[Ectopic osteogenesis of bone marrow stromal cells induced by bone morphogenetic protein].

OBJECTIVE: To investigate the ectopic osteogenesis of bone marrow stromal cells (MSC) induced by bone morphogenetic protein(BMP) in vitro and in vivo, providing the experimental evidence for making an artificial bone with its own capacity of bone formation. METHODS: MSC were separated and cultured from bone marrow of Wistar rats, MSC were co-cultured with BMP in vitro (cultured in plate and diffuse chamber). Artificial coral hydroxyapatites (CHA) with MSC and BMP were implanted into dorsal muscles of Wistar rats, their bone formation were observed by morphological examination, histochemistry and immunohistochemistry. RESULTS: Only cartilaginous matrix were produced by MSC in vitro (cultured in plate and diffuse chamber), and both cartilaginous and bone matrix production within the combined grafts were seen. The bone formation of experimental groups (CHA + BMP + MSC) was stronger than that of control A(CHA + MSC) and control B(CHA). CONCLUSION: It may be possible to produce an artificial bone with its own capacity of bone formation by combined graft (CHA + BMP + MSC). There may be multiple factors as well as BMP inducing bone formation both in the whole body and the location of the implantation. Further research on these factors will have the significance for making the ideal artificial bone.

Effect of strategic feed supplementation on productive and reproductive performance in yak cows.

A total of 2230 yak cows (5-13 years of age) in two populations with different milking systems were investigated. One population had a system of milking once a day (MOD), and the other population twice a day (MTD). The average milk yield of MOD cows was 0.7 +/- 0.2 kg/day within a milking period of 109 +/- 9 days. This compared with an average of 1.24 +/- 0.3 kg/day in 127 +/- 6 days in MTD yaks (p < 0.01). The cows showed a calving rate of 71% under the MOD system and 51.4% under the MTD system. Three farms with a total of 104 MTD cows between six and 12 years of age were used to provide three different feeding groups. The groups were fed with, or without oat hay or highland barley straw in amounts of 1-1.5 kg/head/day from December to April. The three farms were designated as Farm I, Farm II, and Farm III. Farm I had 41 cows with body weight of 230 +/- 67 kg each for grazing with no supplement (GNS). Farm II had 30 animals with body weight of 216 +/- 28 kg each for grazing + oat hay (GOH). Farm III had 33 animals body weight of 221 +/- 34 kg each for grazing + highland barely straw (GBS). The calving rates of the cows in GOH and GBS were 23 and 19% higher, respectively, than GNS cows (p < 0.01), and the highest rate reached 76.7% in GOH. The live weight loss of the cows in GNS was considerably higher (p < 0.01) than in the two other groups. Ten GOH cows and 12 GNS cows were used to collect milk samples for measuring the progesterone concentration using RIA kits provided by IAEA/FAO: Milk was sampled every five days from calving until 90 days postpartum. In the unsupplemented group, milk progesterone (P4) levels suggested that cows had started cyclic ovarian activity by 40 days postpartum, whereas only 25% had been observed in estrus. In the supplemented group, 80% of cows had started cyclic ovarian activity by the same time and 70% had been seen in estrus. Two types of cyclic activity in terms of progesterone changed were found. With Type I (normal), 50 and 80% of cows from GNS and GOH, respectively, had cyclic changes of P4 in milk at 40 days postpartum. With Type II, the P4 levels in the milk remained 0.89 ng/ml until 90 days postpartum. A total of 46 grazing cows between five and 13 years of age (body weight 214 +/- 68 kg) was used to collect blood samples to measure concentrations of nutrient of metabolites at two weeks pre-calving and at two weeks, two months and four months postcalving, respectively. The concentrations of nutrient metabolites [albumin, globulin, urea, beta-hydroxybutyrate (BHB) and inorganic phosphorus] suggested general underfeeding of energy and protein in the winter/late pregnancy period with some recovery in lactation. Energy constraints appeared again as the summer progressed. No dietary phosphate deficiency was found. BHB and albumin testing on serum yaks could be a useful tool to identify poor nutritional status during the winter and so illustrate the need for supplementation.