein concontrate (RPC) and diet 3 (D3) was the same as D2 with a zinc supplement (70 mg/l) in the drinking water. From each group 6 animals were killed before breeding and 5–9 animals were killed at 1 and 2 weeks of gestation and post-partum. From each rat, blood, thyroids, liver and femur were collected for the determination of zinc, copper, iron, manganese, calcium and magnesium. As a measure of the reproductive performance, body weight, number of pups in the uterus or delivered live or dead, and gestation days before parturition were recorded. The pups were examined for obvious deformities and also analysed for the above mineral elements by atomic absorption spectroscopy. In group D2, levels of zinc in maternal serum, liver, femur and in the pups were significantly lower than the comparable levels in the other two groups. The zinc supplemented RPC-fed group did not show the anorexia experienced by the unsupplemented group and there was neither a significant difference between reproductive performances of groups D1 and D3 nor was there any significant difference between the zinc levels determined. It was concluded that the toxic symptoms caused by RPC feeding were attributable to zinc deficiency probably caused by the high phytate level in the RPC.

Effects of Canola Meal on Absorption and Tissue Levels of Trace Minerals in Rats

“…'lHrO in ground sucrose) at 2.5 times NAS-NRC (1978) recommended levels (AIN 1977) f {Actual dry matter percentages of diets, left to right: 96.6, 90.2, 90.3, 90.3, 90.3 (Bille et al 1983a,b (Luecke et al 1970). Shah et al (1976) reported similar responses while Eklund and Agren (1978) (8) 120 (8) n7 (8) r15 (8) 7.6 0. '77c (1) 0.94b (8) 0.84c (8) 0.94b (7) 1.10a (1) 0.03 2.60 (1) 2.68 (8) 2.30 (8) 2.6s (8) 2.4r (7) 0.l8 14.1b ('7) l8.4ab (8) 19.7a (8) 18.lab (8) 19.5a (8) 0.96 r-35a (7) t.32a (8) r.42a (8) 1.07b (8) $Number of observations/group shown in parentheses.…”

Canola and Rapeseed

“…A 300 ppm dietary Zn was necessary to prevent the reduction in food consumption, weight gain, and plasma Zn levels caused by 20.0% rapeseed flour. Shah et al (1976Shah et al ( , 1979Shah et al ( , 1980) also observed Zn deficiency in rats feed rapeseed protein concentrate at 20.0% protein level; however, a lower level ofZn supplementation (150 ppm in the diet or 70 Jlg/ ml in the drinking water) was found sufficient to overcome the Zn deficiency symptoms.…”

Choosing between crops: aspects that affect the user

“…Toxic symptoms developed by rats late in pregnancy when fed detoxified rape protein have caused anxiety (Eklund 1973) but the problem appears to have been zinc deficiency exacer bated by the high content of phytin in the concentrate (Shah, Jones, McLaughlan & Beare-Rogers 1976) which can also reduce calcium and magnesium levels (Momcilovic & Shah 1976).…”