Effect of dietary inclusion of goat milk on the bioavailability of zinc and selenium in rats

The effects of dietary inclusion of freeze-dried goat and cow milk on the utilization of zinc and selenium, and on the metabolic fate of zinc, were studied in transected (control) and resected rats (resection of 50% of the distal small intestine). Intestinal resection reduced the apparent digestibility coefficient and zinc retention in the cow milk diet, whereas these biological indices were similar in transected (control) and resected rats with standard (without milk) and goat milk diets. The apparent digestibility coefficient and retention of selenium were not affected by intestinal resection in the animals fed with the three diets studied. In transected (control) and resected rats, the apparent digestibility coefficient and retention of zinc and selenium were higher for the goat milk diet than for the other two diets. Zinc deposits in the organs, expressed as microg/g dry weight were in order of decreasing concentrations: femur, testes, sternum, liver, kidney, heart, spleen, longissimus dorsi muscle and brain. Deposits were greatest with the goat milk diet, followed by the standard diet and were lowest for the rats given the cow milk diet, both for transected (control) and resected animals. We conclude that consumption of the goat milk diet produces a greater bioavailability of zinc and selenium and a greater deposit of zinc in key organs, for both the transected (control) and the resected rats, with respect to the standard diet and the cow milk diet.     

Beneficial effect of goat milk on nutritive utilization of iron and copper in malabsorption syndrome

The search for diets that improve the digestive and metabolic use of iron and copper in malabsorption syndrome led us to study goat milk for particular nutritional characteristics and compare it with cow milk, which is usually supplied. We studied the metabolism of iron and copper in transected rats (control) and in resected rats (resection of 50% of the distal small intestine). The diets used were the standard diet recommended by the American Institute of Nutrition and diets based on goat or cow milk. Intestinal resection reduced the apparent digestibility coefficient (ADC) of iron in the three diets tested. In the transected and resected rats, the ADC of iron was highest with the goat milk diet, followed by the standard diet and lowest with the cow milk diet. The ADC of copper was not affected by intestinal resection in the animals fed the goat milk diet, and was higher than that in the two groups of animals fed the other diets. Intestinal resection reduced the ADC of copper with the standard diet and the cow milk diet. When both groups of animals were fed the goat milk diet, the deposit of iron in the organs was greater than with those fed the cow milk diet and similar to that in those animals given the standard diet. The copper content in the kidneys was lower in the resected than in the transected animals, except in the case of those fed the goat milk diet, in which it was similar to that of the control (transected) rats. This study shows the beneficial effect of goat milk, with respect to cow milk, on the metabolism of iron and copper in control rats, especially those with malabsorption syndrome.     

Digestive utilization of goat and cow milk fat in malabsorption syndrome.

We studied the effects of goat and cow milk fat on the digestive utilization of this nutrient and on some of the biochemical parameters that are related to the metabolisim of lipids, using rats with a resection of 50% of the distal small intestine and control animals (transected). The fat content in all the diets was 10% but the lipid quality was varied: the standard diet was based on olive oil, while the other two diets included fat obtained from lyophilized goat milk and cow milk, respectively. The digestive utilization of the fat was lower in the resected animals than in the transected ones for all three diets studied. In both resected and transected animals. the apparent digestibility coefficient (ADC) of the fat was greater with the standard diet (olive oil) than with diets whose fat content was provided by goat or cow milk. The digestive utilization of the fat was greater in the transected and resected rats receiving a diet of goat's milk (rich in medium-chain triglycerides) than those given a cow-milk-based diet and more closely approached the values obtained for olive oil. The consumption of goat milk reduced levels of cholesterol while levels of triglycerides, HDL, GOT and GPT remained with in the normal ranges, for both transected and resected animals. The advantageous effect of goat milk on the metabolisim of lipids with respect to cow milk suggests that the former should be included in the diet in eases of malabsorption snydrome.     

Calcium-supplemented goat milk does not interfere with iron absorption in rats with anaemia induced by dietary iron depletion

The short-term effects of Ca-supplemented goat or cow milk on the nutritive utilization of Fe were evaluated in a metabolic balance study of rats with nutritional ferropenic anaemia (NFA). Control and Fe-deficient rats were fed for 14 d with goat or cow milk diets containing high-Ca content (10,000 mg/kg diet). The consumption of diets containing high levels of Ca for 14 d had no adverse effects on Fe absorption when the goat milk-based diet was provided, whereas for the cow milk-based diet, there was a significant fall in the apparent digestibility coefficient (ADC) of Fe. Moreover, the ADC and Fe retention/intake ratio (R/I) were higher in the anaemic rats fed the goat milk diet than among those fed the cow milk diet. These results suggest that despite a high dietary Ca content, goat milk minimizes Ca–Fe interactions and has no adverse effects on Fe absorption in rats with NFA.     

Calcium‐enriched goat milk,in comparison with similarly enriched cow milk,favours magnesium bioavailability in rats with nutritional ferropenic anaemia

BACKGROUND: The effects of dietary consumption of goat or cow milk, normal or enriched with calcium (Ca), on magnesium (Mg) bioavailability was evaluated in rats with nutritional ferropenic anaemia. Control and iron‐deficient rats were fed for 14 days with iron‐normal diets containing either normal (5000 mg kg^?1 diet) or high (10 000 mg kg^?1 diet) Ca content. RESULTS: The results shown that the goat milk diet gave the best results for digestive and metabolic utilization of Mg, both among the anaemic and the control group, with respect to the cow milk and standard diets. The most noteworthy result of Ca enrichment on the nutritive utilization of Mg is that it is less prejudicial in this respect when supplemented via goat milk than with cow milk or the standard diet. CONCLUSION: The results demonstrate the beneficial effects of the goat milk, normal or with double Ca, on the nutritional utilization of Mg; therefore the consumption of this type of milk for people with nutritional ferropenic anaemia can be recommended. Copyright © 2007 Society of Chemical Industry     

Effect of calcium-supplemented goat or cow milk on zinc status in rats with nutritional ferropenic anaemia

The effects of goat- or cow-milk-based diets, whether normal or supplemented with calcium (5 or 10 g kg^?1 Ca, respectively), on the nutritive utilization of Zn and its deposition in organs, were evaluated in rats with and without nutritional ferropenic anaemia (NFA). The digestive and metabolic utilization of Zn in anaemic and control groups was higher for rats on the goat milk diet than those on the cow milk diet. The most noteworthy result is that Ca supplementation in the diet improved Zn metabolism in all experimental groups, but especially in anaemic rats fed the goat milk diet. This fact is reflected in the higher levels of Zn deposition found with the goat milk diet. It appears that goat milk, especially when supplemented with Ca, had beneficial effects on nutritive utilization of Zn and Zn deposition in target organs in both control rats and, especially, rats with NFA.     

Calcium-enriched goats' milk aids recovery of iron status better than calcium-enriched cows' milk, in rats with nutritional ferropenic anaemia

Ca-Fe interactions are known, but no studies are available about the effects of Ca-enriched goat or cow milk on Fe status in nutritional ferropenic anaemia (NFA). To examine this matter, control and Fe-deficient rats were fed for 14 d with goat or cow milk diets containing either normal or high Ca content (5000 or 10,000 mg/kg diet), and different indices and parameters related to iron status were measured. The apparent digestibility coefficient (ADC) and the Fe retention/intake (R/I) ratio were higher in control and anaemic rats fed goat milk diet (G diet), despite high-Ca content. Ca enrichment decreased Fe stores in liver and sternum in anaemic rats fed cow milk diet (C diet), however G diet did not modify Fe content in the organs studied in control and anaemic rats. In anaemic rats, Ca-supplementation decreased haematocrit, but platelets and serum Fe were not affected, however, in control rats platelets increased except for Ca-enriched G diet, this fact reveals that Ca-Fe interaction is minimized with G diet. Serum ferritin was always higher in rats fed G vs. C diet, both in control and anaemic rats fed either normal or Ca-enriched diets. Ca-supplementation decreased ferritin levels in control and anaemic rats fed C diet and also, though to a lesser extent, in those given the G diet. This indicates that with this G diet there is a better recovery of body Fe stores in anaemic rats, despite Ca-supplementation. In this study it is noteworthy that despite high Ca content, a goat milk diet resulted in minimal Ca-Fe interactions and did not adversely affect Fe status in rats with NFA.     

Biological value of protein from raw fish and canned fish

The authors evaluated the nutritive value of protein from 4 kinds of raw fish (herring, cod, mackerel, sprat) and its preserves. Experiments were made on rats fed the diets containing fish protein (8-10% of the total diet). Experiments included the determination of apparent and genuine digestibility, net protein utilization, and net dietary protein caloric value. Evidence was obtained that protein from fish and its preserves is characterized by high digestibility coefficient as compared with casein and egg powder. The highest net protein utilization was noted in animal groups fed the diet containing protein from raw fish. Protein assimilability from fish preserves was on the average 15% lower than that from raw fish.     

True ileal amino acid digestibility of goat and cow milk infant formulas

Goat milk is used as an alternative to cow milk for the production of infant formulas. However, little is known about the protein quality and, specifically, about the digestible AA pattern of goat milk formulas compared with their cow milk counterparts. In this study, the true ileal AA digestibility of a goat milk infant formula was compared with a premium cow milk infant formula. The 3-wk-old piglet was used as a model for the 3-mo-old infant. Both milk formulas were prepared as described by the manufacturer, with titanium dioxide added as an indigestible marker. The formulas were fed to the piglets over a 2-wk trial period. Digesta from the terminal ileum were collected post euthanasia and analyzed for AA content, along with samples of the formulas. True AA digestibility was determined after correcting for endogenous AA loss at the terminal ileum of pigs fed an enzyme-hydrolyzed casein-based diet, followed by ultrafiltration (5,000 Da) of the digesta. Total urine and feces collection was also undertaken to determine the nitrogen retention from the diets. The true ileal AA digestibility was similar between the goat and cow milk infant formulas for all AA except Gly and Trp. There was no significant difference in the nitrogen retention of piglets fed the two different formulas. The goat milk infant formula and the premium cow milk infant formula were similar in terms of protein quality.     

Bioavailability of nutrients in rats fed on edible seaweeds,Nori (Porphyra tenera) and Wakame (Undaria pinnatifida), as a source of dietary fibre

A comparative study of the influence of two edible seaweeds, Nori (Porphyra tenera) and Wakame (Undaria pinnatifida), on dietary nutritive utilization was performed. Male adult Wistar rats were fed, for 2 weeks, diets containing Nori, Wakame or cellulose as source of dietary fibre. All diets contained similar amounts of dietary fibre (5%), protein (14%) and ash (5%). Intake, body weight gain, food efficiency (weight gain/food intake), apparent digestibility and retention coefficients for protein, fat, and minerals (calcium, iron, magnesium, zinc, sodium, and potassium) were evaluated. The addition of Wakame or Nori did not affect the gain in body weight of rats or food efficiency. Fresh and dry stool weights were higher in rats fed seaweeds than in the control group. Seaweed-fed animals showed significantly lower apparent digestibilities of protein and fat but absorbed nitrogen was more effectively used by animals. Apparent digestibility and retention coefficients for calcium, magnesium, zinc, iron, sodium and potassium were lower for seaweed-fed rats, and showed lower values for Wakame than Nori. The seaweeds could be a good source of dietary fibre in diet but they may modify digestibility of dietary protein and minerals.     

Influence of dietary fat on nutritive utilization of protein in intestinally resected rats

The effects of different types of dietary fat on the digestive and metabolic utilization of protein were studied in rats with 50% resection of the distal small intestine and in sham-operated controls one month after surgery. The digestive utilization of protein was not significantly affected in intact animals when olive oil was replaced by butter as the dietary source of fat. In resected rats given either type of diet the apparent digestibility coefficient of protein declined significantly in comparison to intact controls. Intestinal resection decreased the retention of nitrogen significantly in rats given olive oil. The replacement of 2/3 of the dietary supply of olive oil with 1/3 medium chain triglycerides and 1/3 sunflower seed oil improved the metabolic utilization of protein in comparison to resected rats fed olive oil or butter as the only source of dietary fat. However, the addition of ursodeoxycholic acid to the diet containing equal parts of olive oil, medium chain triglycerides and sunflower seed oil failed to improve the metabolic utilization of protein in comparison to that seen in rats given olive oil only. Serum concentrations of total protein, urea and creatinine, albeit with slight changes in the first, remained within normal limits. Despite the lower retention of nitrogen in resected rats, these animals maintained homeostasis without resorting to muscular protein.     

Goat milk feeding causes an increase in biliary secretion of cholesterol and a decrease in plasma cholesterol levels in rats

The hypocholesterolemic effect of goat milk with respect to cow milk observed in a previous study led us to examine the influence of goat and cow milk in the diet on certain aspects of biliary physiology in normal rats. The fat content in all diets was 10% but the lipid quality was varied: the standard diet was based on virgin olive oil, and the other 2 diets included fat obtained from lyophilized cow milk and goat milk. We characterized the bile secretion, including biliary phospholipid, cholesterol, and bile acid outputs, the interrelation between bile acids and bile lipids, and the lithogenic index. The consumption of goat milk in the diet, compared with that of cow milk, caused an increase in the biliary secretion of cholesterol together with a decrease in plasma cholesterol concentration, whereas values for bile phospholipids, biliary acid concentrations, and the lithogenic index remained normal. Moreover, consumption of this type of milk decreased plasma triglyceride concentration and therefore had a positive effect, similar to that of olive oil (standard diet), on the lipid metabolism; hence, it may be recommended for consumption by the general population.     

The effect of formulated goats' milk on calcium bioavailability in male growing rats

BACKGROUND: There are two main proteins in milk; whey and casein. Casein contains casein phosphopeptides (CPP), which are released on digestion of the milk. These may increase calcium solubility by binding calcium in the small intestine. Thus increasing casein in the diet may help to stimulate bioavailability of calcium and increase bone density. The present study tested this hypothesis in growing male rats fed diets containing three different concentrations of casein from goat milk. RESULTS: Rats fed the diet containing no casein had significantly lower calcium absorption when compared to rats fed the diets that contained 80% and 57% of goat milk protein as casein; however, no significant difference was observed between rats fed diets with 80% and 57% casein. The varying amounts of casein had no effect on mineral uptake or retention in the femur. Biomechanical testing and mineral analysis of the femurs showed no differences between diet groups. The mechanism to explain this lack of retention remains unclear. CONCLUSION: The diets containing 80% and 57% of goat milk protein as casein delivered increased calcium absorption compared to the diet containing no casein, suggesting a minimum level of casein is needed to optimize calcium absorption from goat milk. Copyright © 2009 Society of Chemical Industry     

Egg yolk protein and egg yolk phosvitin inhibit calcium, magnesium, and iron absorptions in rats

ABSTRACT:  Egg yolk decreases the absorption of iron. The effects of egg yolk protein and egg yolk phosvitin on the absorption of calcium, magnesium, and iron were investigated by in vivo studies. Male Wistar rats were fed purified diets containing casein, soy protein, or egg yolk protein for 14 d. The apparent absorptions of calcium, magnesium, and iron in the rats fed the yolk protein-based diet were lower than those in rats fed the casein- and soy protein-based diets. The apparent phosphorus absorption and the apparent protein digestibility in the yolk protein group were lower than those in the casein and soy protein groups. In the feces of the yolk protein group, serine comprised more than 30% of the amino acids. The addition of egg yolk phosvitin to the casein diets at levels of 1% and 2% (w/w) produced effects on calcium and magnesium absorptions similar to those produced by the diet containing yolk protein. The tricine sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) pattern suggested that phosphopeptide fragments having molecular masses of 28, 22, and 15 kDa were evident in the contents of the small intestine of the rats fed phosvitin diets. These results indicate that yolk protein, when compared with casein and soy protein, decreases calcium and magnesium absorption via the resistance of phosvitin to proteolytic action.     

Goat milk during iron repletion improves bone turnover impaired by severe iron deficiency

The effect of goat or cow milk-based diets, with either normal Fe content or an Fe overload, on bone turnover and the mineralization process was studied in control and anemic rats during chronic Fe repletion. One hundred eighty male Wistar rats were studied during a pre-experimental period of 40 d in which they were randomly divided into 2 groups, a control group receiving the AIN-93G diet with normal Fe content (45 mg/kg of diet) and the Fe-deficient group receiving the AIN-93G diet with low Fe content (5 mg/kg of diet) for 40 d. After the pre-experimental period, the rats were fed for 10, 30, or 50 d with goat or cow milk-based diets with a normal Fe content (45 mg/kg of diet) or an Fe overload (450 mg/kg of diet). In anemic rats, goat milk with normal Fe content increased levels of the biomarker of bone formation N-terminal propeptides of type I procollagen and diminished parathyroid hormone levels after only 10 d of supplying this diet, indicating the beginning of restoration of the bone demineralization induced by the anemia, which was not observed with cow milk. After 30 d of supplying the milk-based diets with normal Fe content or an Fe overload, biomarkers of bone formation and bone resorption were not different between control and anemic rats, indicating that the bone demineralization induced by the Fe-deficiency anemia had recovered, although the process of stabilization of bone turnover began earlier in the animals fed goat milk. In addition, a higher Ca deposit was observed in femur, which positively affects bone mineralization, as well as an increase of Fe in sternum, which indicates that the hematopoietic process essentially recovered earlier on the goat milk diet compared with the cow milk diet.     

Factors Affecting the Protein Quality of Yogurt and Acidophilus Milk

The apparent protein digestibility in vivo, the protein digestibility in vitro, the net protein ratio, and computed protein efficiency ratio were used to assess the protein quality of yogurt and acidophilus milk as affected by heat treatment, direct acidification, addition of culture, or fermentation. Rats fed diets containing either heated mix or yogurt tended to eat more and gain more weight than rats fed diets containing either unheated mix or the acidified yogurt. Feed efficiency was also significantly higher for rats fed heated mix and yogurt. The apparent protein digestibility in vivo was significantly higher in yogurt diet than in the unheated yogurt mix diet. The net protein ratio of the yogurt diet was significantly higher than that of either the unheated mix or the acidified yogurt but not significantly different from the heated mix. The computed protein efficiency ratio values were also increased with both heating and fermentation. The direct acidified yogurt had a significantly lower net protein ratio and lower computed protein efficiency ratio than the fermented yogurt. Rats fed either sweet acidophilus (unfermented) or acidophilus milk exhibited a significantly higher protein digestibility than rats fed heated milk, indicating that the lactic culture may have a direct effect on protein digestibility. Despite their increased protein digestibilities, the acidophilus products did not display any significant increase in net protein ratio or computed protein efficiency ratio.     

Improvement in food intake and nutritive utilization of protein from Lupinus albus var. multolupa protein isolates supplemented with ascorbic acid

The protein quality of protein isolates from lupin (LPI) (Lupinus albus var. multolupa), prepared by isoelectric precipitation, was assessed by chemical analysis of protein and amino acids and biological analysis of digestive and metabolic utilization of protein by growing rats. The animals were fed isonitrogenous and isocaloric diets adjusted to meet their nutrient requirements, in which lupin protein isolate was the only protein source, complemented with 0.5% methionine. Different LPIs were prepared with addition, or not, of ascorbic acid as antioxidant. Protein isolates had a protein content of 87.8–98.1%. Manganese content of protein isolates was reduced by 72.8–89.5% compared to the raw seed flour. Results from in vivo experiments showed that addition of 0.5% ascorbic acid to LPI incorporated into diets led to a 82.8% increase in daily food intake, when compared to the non-supplemented LPI, reaching similar values to those obtained with a casein–methionine control diet. Digestive and metabolic utilization of protein from LPI, assessed by nitrogen absorption or apparent digestibility coefficient, and by nitrogen balance or percentage of retained to absorbed nitrogen, respectively, was high, when the dietary intake of animals fed the LPI diets was adequate after addition of 0.5% ascorbic acid, although slightly inferior to the values obtained with a casein–methionine control diet. The high nutritive utilization of protein was reflected in excellent growth and nutritional indices assayed. In conclusion, ascorbic acid supplementation led to an improvement in the palatability of the LPI diets and, therefore, in daily food intake, which was reflected in a higher nutritive utilization of protein and improvement in weight gain and the food transformation index.     

Goat milk consumption modulates liver divalent metal transporter 1 (DMT1) expression and serum hepcidin during Fe repletion in Fe-deficiency anemia

Iron deficiency is the most prevalent micronutrient deficiency worldwide. In spite of the crucial role of hepatocyte divalent metal transporter 1 (DMT1) and hepcidin in Fe metabolism, to date, no studies have directly tested the role of these proteins in liver Fe metabolism during Fe repletion after induced Fe-deficiency anemia. Therefore, the aim of the current study was to assess the effect of goat or cow milk-based diets on Fe metabolism in one of the main body storage organs, the liver, during the course of Fe repletion with goat or cow milk-based diets in anemic rats. Animals were placed on a preexperimental period of 40 d, a control group receiving a normal-Fe diet and the Fe-deficient group receiving a low-Fe diet (5 mg of Fe/kg of diet). Rats were fed for 30 d with goat or cow milk-based diets with normal Fe content (45 mg of Fe/kg of diet). The hematological parameters, serum hepcidin, hepatosomatic index, liver Fe content, and liver DMT1 expression were determined. During the recovery of the anemia with milk-based diets, the restoration of liver Fe content and hematological parameters, especially with goat milk, increased the red blood cell count, favoring the oxygen supply and weight gain. Moreover, goat milk consumption potentiates liver DMT1 expression, enhancing Fe metabolism and storage. In addition, the increase in serum hepcidin in anemic rats observed in the current study also explains and supports the higher liver Fe content after supplying goat milk, because it blocks the liberation of Fe from hepatocytes, increasing its storage in liver.     

Influence of intestinal resection and type of diet on the digestive and metabolic utilization of fats in rats

The effects of the quality of dietary fat, and the influence of ursodeoxycholic acid, an exogenous bile acid, on the digestive and metabolic utilization of fat were studied in rats in which 50% of the distal small intestine was resected. The fat content of the diets was quantitatively equivalent (4%), and differed only in the type of fat: olive oil (diet A) or 1/3 medium chain triglycerides (MCT), 1/3 sunflower oil and 1/3 olive oil (diet B). The removal of 50% of the distal small intestine led to a highly significant decline in the digestive utilization of fat (ADC) in animals given diet A. Rats fed diet B showed an increase in ADC to values approaching those seen in control animals. The addition of ursodeoxycholic acid to diet B failed to cause a further rise in the ADC of fat. After intestinal resection, serum levels of triglycerides and cholesterol fell more markedly in animals given diet A than in the diet B group, while the addition of ursodeoxycholic acid to diet B led to no further change. Serum lipid levels showed no significant influence of intestinal resection, but did accurately reflect the differences in fat composition between the two types of diet tested.     

Effects of raw pea flour on nutrient digestibility and immune responses in the preruminant calf.

Two milk substitute diets for which the protein was provided either exclusively by skim milk powder (control) or partially (34%) by dehulled raw pea flour were given for 2 and 4 wk, respectively, to five preruminant calves, each fitted with a reentrant ileocecal cannula. Ileal apparent digestibility was lower with the pea diet during wk 1 than with the control diet. Four of the cannulated calves exhibited significant intolerance to the pea diet, resulting in lower digestibility during wk 4. In contrast, fecal digestibility of the pea diet, measured in four additional calves without reentrant cannulas, did not significantly decrease between wk 1 and 4. The AA composition of ileal digesta from the first group of calves did not vary greatly, suggesting that the differences observed in their apparent digestibility of proteins were due mainly to changes in the loss of endogenous proteins. However, pea legumin survived digestion in the small intestine in amounts generally equivalent to 1 to 3% of intake. Most of that undigested fraction was smaller than the native legumin: 40 to 200 kDa instead of 360 kDa. Also, a 45-kDa fragment was detected in the urine. Increased intestinal permeability could have favored the development of the high systemic anti-pea antibody titers that were observed in all of the calves.