Composition, Structure, and Digestive Dynamics of Milk From Different Species—A Review

Abstract

Background: The traditional dairy-cattle-based industry is becoming increasingly diversified with milk and milk products from non-cattle dairy species. The interest in non-cattle milks has increased because there have been several anecdotal reports about the nutritional benefits of these milks and reports both of individuals tolerating and digesting some non-cattle milks better than cattle milk and of certain characteristics that non-cattle milks are thought to share in common with human milk. Thus, non-cattle milks are considered to have potential applications in infant, children, and elderly nutrition for the development of specialized products with better nutritional profiles. However, there is very little scientific information and understanding about the digestion behavior of non-cattle milks. Scope and Approach: The general properties of some non-cattle milks, in comparison with human and cattle milks, particularly focusing on their protein profile, fat composition, hypoallergenic potential, and digestibility, are reviewed. The coagulation behaviors of different milks in the stomach and their impact on the rates of protein and fat digestion are reviewed in detail. Key findings and Conclusions: Milk from different species vary in composition, structure, and physicochemical properties. This may be a key factor in their different digestion behaviors. The curds formed in the stomach during the gastric digestion of some non-cattle milks are considered to be relatively softer than those formed from cattle milk, which is thought to contribute to the degree to which non-cattle milks can be easily digested or tolerated. The rates of protein and fat delivery to the small intestine are likely to be a function of the macro- and micro-structure of the curd formed in the stomach, which in turn is affected by factors such as casein composition, fat globule and casein micelle size distribution, and protein-to-fat ratio. However, as no information on the coagulation behavior of non-cattle milks in the human stomach is available, in-depth scientific studies are needed in order to understand the impact of compositional and structural differences on the digestive dynamics of milk from different species.

Ruminant Milk-Derived Extracellular Vesicles: A Nutritional and Therapeutic Opportunity?

“…Species-dependent differences are evident in the macromolecule composition (fat, sugars, etc. ), vitamin and mineral content, and how it is digested after consumption [ 30 , 273 , 274 ]. Furthermore, milk has differences in its molecular composition and conservation of function that influence its specific biological value depending on the species of origin.…”

A Comparative Review of the Cell Biology, Biochemistry, and Genetics of Lactose Synthesis

“…In fact, the concentration of lactose in the milk of different primates is consistently high (61 to 89 mg/ ml) and accounts for one-to two-thirds of total milk energy [5]. In a similar way, lactose in bovine milk (44 to 56 mg/ ml) provides approximately 30% of the calories required by newborn calves [1,6]. Milk produced by rodents has a lower content of lactose, ranging from 24 to 28 mg/ml in mice, and 11 to 41 mg/ml in rats [7].…”

“…Data for fat and lactose content in the milk of the human, cow, goat, mouse, rat, dog, minipig are presented as the mean of published ranges. Tammar wallaby: Fat (40 mg/ ml) was measured at 26 weeks of lactation and lactose (39 mg/ml) between 13 and 34 weeks of lactation [25,140]; Florida manatee: Fat (190 mg/ml) and lactose (not detected) at 30 weeks and at 2 years of lactation [9]; Human: fat (28-44 mg/ml) and lactose (61-79 mg/ml) between 40 and 180 days postpartum [5]; Lemur: fat (18 mg/ml) and lactose (81 mg/ml) at 72 days postpartum [5]; Cow: fat (33-54 mg/ ml) and lactose (44-56 mg/ml) during mid-lactation [6]; Horse: fat (12.1 mg/ml, range 50-200) and lactose (63.7 mg/ml, range 58-70) during mid-lactation [141]; Goat: fat (40 mg/ml) and lactose (32-50 mg/ml) during mid-lactation [6]; Mouse: fat (190-220 mg/ ml) and lactose (24-28 mg/ml) in mature milk samples [7]; Rat: fat (140-159 mg/ml) and lactose (11-41 mg/ml) in mature milk samples [7]; Rabbit: fat (152 mg/ml) and lactose (18 mg/ml) in mature milk samples [7]; Dog: fat (24-134 mg/ml) and lactose (29-40 mg/ml) in mature milk samples [7]; (mini)Pig: fat (77-100 mg/ml) and lactose (43-56 mg/ml) in mature milk samples [7]; Subantarctic fur seal: fat (510 mg/ml) and lactose (not detected) in mid-lactation samples [12]; Polar bear: fat (278 mg/ml) and carbohydrate (26 mg/ml) in yearlings mid-lactation sample [142] lactose is considerably higher than that found in human or bovine milk. For example, the ratio of oligosaccharides to free lactose ranges from 7:1 for the striped skunk and 5:1 for mink, to 31:1 for polar bears and 52:1 for the Japanese bear [18,20].…”

Bovine Colostrum and Its Potential for Human Health and Nutrition

“…Together, the existing evidence in support of colostrum suggests that there is potential for colostrum to have a significant role in supporting human health as well. While there are other studies which have begun to look at colostrum from other animals (24)(25)(26)(27), this review explores the current knowledge on the bovine colostrum in the context of nutrition, its bioactive components, and its potential for human health and nutrition.…”