The objective of this study was to determine the major nutrient composition of Indian rhinoceros milk ( Rhinoceros unicornis) over the first 13 mo of an 18-mo lactation period and to compare the results to those of previous studies on rhinoceros, African elephant ( Loxodonta africana), and horse milk ( Equus ferus caballus). The following parameters were measured: dry matter (DM), crude ash (ASH), crude protein (CP), ether extract (EE), nitrogen-free extract (NFE; calculated), lactose, calcium (Ca), phosphorus (P), magnesium (Mg), fatty acids (FAs), and gross energy (GE). DM, ASH, CP, and EE were determined with a proximate analysis, lactose with infrared spectroscopy and an enzymatic method, minerals with an autoanalyzer, FA with gas chromatography, and GE with bomb calorimetry. Milk samples were collected from two Indian rhinoceros cows from Zoo Basel. Rhino A gave birth to her third calf on 10 September 2012; three samples were collected and analyzed (colostrum, milk 1 wk and 2 wk postpartum). Rhino B gave birth to her eighth calf on 05 October 2013; samples were collected and 15 were chosen for the analyses (from colostrum to 13 mo postpartum). The composition of rhino B's colostrum was 13.8% DM (wet-weight basis), 4.8% ASH, 61.8% CP, 0.7% EE, 32.6% NFE, 26.7% lactose, 0.59% Ca, 0.54% P, 0.2% Mg (DM basis), and 20.3 MJ GE/kg DM. Rhino B's sample collected 13 mo postpartum averaged 8.0% DM (wet-weight basis), 3.6% ASH, 16.3% CP, 1.8% EE, 78.3% NFE, 84.7% lactose, 0.54% Ca, 0.48% P, 0.09% Mg (on DM basis), and 17.43 MJ GE/kg DM. The main FAs in rhino B's and rhino A's samples were C10 : 0, C12 : 0, C16 : 0, C18 : 1n9c, and C18 : 2n6c. Milk of the Indian rhinoceros is low in fat and protein but high in lactose, which is comparable to the milk composition of other rhinoceros species and horses, but not African elephants.
Keywords: Changes over lactation; Indian rhinoceros (Rhinoceros unicornis); colostrum; hindgut fermenters; milk; milk composition.