Application of growth models to South African Boer goat castrates and does under feedlot conditions.

Mathematical models may aid researchers in describing biological processes, like growth, in animals. This study aimed to collect the body weight data of 18 Boer goat castrates and 20 Boer goat does, from birth until maturity, to model growth and determine growth trends. This is a novel investigation as sufficient information on an age-weight database for these two Boer goat sexes from birth to maturity, is lacking. Using age-weight data, four nonlinear models, namely the Brody, Gompertz, Logistic and Von Bertalanffy growth models, were plotted and evaluated. The model parameters of each growth model were compared for differences between the two sexes. The statistical effectiveness of fit was determined for each model using AIC and RMSE, with R2 also being considered. All models except the Brody model, predicted significantly heavier mature weights for castrates. The Brody model was deemed unfit to describe Boer goat growth as the function severely over-predict weights from birth until maturity for both sexes. The Von Bertalanffy (R2 = 91.3) and Gompertz functions (R2 = 91.3) showed the best fit for Boer goat castrates, while the Gompertz model (R2 = 95.1) showed the best fit for Boer goat does. The Gompertz function is the preferred model to depict Boer goat growth overall, as it accurately characterized growth of both sexes. According to the Gompertz model the age at which the inflection point of the growth curve was reached, did not differ significantly between castrates and does (141.80 days versus 136.31 days). There was also no significant difference in maturation rate between the two sexes.

Wool production and quality traits of pure- and crossbred Merino-type sheep.

Very little information is available on the quality of wool produced by terminal crosses out of wool producing dam lines. This study was therefore undertaken to elucidate the wool quality traits of four crossbred lines relative to Merinos and Dohne Merinos, which served as dam lines. Each dam line was mated to rams of their own breed as well as to Dormer or Ile de France rams to create four crossbred lines, namely, Dohne x Dormer, Dohne x Ile de France, Merino x Dormer, and Merino x Ile de France, in addition to the purebred Dohne Merino and Merino lines. Four rams and four ewes from each of these lines were reared up to one year of age under optimal growth conditions and shorn at the end of that time. Fleeces were weighed and samples collected for analysis. Neither sex nor genotype influenced clean fleece weight or clean yield percentage, but fibre diameter differed between genotypes. Purebred Merino had the finest wool (18.26 µm) and the Merino x Dormer cross the coarsest (26.01 µm). However, all lines still produced wool that could be used in manufacturing clothing, while fleeces showed good uniformity. The two purebred lines had the highest comfort factor (> 98%). The crossbred lines produced a similar quantity of wool as the purebreds, although of poorer quality. All genotypes except Merino x Dormer appear to produce wool that could be processed into garments, although the crossbred wool would only be suitable for outerwear.

Determining and predicting feed intake in crossbred sheep from weaning until maturity.

Access to simple, accurate feed intake models would facilitate decision-making in feedlots as feed costs are a major part of operational expenditure. This study aimed to develop genotype-specific feed intake models for South African feedlot lambs. Four ram and four ewe lambs each of eight genotypes were raised under ideal growth conditions from weaning until 1 year of age. Feed intake and growth were monitored throughout this period. The intake data were then used to fit various models to predict daily feed intake, intake as percentage of body weight, cumulative intake and feed conversion ratio. No satisfactory univariate models could be found for the prediction of daily or percentage intake, but a good fit was found for cumulative intake data (R2 >0.80, P <0.01). The slope parameters of these linear models show a strong correlation (72%) with feed conversion and can therefore also serve as proxies for feed conversion. A model was also developed that can predict feed conversion ratio with a moderate accuracy (R2 =0.5, P <0.05) at a given body weight. The cumulative intake model was deemed accurate and simple enough for practical use.

Modelling and predicting fat deposition rates in various South African sheep crosses using ultrasound technology.

Producers require an accurate predictive tool that can determine the optimal point of slaughter based on fat depth. The modelling of fat deposition with a simple mathematical model could supply in this need. Dohne Merino and Merino ewes were crossed with Dorper, Dormer and Ile de France rams or rams of their own breeds to create two purebred (Dohne Merino and Merino) and six crossbred groups (Dohne x Dorper, Dohne x Dormer, Dohne x Ile de France, Merino x Dorper, Merino x Dormer and Merino x Ile de France) of offspring. Fat deposition of four lambs of each sex per genotypic group was monitored from 80 to 360 days using ultrasound, and the data subsequently fitted to various equations and evaluated for goodness of fit. A linear fitting of fat depth to age (R2 > 0.77) and live weight (R2 > 0.56) were deemed to provide the best fit. The slope parameters of the equations indicated that ewes deposited fat faster than rams and that Dorper crosses had the highest fat deposition rate. An attempt was also made to model loin muscle growth, but the model fit was judged to be unsatisfactory. The predictive models developed here are deemed suitable for inclusion in feedlot management systems to aid in the production of optimally classified lamb carcasses.

The effect of different dietary flavourants and salt levels on feed intake of juvenile ostriches.

Yearly the ostrich industry loses up to 40% of newly-hatched chicks, partly due to insufficient feed intake. This study was conducted to determine whether the inclusion of various feed flavourants would improve feed intake in ostrich chicks (Trial 1). Ninety-six dayold ostrich chicks were raised in groups of 12 at a Western Cape research farm until 28 days of age. These chicks were provided with free-choice access to a variety of flavoured diets, namely sweet, sour, bitter, salt or an unflavoured control diet. Chicks were found to prefer salty feed, as the salt-flavoured diet had the highest daily feed intake (34% of total) throughout the trial. Subsequently Trial 2 was conducted to determine the preferred level of dietary salt (Experiment 1) as well as the influence dietary salt had on various production parameters (Experiment 2). In Experiment 1, three groups of seven chicks each were offered ad libitum access to diets containing 4 g/kg, 14 g/kg, 24 g/kg, and 34 g/kg of salt respectively. Experiment 1 found that chicks preferred the diet containing 14 g salt/kg (36.4% of total daily feed consumed). For Experiment 2, 56 birds were divided into eight groups of seven. Conversely to the current conventional inclusion of 4 g salt/kg, Experiment 2 showed that chicks reared on a diet containing 14 g salt/kg had a 41.7% higher average daily gain than the group consuming 4 g salt/kg. It can therefore be concluded that ostriches prefer diets with a higher dietary salt level than current conventional diets provide (14 g/kg vs 4 g/kg).

Precision finishing of South African lambs in feedlots: a review.

In the intensification of sheep production systems, feedlot finishing plays a fundamental role in preparing lambs for slaughter, as well as relieving the grazing pressure on pasture. The profit margins in feedlot operations are often narrow and require the economics of scale to generate a sufficient income. In order to minimise expenses, intensive management and precision rearing of lambs to an ideal slaughter weight is needed to obtain premium carcass prices. The South African sheep industry is made up of wool, dual-purpose as well as meat type breeds, which also vary in terms of maturity. In order to implement precision finishing of South African lamb, a complete understanding of the growth, intake and fat deposition trends of growing lambs of different breed types is needed. This review outlines feedlot lamb production within the Southern African context for the major commercial breeds, while also providing insight in the considerations necessary to develop a decision support system for lamb rearing. Integrating such a decision support system into a lamb feedlot operation can then be used for precision finishing of lambs by predicting the optimal length of the feeding period and ideal slaughter weights of lambs.

Profile of cabanossi made with exotic meats and olive oil.

The effect of olive oil inclusion on the chemical and sensory characteristics in cabanossi made with ostrich and warthog meat was investigated. Ostrich meat from soybean oilcake (SBOC) and cottonseed oilcake dietary inclusion levels (CSOC), and olive oil were included at three levels (0%, 1% and 2%) resulting in six treatments. The fat content in the cabanossi increased with increasing levels of oil inclusion but were all <10%, which allows it to be classified as a low fat meat product. Total monounsaturated fatty acids in the cabanossi increased whilst total saturated fatty acids and total polyunsaturated fatty acids decreased as olive oil increased. The SBOC cabanossi had a lower fat and higher crude protein content. The inclusion of olive oil at 2% resulted in a cabanossi with increased tenderness, juiciness and cured red meat colour, all factors that appeal to the consumer, while the overall flavour descriptors were not adversely affected by the inclusion of olive oil.

Effect of cottonseed oilcake as a protein source on production of breeding ostriches.

1. South Africa currently produces 70% of the world's ostrich products. The profit margin of South African producers from the sale of ostrich meat, leather and feathers currently stands at 20%, 65% and 15%, respectively. 2. Local producers want to increase the production of ostrich products but keep production costs as low as possible. Maintaining optimal nutrition of breeding stock is necessary to increase the production of ostrich chicks, thereby decreasing the fixed costs per chick. 3. This research examined the impact on ostrich reproduction of replacing soya oilcake (SOC) as a protein supplement with cheaper cottonseed oilcake (CSOC). Although there are no data available on the impact of CSOC feed on ostrich reproduction, it is well known that gossypol, a naturally occurring toxin in cotton plants, negatively affects male reproduction in other monogastric species and that it may also reduce appetite. 4. Ninety-six breeding ostrich pairs were divided into two groups to compare the effects of diet (CSOC and SOC) during the breeding season on ostrich-breeding parameters. The replacement of SOC with CSOC had no significant effect on the number of total eggs produced (47.8 ± 5.3 versus 48.3 ± 5.1 per breeding pair, respectively) or infertile eggs (31.5 ± 3.9 versus 38.0 ± 5.2, respectively). Also, the number of dead-in-shell chicks did not differ significantly between groups (20.2 ± 3.3 versus 26.8 ± 3.8, respectively). 5. Even though none of these breeding parameters differed, the replacement of SOC with CSOC in the diets of breeding birds led to significantly more chicks hatching per hen from breeding birds fed on the SOC (36.1 ± 4.8) than the CSOC diet (17.2 ± 3.8). 6. Although it would thus seem that feeding breeding ostriches CSOC instead of SOC as a protein supplement will have a detrimental effect on chick production, more data are required to deliver a definitive answer.

The reproductive response of female ostriches to dietary protein.

A study was conducted with breeding ostriches over two consecutive breeding seasons to determine their response to different concentrations of a well-balanced dietary protein. Five concentrations of protein were fed to both females and males at an intake of 2.5 kg/bird d. The respective diets contained 75, 91, 108, 123 and 140 g protein/kg feed with energy held constant at 9.2 MJ metabolisable energy/kg feed. Egg production (mean ± SE, 39.1 ± 3.6 eggs/female/season) was unaffected by dietary protein concentration. Similarly, no significant trends were found for the number of unfertilised eggs (9.1 ± 1.8), dead-in-shell chicks (8.2 ± 1.3), the number of chicks hatched (19.5 ± 2.5) and change in the mass of females (-16.3 ± 10.2 kg). Egg weight decreased linearly as dietary protein content increased. Age of the ostrich female had a highly significant effect on the number of eggs laid, the number of chicks hatched, the number of dead-in-shell and infertile eggs produced per hen, as well as the mass change of female breeding birds, but did not affect the response of any of these variables to dietary protein content. It was concluded that ostriches do not benefit from dietary protein contents greater than about 75 g/kg when this is fed at a daily total feed intake rate of 2.5 kg/bird during the breeding season.

The effect of dietary energy concentrations on production variables of ostrich chicks (Struthio camelus var. domesticus).

The effects of different dietary energy concentrations on ostrich production variables were examined in two separate trials. The first trial tracked changes in production variables from the pre-starter phase through the starter phase and grower phase. The second trial was based on the finisher phase per se. In both trials, the influence of dietary energy on feed intake, feed conversion ratio (FCR) and growth variables was investigated. Additionally, basic abattoir weights were recorded, and measurements of the feathers and skin were performed. In both trials, three diets with different concentrations of dietary energy were given during each phase where the low-, medium- and high-energy concentrations for each phase were as follows: 13.5, 14.5 and 15.5 MJ ME/kg feed pre-starter; 12.5, 13.5 and 14.5 MJ ME/kg feed starter; 10.5, 11.5 and 12.5 MJ ME/kg feed grower and 9.5, 10.5 and 11.5 MJ ME/kg feed finisher. Feed and water were available ad libitum in both trials. Overall, it was found that the best performance for growth, FCR, skin size and grade, live weight, carcass weight and thigh weight were obtained on the medium-energy diet during the pre-starter, starter and grower phases. During the finisher phase, improved growth rate and tanned skin size was found in birds given the diet with the highest energy concentration (11.5 MJ ME/kg feed). Carcass weight, growth rate and certain feather variables were also significantly influenced by gender.

The growth response of ostrich (Struthio camelus var. domesticus) chicks fed on diets with three different dietary protein and amino acid concentrations.

1. Feeding costs are the largest expense in an ostrich production system, and protein is one of the more expensive components of the diet. This study evaluated the growth response of ostrich chicks on diets containing different concentrations of protein (amino acids). The diets were formulated to contain three concentrations of protein (one diet with 20% less protein than the conventional concentration, L; one diet with the conventional concentration of protein, M and one diet with 20% more protein than the conventional concentration, H) for each of the phase diets. The phase diets were pre-starter, starter, grower and finisher. 2. This study includes the analysis of ostrich body weight (BW) by modelling growth with linear polynomial and non-linear functions for all the data not separated for treatments. In total, 3378 BW recordings of 90 animals were collected weekly from hatch (d 0) to 287 d (41 weeks) of age. 3. Seven non-linear growth models and three linear polynomial models were fitted to the data. The growth functions were compared by using Akaike's information criterion (AIC). For the non-linear models, the Bridges and Janoschek models had the lowest AIC values for the H treatment, while the Richards curve had the lowest value for M and the von Bertalanffy for the L treatment. 4. For the linear polynomial models, the linear polynomial of the third degree had the lowest AIC values for all three treatments, thus making it the most suitable model for the data; therefore, the predictions of this model were used to interpret the growth data. Significant differences were found between treatments for growth data. 5. The results from this study can aid in describing the growth of ostriches subjected to optimum feeding conditions. This information can also be used in research when modelling the nutrient requirements of growing birds.

Effect of cottonseed oilcake inclusion on ostrich growth performance and meat chemical composition.

This study investigated the effect of replacing dietary soybean oilcake meal with increasing levels of cottonseed oilcake meal (CSOCM) on the growth performance and meat (Iliofibularis muscle) chemical composition of ostriches in order to decrease total feed costs. A total of 105 ostriches were divided into five feeding groups according to the CSOCM inclusion level in the whole diet: Control (0% CSOCM), 3%, 6%, 9% and 12% CSOCM (of the whole diet), and fed with experimental diets from 6 to 13 months of age. As a result of feeding CSOCM, the final live weight and the average daily gain significantly increased in the 12% CSOCM group. The proximate composition, cholesterol content, mineral and fatty acid profile of the meat remained unaffected. Thus CSOCM may be used as an alternative protein source to the more expensive soybean oilcake meal in ostrich nutrition.

The composition of egg yolk absorbed by fasted ostrich (Struthio camelus L.) chicks from 1 to 7 days posthatching and for ostrich (Struthio camelus L.) chicks from 1 to 16 days posthatching on a prestarter broiler diet.

This study was performed to obtain information on yolk utilization in fasted and fed ostrich chicks posthatching. The fasted trial lasted for 7 d, whereas the fed trial continued for 16 d. Fasted ostrich chicks showed a decrease of 31.3 g of BW, with yolk weight decreasing by 28.9 g daily after hatching. Yolk weight comprised 28% of 1-d-old ostrich chick BW and decreased to 12% at 7 d of age. Only 44.4% of the fasted ostrich chick yolk was assimilated over the trial period. Crude protein content of the yolk decreased by 13.2 g daily. Fat content increased by 1.77% daily, whereas total yolk fat weight decreased with 8.91 g daily. Slaughter weight of fed ostrich chicks increased, with yolk weight decreasing by 16.3 g daily. Yolk content for fed ostrich chicks was 26% of BW at 2 d of age. Ostrich chicks absorb 30% of yolk over the first 4 d, 67% after 8 d, and only deplete the yolk after 14 d posthatch. Fasted ostrich chicks absorbed the yolk content at a rate of 28.9 g/d, compared with 22.3 g/d over the first 8 d and 16.3 g/d over the 16 d for fed ostrich chicks. The CP content of the yolk decreased by 6.84 g daily in fed ostrich chicks, whereas fat content of the yolk increased by 1.39% daily, although total yolk fat weight decreased by 6.61 g daily. Yolk weight and total CP decreased faster over the first 7 d in the fasted ostrich chicks compared with the fed ostrich chicks, which indicated that the decrease in yolk weight could be attributed to absorption of protein from the yolk. Fat content decreased faster over the first 8 d from the yolk of the fed ostrich chicks compared with that from the yolk of the fasted ostrich chicks, which could indicate that external feed has a positive influence on the absorption of fat from the yolk content.

Effect of slaughter age and sex on the production output of South African Black ostriches.

1. The effects of different slaughter ages and sex on the yield and quality of economically important end-products of slaughtered ostriches was examined to determine the most economic slaughter age for growing/finishing ostriches. Two batches of 4- and 6-month-old ostriches were assigned to 10 treatment groups and fed ad libitum up to slaughter ages of 8·5, 10·5, 12·5, 14·5 and 16·5 months. Slaughter weight, cold carcase yield, skin surface area, dry skin grade, feather yield and feed intake of ostriches were measured for each age. 2. Cold carcase yields and total feather yields of males were higher than females but yields of other products were similar. 3. Slaughter weight, cold carcase yield, skin surface area, dry skin grade, feather yield and feed intake increased with age with significant differences between most age groups. Cold carcase weight increased by approximately 2·2 kg and skin surface area increased by 3·1 dm³ with each additional month of growth but the quality (grade) of skins and the proportion of first grade skins decreased with increasing age. This, together with an increase in feed intake associated with age to slaughtering should be taken into account when determining the optimal slaughter age. 4. The set of biological variables established in this study can be used to determine the most economical slaughter age under varying market conditions.

Prediction of the chemical composition of freeze dried ostrich meat with near infrared reflectance spectroscopy.

Near infrared reflectance spectroscopy (NIRS) was used to predict the chemical composition of freeze-dried ostrich meat samples. Tenderloin (M. ambiens), big drum (M. iliofibularis) and fan fillet (M. gastrocnemius) samples (n=160) were included in the study. Samples were minced, freeze-dried and analysed according to standard laboratory procedures for ash, dry matter (DM), crude protein (CP) and fat content. Samples were scanned (1100-2500 nm) and partial least-square regression (PLSR) was used to predict the chemical composition. Multiple correlation coefficients (r) and standard errors of calibration (SEC) for the chemical analysis of freeze-dried ostrich meat were: ash (0.72; 0.29%); DM (0.72; 1.01%); CP (0.98; 0.55%); and fat (0.99; 0.29%). The r values for the validation set and the standard error of performance (SEP) for the different constituents were: ash (0.71; 0.23%); DM (0.84; 0.72%); CP (0.97; 0.64%); and fat (0.99; 0.18%). Calibrations were accurate for CP and fat.

The effect of dietary fish oil rich in n-3 fatty acids on the organoleptic, fatty acid and physicochemical characteristics of ostrich meat.

The effect of different levels of unrefined fish oil in the diet on ostrich Musculus iliofibularis was evaluated in a completely randomised experimental design, where a supplementary energy rich feed, containing 6.7% fish oil, was fed at four different levels over a 7-month period. An increase in the amount of fish oil consumed was found to have had no significant effect on the sensory characteristics of ostrich meat, although there was a tendency towards an increase in fishiness, for both aroma and flavour. Increased concentrations of fish oil, however, did have a significant effect on the aroma and flavour of the abdominal fat pads. The muscle pH(f) and muscle lightness (L*) revealed a significant reduction, with increased energy intake. However, the increased energy intake had no effect on the chemical composition (moisture, protein, fat, and ash content) of the meat. The fatty acid profile of both adipose tissue and muscle was altered as a result of the consumption of fish oil. The SFA concentration increased, while the PUFA concentration decreased with increasing dietary levels. The MUFA concentration remained constant for all four groups.

The effect of dietary energy and protein levels on production in breeding female ostriches.

1. In a study spanning two breeding seasons, we assessed the effect of different dietary energy and protein levels on body mass, body condition, and egg production of female ostriches. 2. During the first breeding season, groups were given diets with energy concentrations of 8.5, 9.5 and 10.5 MJ/kg dry mass (DM) metabolisable energy (ME) and protein concentrations of 135, 150 and 165 g/kg. In the second breeding season, groups were given diets with ME of 7.5, 8.5 and 9.5 MJ/kg and protein contents of 105, 120 and 135 g/kg. 3. Body mass of birds on diets of 7.5 and 8.5 MJ/kg ME decreased significantly in the course of the breeding season compared with birds fed on diets with higher energy contents and body measurements decreased, suggesting a loss of body condition. 4. Females fed on diets containing only 7.5 MJ/kg ME produced significantly fewer eggs at significantly longer intervals, resulting in fewer chicks hatched. 5. There was no significant difference in egg mass, initial chick mass, chick survival to one month of age and body mass of chicks at one month. 6. Dietary protein concentrations had no effect on egg production, egg mass, hatchability, initial chick mass, chick survival or chick mass at one month old. 7. The female ostriches regained their original body mass during the 4-month rest period between breeding seasons, but significant differences in some parameters during the second breeding season suggest that they may not have fully recovered their body condition. 8. A dietary energy content of 7.5 MJ/kg proved to have an adverse effect on egg production by breeding female ostriches, and it may be concluded from this study that a diet containing 8.5 MJ ME/kg DM and 105 g/kg protein should be regarded as the minimum that can be used for breeding female ostriches without compromising egg production.

Development of the digestive tract in the ostrich (Struthio camelus).

A study was conducted to investigate changes in the development of the gastrointestinal tract (GIT) in relation to body growth of growing ostriches. There was an 11-fold increase (P < 0.001) in body weight between 3 and 72 days of age. The relative (to body weight) weight of the proventriculus/gizzard, caeca and colon also increased (P < 0.001) with age. The relative weight of the small intestine peaked at 41 days of age and then tended to decline (P < 0.05) subsequently. The relative weight of the pancreas peaked at 27 days of age and remained fairly stable thereafter. The activities of chymotrypsin and lipase declined (P < 0.001) with age between 3 and 72 days. At 3 days of age, the protein content of the duodenal mucosal homogenate was higher (P < 0.001) than that of the jejunum or ileum, but at all subsequent periods the jejunal protein content was the highest. The protein content of the intestinal brush-border membrane was higher (P < 0.001) at the jejunum than at the duodenum or ileum. The specific activity of maltase declined (P < 0.001) with age in all three regions, most especially between 3 and 27 days of age. The activity of alkaline phosphatase (AP) at 41 and 55 days of age was higher (P < 0.001) in the duodenum than in the jejunum or ileum. The activity of AP fluctuated with age in the duodenum but there was a more defined decline (P < 0.001) with age in the jejunum and ileum. The relative protein content of the liver increased (P < 0.001) with age, with two peaks at 27 and 55 days of age. Arginase activity was not detected in the liver of 3-day old chicks and was not significantly affected by age between 27 and 72 days of age. The pattern of development observed is similar to that in growing poultry. There is, however, a need for evaluation at closer intervals in early life as well as an in-depth assessment of the morphometry of the intestinal mucosa.

The true metabolisable energy content of canola oilcake meal and full-fat canola seed for ostriches (Struthio camelus).

1. The true metabolisable energy (TME) of canola oilcake and full-fat canola seed was determined for ostriches to broaden our knowledge of canola as a potential protein and energy source for ostriches. 2. Both test materials were diluted with a basal diet, fed to ostriches and TME-values estimated by multiple regression analysis. 3. The TME values for canola oilcake meal and full-fat canola seed for ostriches were respectively 13.76 MJ kg(-1) and 22.5 MJ kg(-1). 4. The TME values obtained for these 2 important protein sources will assist in the more accurate formulation of diets for ostriches.

The influence of dietary crude protein intake on bone and mineral metabolism in sheep.

Increased dietary protein consumption is thought to cause calciuresis, a negative calcium balance and increased bone loss that may result in skeletal deformities and fracture. To explore this hypothesis, 40 approximately 100-day-old meat-type Merino ram lambs were fed, for 6 months, diets with an increasing crude protein (CP) content (114, 142, 171 and 190 g/kg DM) but approximately on an iso-nutrient basis with regard to metabolisable energy, calcium and phosphorus. Increased protein consumption modestly (NS) enhanced calciuresis and resulted in significant (P < or = 0.01) limb skewness. This could not, however, be ascribed to osteopaenic bones, and compared with animals consuming lower protein rations, the bone mineral density (BMD) and vertebral trabecular bone volume of animals fed high protein diets were significantly increased: the BMD of thoracic vertebrae was positively related to the CP intake (r = 0.62; P < or = 0.001). In animals consuming higher protein diets, skeletal radiology and quantitative bone histology revealed no evidence of increased bone turnover as would be expected in animals that are in negative calcium balance. No relationship existed between limb skewness and the growth rate of lambs. However, the ratio of Ca:P in the forelimb (r = -0.98), vertebrae (r = -0.72) and rib (r = -0.42) was found to be inversely correlated with increased protein intake and resulted from an increase in the phosphorus content of bone, while the amount of bone calcium was unaffected. We conclude that qualitative micro-architectural abnormalities, and not mere bone loss, may underlie the skeletal deformities induced by increased protein consumption in sheep.