The present overview is intended to point the readers’ attention to the important subject of calcium orthophosphates. These materials are of the special significance because they represent the inorganic part of major normal (bones, teeth and dear antlers) and pathological ( i.e. those appearing due to various diseases) calcified tissues of mammals. Due to a great chemical similarity with the biological calcified tissues, many calcium orthophosphates possess remarkable biocompatibility and bioactivity. Materials scientists use this property extensively to construct artificial bone grafts that are either entirely made of or only surface-coated with the biologically relevant calcium ortho-phosphates. For example, self-setting hydraulic cements made of calcium orthophosphates are helpful in bone repair, while titanium substitutes covered by a surface layer of calcium orthophosphates are used for hip joint endoprostheses and as tooth substitutes. Porous scaffolds made of calcium orthophosphates are very promising tools for tissue engineering applications. In addition, technical grade calcium orthophosphates are very popular mineral fertilizers. Thus ere calcium orthophosphates are of great significance for humankind and, in this paper, an overview on the current knowledge on this subject is provided.

https://www.mdpi.com/1996-1944/2/2/399/pdf

Calcium Orthophosphates in Nature, Biology and Medicine

Nutrition-parasite interaction

Nutrition and parasite interaction

Mineralized biological tissues offer insight into how nature has evolved these components to optimize multifunctional purposes. These mineral constituents are weak by themselves, but interact with the organic matrix to produce materials with unexpected mechanical properties. The hierarchical structure of these materials is at the crux of this enhancement. Microstructural features such as organized, layered organic/inorganic structures and the presence of porous and fibrous elements are common in many biological components. The organic and inorganic portions interact at the molecular and micro-levels synergistically to enhance the mechanical function. In this paper, we report on recent progress on studies of the abalone and Araguaia river clam shells, arthropod exoskeletons, antlers, tusks, teeth and bird beaks.

Structure and Mechanical Properties of Selected Biological Materials

In early 1989, two-thirds of the Soay sheep population on St Kilda died over 12 weeks. Post-mortem examinations revealed emaciated carcasses and considerable nematode burdens, with protein-energy malnutrition as the probable cause of death. Haematological and blood biochemical changes in the sheep, as well as fecundity of gastrointestinal nematodes, suggested the hosts were immunosuppressed. In parallel, laboratory experiments in which Soay sheep on a high plane of nutrition were artificially infected with Ostertagia circumcincta, showed no clinical signs or mortality when supporting worm burdens similar to those recorded in dead sheep on St Kilda. Anthelmintic treatment of a group of animals increased daily survival rates in ewes and male lambs, although treated animals became re-infected as the 'crash' progressed. It is suggested that parasites contribute to mortality in malnourished hosts, exacerbating the effects of food shortage.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0031182000074679

The role of nematode parasites in Soay sheep (Ovis aries L.) mortality during a population crash.

Forty pregnant sheep were allocated to four groups and maintained indoors in individual pens on a pelleted diet. During the last 6 weeks of pregnancy and the first 6 weeks of lactation groups were infected daily with 4000 larvae of Ostertagia circumcincta or remained as controls in a cross-over design. Thus groups were either not infected (CC), infected only during pregnancy (IC), during lactation (CI) or during both pregnancy and lactation (II). Food was offered on the basis of body weight at the beginning of pregnancy and lactation. Food intake, body-weight change, faecal egg counts, plasma pepsinogen and milk production were measured weekly, wool growth and fibre diameter during 21-day periods and tensile strength of wool over the whole experimental period.Eggs were seen in faeces of only three sheep infected during pregnancy, but in all sheep infected during lactation; maximum mean values were 467 ± 144 and 222 ± 58 eggs/g fresh faeces in CI and II sheep, respectively. Pepsinogen concentrations rose after 1 week of infection during pregnancy and lactation; peak values were 868 + 57 and 1104 ± 146 m-u/l, respectively.Infection reduced food intake by 16% during lactation but had no effect during pregnancy. There were significant interactions between pregnancy and lactational treatments on intake during lactation. Infection during lactation increased bodyweight loss; mean values were 57, 40, 114 and 78 g/day for groups CC, IC, CI and II respectively. Milk production was decreased during weeks 4–6 of lactation, mean values being 1·59 and 1·32 kg/day in control and infected groups, respectively.Infection reduced wool growth and wool fibre diameter by 20 and 7%, respectively, during the final 3 weeks of infection during lactation. The staple strength of wool grown during the experiment was reduced by 14, 45 and 23% in IC, CI and II groups, respectively. Infection moved the point of greatest wool tenderness from parturition in control sheep to a time during the period of infection, particularly when infection occurred during lactation.

Effect of daily infection with Ostertagia circumcincta larvae on food intake, milk production and wool growth in sheep

Kinetic studies of Ca metabolism, using 45CaCl32, were carried out on two mature red deer stags during the period of maximum rate of Ca deposition in the antlers. They were offered green-feed oats to provide energy for maintenance; the diet provided approximately 42mg Ca/kg W per day.Ca appeared to be irreversibly lost from the circulation into the antlers and could be treated for kinetic purposes in the same way as loss of Ca from the body in milk. The size of the rapidly exchangeable Ca pool in the body, excluding the antlers, was 0·21 g/kg W, similar to estimates for lactating cattle. Rates of Ca deposition in the antlers of the two stags, calculated from the model of Ca metabolism, were 58·4 and 38·6 mg Ca/kg W per day. Net endogenous loss was 6–7 mg Ca/kg W per day, much lower than estimates available for other ruminant species. Only 25–40% of Ca requirement or 11–24 mg Ca/kg W per day was derived from the diet, suggesting that the availability of Ca in greenfeed oats is much lower than current estimates for forages. Bones removed on completion of the experiment showed evidence of considerable skeletal demineralization.In other stags subjected to stable Ca balances at the same stage of antler growth, while consuming ryegrass-white clover forage, 60–80% of Ca requirement was derived from the diet, with calculated rates of true absorption of 32–46 mg Ca/kg W per day. These rates of Ca absorption are low compared with values observed in other ruminants at times of high Ca demand such as during lactation.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0021859600080783

Calcium metabolism in red deer (Cervus elaphus) offered herbages during antlerogenesis: kinetic and stable balance studies

Ninety 4-month-old wether lambs were allocated to an initial slaughter group (n =10) or to one cell (n= 5) of a 4 × 4 factorial treatment design involving four levels of infection with Ostertagia circumcincta (0, 1000, 2000 and 4000 larvae/day) and Trichostrongyluscolubriformis (0, 1000, 2000 and 3000 larvae/day) They were maintained indoors in individual pens and offered freshly cut ryegrass-white clover herbage during an 84-day period of infection after which they were slaughtered Body protein, fat, water, Ca and P contents were determined Feed digestibility was determined in all sheep during 5-day periods during weeks 2, 5, 8 and 11 Faecal egg counts were determined and blood samples obtained at intervals and total worm counts done at slaughterThe effects of mixed infection on feed intake and body-weight gain were multiplicative Mean DM intake of sheep infected simply with 3000 larvae of T colubriformis or with 4000 larvae of O circtimcincta was reduced by 10 and 8% respectively, but in those infected simultaneously intake was reduced by 30% Energy retention was depressed mainly by reduction in gross efficiency of use of metabolizable energy in infections with T colubriformisand by reduction in feed intake in infections with O circumcincta The additional effect of mixed infection occurred mainly through further depression in feed intakeThere was no interaction between infections in effect on deposition of Ca or P in the body, both species having significant effect Infection with T colubriformis caused hypophosphataemia and hypocalcaemia, but infection with O circumcincta had no effectThe number of worms established by the infections was generally low compared with previous studies with conserved and concentrate feeds This was associated with relatively low pathogenicity in infection with O circumcincta and normal pathogenicity with T colubriformisInfection with T colubriformis reduced the number of adult worms of O circumcincta present at slaughter

Effect of concurrent infection with Ostertagia circumcincta and Trichostrongylus colubriformis on the performance of growing lambs consuming fresh herbage

In two experiments Dorset ewes were offered low (LP) or high (HP) herbage allowances during pregnancy to induce light (45–50 kg) or heavy (60–65 kg) post-partum body weights, respectively. During the first 6 weeks of lactation three herbage allowances were offered in a 2 x 3 factorial design: 2 (LL), 5 (ML) and 8 (HL) kg D.M./ewe per day. In the first experiment (Expt 1) lambs were removed and ewes machine-milked twice daily. In the second (Expt 2) they were suckled by two lambs; a further group on the ML allowance (MML) was machine-milked. Ewes were slaughtered during early pregnancy, post-partum and after 6 weeks of lactation for determination of body composition. Diet selection and faecal output were measured during lactation.Absolute level of milk production was not affected by pregnancy nutrition when rearing two lambs and producing 2·0–2–7 kg milk/day or at 30–50% lower milk production when machine-milked. When expressed as g/kg W0·75 per day milk production was 14% greater in LP than in HP ewes. Milk fat content was higher at low allowances and was positively related to rate of body fat mobilization. Milk protein concentration was lower in suckled than in machine-milked ewes (40 ν. 47 g/kg) though total milk protein secreted (g/day) was similar. Milk production was 11–13% greater in ewes bearing twin lambs compared with those bearing singles whether machine-milked or suckling two lambs.Mean intakes during the 6 weeks of lactation were 58, 69 and 73 g DOM/kg W0·75 per day, respectively, for LL, ML and HL groups when machine-milked and 51, 75 and 83 g DOM/kg W0·75/day, respectively, for ewes rearing two lambs. LP ewes consumed 13% (Expt 1) and 17% (Expt 2) more feed (g DOM/kg W0·75/day) during lactation than HP ewes, though in absolute terms (kg D.M./day) there was no difference. The difference in OMD between herbage offered (OMD = 0·77) and consumed ranged from 0 when sheep grazed to a residual herbage mass of 910 kg D.M./ha to + 0·04 when residual herbage was < 1600 kg D.M./ha.All sheep, irrespective of pregnancy nutrition, milk production or herbage allowance, were in negative body energy balance during lactation. Mobilization of body fat during lactation averaged 40 g/day for machine-milked and 150 g/day for suckled ewes and was greatest in HPLL groups (92 and 219 g/day in Expts 1 and 2, respectively). In LP groups body protein loss during pregnancy was 10 and 16 g/day in Expts 1 and 2, respectively, and little further net protein loss occurred during lactation. The maximum rate of body protein loss in HP groups was 30 g/day in ewes rearing two lambs on the low herbage allowance.Maintenance energy requirement during lactation averaged 0·238 MJ ME/kg W per day for ewes in both experiments; efficiency of use (Kl, (t)) of total energy available above maintenance for milk synthesis (namely, milk energy/ME intake - estimated energy requirement for maintenance (MEm + mobilized tissue energy) decreased from 0·84 to 0·51 with increasing rate of tissue energy mobilization. There was a positive relationship between Kl(t) and the proportion of mobilized energy derived from body protein.The overall energy requirement of lactating ewes well-fed during pregnancy was similar to previous estimates (Agricultural Research Council, 1980) but that of sheep undernourished during pregnancy was 10–20% greater.

Effect of herbage allowance during pregnancy and lactation on feed intake, milk production, body composition and energy utilization of ewes at pasture

In a study of antler growth and mineralisation, 18 red deer stags aged 4 years and older were individually penned immediately before and during antler growth and offered one of three pelleted rations which varied in protein and calcium (Ca) content. One antler was removed from a stag in each treatment group at 28, 42, 56, 70, 91, and 112 days of growth. The contralateral antler was removed when epidermal tissue began to be shed (velvet shedding). No effect of nutritional treatment on antler growth was detected. Mean time of velvet shedding was 164 days after the start of antler growth. Date of antler casting (range = 56 days) was more variable than date of velvet shedding (range = 24 days). Increase in length and weight followed a typical growth curve with the most rapid phases, 0.67 cm/day and 13.7 g/day respectively, occurring between 28 and 112 days after casting. By 112 days, antlers had achieved about 95 and 127% of final length and weight. Three phases of mineralisation were demonstrated. T...

https://www.tandfonline.com/doi/pdf/10.1080/00288233.1987.10421889

A. R. Sykes

Papers

Effect of daily infection with Ostertagia circumcincta larvae on food intake, milk production and wool growth in sheep

Calcium metabolism in red deer (Cervus elaphus) offered herbages during antlerogenesis: kinetic and stable balance studies

Effect of concurrent infection with Ostertagia circumcincta and Trichostrongylus colubriformis on the performance of growing lambs consuming fresh herbage

Effect of herbage allowance during pregnancy and lactation on feed intake, milk production, body composition and energy utilization of ewes at pasture

Growth and mineralisation of antlers in red deer (Cervus elaphus)