CSIRO PUBLISHING Animal Production Science, 2019, 59, 1689–1695 https://doi.org/10.1071/AN17862 Dietary calcium supplementation affects nutrient digestibility and antler-production performance during the antler-velvet growth period of male sika deer Weili Sun A,*, Haiping Zhao A,*, Kun Bao A, Chunyi Li A and Guangyu Li A,B AInstitute of Special Animal and Plant Sciences, Chinese Academy of Agriculture Sciences, Jilin Provincial Key Laboratory for Molecular Biology of Special Economic Animals, No. 4899, Juye Street, Jingyue District, Changchun City, Jilin Province 130112, China. BCorresponding author. Email: [email protected] Abstract. Effects of calcium (Ca) supplementation on nutrient digestibility, physiochemical characteristics and antler growth in farmed male sika deer were investigated. Eighteen sika deer (6 years old, 105.50 Æ 5.05 kg) were assigned into the following three treatments where they had ad libitum access to water for 90 days: (1) control (C), basal diet containing 0.5% Ca; (2) Ca1.10, basal diet supplemented with 0.6% Ca; and (3) Ca1.70, basal diet supplemented with 1.2% Ca. The basal diet contained 0.50% Ca and 0.34% phosphorus (P). Each group consisted of the same ratio of Ca to P (provided as CaCO3 and CaHPO4). The results showed that the digestibility of dry matter (DM) and crude protein in the Ca1.70 group was lower than in the other two groups. The digestibilities of Ca, P and neutral detergent fibre in the Ca1.10 group were higher than those in the C group and Ca1.70 group (P < 0.05). Concentrations of Ca and P in faeces increased with an increasing supplementation level of Ca and the highest concentrations were observed in the Ca1.70 group (P < 0.05). There were no differences in the concentrations of parathyroid hormone, alkaline phosphatase and osteocalcin among the treatments. Testosterone and oestradiol concentrations of the Ca1.7 group were higher than those of the C and Ca1.10 groups (P < 0.05). Average daily gainsof freshantler weightand dryantler weight of the groups Ca1.10 and Ca1.70 weregreater than thoseof the C (P < 0.05). Fresh and dry antler yields of the Ca1.10 group were higher than those of the other groups (P < 0.05). In conclusion, optimal level of Ca supplement was found to be total Ca concentration of 1.10–1.70%, on the basis of DM, which significantly increased feed digestibility and antler daily gain for the 6-year-old sika deer. Additional keywords: antler growth, Ca, P. Received 11 December 2017, accepted 29 October 2018, published online 25 January 2019 Introduction the assessment of the Ca value of feeds can be addressed. Velvet antler is a precious animal-based traditional Chinese Calcium is absorbed from the diet according to need by a medicine. Previous studies on humans and rats have hormonally regulated process in the small intestine (Schneider convincingly shown the health benefits of deer velvet-antler 1985; Bronner 1987), up to limits set by the diet and by the net supplements (Wu et al. 2013). Antlers of deer arguably are movement of Ca into or out of the skeleton. the fastest and most robust bone development organs in the Growth of deer antlers requires large amounts of P and Ca animal kingdom. An antler is composed of ~50% minerals and in a short period (less than 90 days). It has been calculated out of these, 45% is calcium (Ca), and 19% phosphorus (P) that a pair of red deer antlers weighing 13 kg and grown for (Chapman 1975). Composition explained a mean variability 130 days corresponds to an average daily increase of 100 g of of 77% in antler length and weight. Bodyweight and size, in bone (Chapman 1975). The source of these large amounts of turn, influenced mineral composition (Landete-Castillejos et al. minerals used for antler growth has not clearly been determined; 2007). Animal skeletons not only provide strong framework namely, whether they are obtained directly from food or, in for supporting muscles and protect delicate organs and tissues, part, at the expense of other parts of the body, or both. Indeed, a such as bone marrow, but also form joints to allow movement, similar picture was found in the ribs, metacarpus, metatarsus and are malleable to allow growth. Furthermore, the skeletal and tibia of mule deer, where it was found that there was a cyclic reserve of Ca actively supports Ca homeostasis (Bain and mobilisation of cortical bone minerals during antler growth, Watkins 1993). Calcium metabolism must be described before despite high quantities of minerals in the food that could be *These authors contributed equally to this work. Journal compilation Ó CSIRO 2019 Open Access CC BY-NC-ND www.publish.csiro.au/journals/an 1690 Animal Production Science W. Sun et al. accessed (Brown 1990; Grasman and Hellgren 1993). During Table 1. Composition and nutritive concentrations (dry-matter basis, antler growth, there was a marked increase in resorption foci and %) of basal diets (control, Ca 1.10 and Ca 1.70) a decrease in bone density and the reverse occurred on cessation of antler growth, so that the cortical bone soon returned to a Parameter Concentration normal, stable configuration. Before the rutting season, during Control Ca 1.10 Ca 1.70 fi the tness-recovery period in July and August, the process Corn 22.50 18.76 15.40 reverses and bone mineral density is restored. In mule deer, Soybean meal 19.50 20.00 21.00 mineral resorption is highest in the ribs, reaching 23% during the Distillers dried grains with solubles 7.50 7.00 5.50 middle period of antler growth, and falling to less than 3% by the Corn germ 6.00 7.50 8.00 time antler growth is completed (Chapman 1975). Resorption Alfalfa hay 40.00 40.00 40.00 was greatest during the mid-period of antler growth, reaching Syrup 3.00 3.00 3.00 23% for ribs, 13% for the metacarpus and 10% for the metatarsus Salt 0.50 0.50 0.50 A (Banks et al.1968b). After antler growth was completed, the Premix 1.00 1.00 1.00 resorption in the ribs fell to less than 3%. This cyclical, CaHPO4 0.00 2.00 5.00 CaCO 0.00 0.24 0.60 physiological osteoporosis was confirmed by measurement of 3 Total 100.00 100.00 100.00 the density of the bone, and contents of ash, Ca, magnesium (Mg) and P (Banks et al. 1968; Hillman et al. 1973). Recently, Measured nutrient concentration scientists have aimed to identify the genes and pathways that Dry matter (DM) 91.19 90.36 90.77 significantly alter their expression levels when osteoporosis Crude protein (CP) 18.61 18.75 18.60 Ether extract (EE) 2.35 2.42 2.41 develops as well as in the reverse phase in the deer skeleton Ca 0.49 1.07 1.77 during the antler growth cycle of deer (Borsy et al. 2009; Stéger Total P 0.34 0.74 1.22 et al. 2010). These genes include IGSF4, FABP3, FABP4, Ratio of Ca : P 1.45 1.45 1.45 FKBP2, TIMP2, TMSB4X, TRIB, and members of the Wnt Metabolisable energy (ME) (MJ/kg) 17.48 17.02 16.98 signalling. Neutral detergent fibre (NDF) 46.45 47.01 45.22 An improvement in antler formation was noted in deer that Acid detergent fibre (ADF) 21.92 21.90 23.44 were fed Ca and P supplements as compared with the deer that AOne kilogram of premix contained the following: MgSO 16.7 g, CuSO were on the Ca- and P-deficient diets (Magruder et al. 1957). 4 4 2.7 g, MnSO4·H2O 6.3 g, ZnSO4·H2O 6.3 g, FeSO4·H2O 8.0 g, Na2SeO3 The Ca-deficient diet was again observed to limit antler growth 3.4 g, Vitamins 5.3 g (VA 2484 IU, VD3500 IU, VE 1.0 IU, VK3 0.23 mg, when compared with with Ca-supplemented diet, but the effect VB1 0.1 mg, VB2 0.7 mg, VB2 0.01 mg, folic acid 0.023 mg, nicotinamide was not as marked as in the other deficiencies. Studies have 0.002 mg). reported the suitable concentration of P in white-tail deer and red deer (French et al. 1956; Muir et al. 1987). However, the Experiment design effects of suitable concentration of Ca and P on the deer nutrient digestibility and the velvet antler production remain The experiments were started from the hard antler button casting fi fi to be demonstrated in Chinese sika deer. The aim of the present and nished when antlers grew to the nal stage (but still in study was to evaluate the effects of dietary Ca on nutrient velvet, ~90 days). Antler removal day was determined by the digestibility, blood biochemical parameters and production farm professional technicians. The digestion trials were fi performance of velvet antlers for the farmed male sika deer conducted three times in the end of rst month, second month during velvet-antler growth period. and last month, and lasted for 4 days each time. Faecal samples were collected individually in the same time during the period of digestion trials. The total velvet-antler growth experiment Materials and methods lasted for 90 days. The digestibility (%) of dry matter (DM), crude protein (CP), neutral detergent fibre (NDF), acid detergent The experiment was conducted under the animal care and user fi guidelines at the Antler Deer Farm of the Institute of Special bre (ADF), Ca and P were determined using the method of Animal and Plant Research, Chinese Academy of Agricultural ash insoluble in 2 mol/L HCl.