The Cornell Net Carbohydrate and Protein System (CNCPS), a mechanistic model that predicts nutrient requirements and biological values of feeds for cattle, was modified for use with sheep. Published equations were added for predicting the energy and protein requirements of sheep, with a special emphasis on dairy sheep, whose specific needs are not considered by most sheep-feeding systems. The CNCPS for cattle equations that are used to predict the supply of nutrients from each feed were modified to include new solid and liquid ruminal passage rates for sheep, and revised equations were inserted to predict metabolic fecal N. Equations were added to predict fluxes in body energy and protein reserves from BW and condition score. When evaluated with data from seven published studies (19 treatments), for which the CNCPS for sheep predicted positive ruminal N balance, the CNCPS for sheep predicted OM digestibility, which is used to predict feed ME values, with no mean bias (1.1 g/100 g of OM; P > 0.10) and a low root mean squared prediction error (RMSPE; 3.6 g/100 g of OM). Crude protein digestibility, which is used to predict N excretion, was evaluated with eight published studies (23 treatments). The model predicted CP digestibility with no mean bias (-1.9 g/100 g of CP; P > 0.10) but with a large RMSPE (7.2 g/100 g of CP). Evaluation with a data set of published studies in which the CNCPS for sheep predicted negative ruminal N balance indicated that the model tended to underpredict OM digestibility (mean bias of -3.3 g/100 g of OM, P > 0.10; RMSPE = 6.5 g/100 g of OM; n = 12) and to overpredict CP digestibility (mean bias of 2.7 g/100 g of CP, P > 0.10; RMSPE = 12.8 g/100 g of CP; n = 7). The ability of the CNCPS for sheep to predict gains and losses in shrunk BW was evaluated using data from six studies with adult sheep (13 treatments with lactating ewes and 16 with dry ewes). It accurately predicted variations in shrunk BW when diets had positive N balance (mean bias of 5.8 g/d; P > 0.10; RMSPE of 30.0 g/d; n = 15), whereas it markedly overpredicted the variations in shrunk BW when ruminal balance was negative (mean bias of 53.4 g/d, P < 0.05; RMSPE = 84.1 g/d; n = 14). These evaluations indicated that the Cornell Net Carbohydrate and Protein System for Sheep can be used to predict energy and protein requirements, feed biological values, and BW gains and losses in adult sheep.

A mechanistic model for predicting the nutrient requirements and feed biological values for sheep

https://pubag.nal.usda.gov/pubag/downloadPDF.xhtml?id=8183&content=PDF

Mechanisms Regulating Feed Intake, Energy Expenditure, and Body Weight in Poultry

Perspectives on the endocrinology of poultry growth and metabolism.

All organisms face tradeoffs with regards to how limited energy resources should be invested. When is it most favorable to grow, to reproduce, how much lipid should be allocated to storage in preparation for a period of limited resources (e.g. winter), instead of being used for growth or maturation? These are a few of the high consequence fitness ‘decisions’ that represent the balance between energy acquisition and allocation. Indeed, for animals to make favorable decisions about when to grow, eat, or reproduce, they must integrate signals among the systems responsible for energy acquisition, storage, and demand. We make the argument that leptin signaling is a likely candidate for an integrating system. Great progress has been made understanding the leptin system in mammals, however our understanding in fishes has been hampered by difficulty in cloning fish orthologues of mammalian proteins and (we assert), underutilization of the comparative approach.

/pdf/leptin-in-teleost-fishes-an-argument-for-comparative-study-2xyri68trv.pdf

Leptin in Teleost Fishes: An Argument for Comparative Study

Accounting for multi-functionality of sheep farming in the carbon footprint of lamb: A comparison of three contrasting Mediterranean systems.

https://citarea.cita-aragon.es/citarea/bitstream/10532/1788/1/2011_447.pdf

An integrated sustainability assessment of mediterranean sheep farms with different degrees of intensification

Identification of three single nucleotide polymorphisms in the chicken insulin-like growth factor 1 and 2 genes and their associations with growth and feeding traits

The effect of caponisation on carcass composition by parts and tissues was examined. Twenty-eight castrated and twenty male Penedesenca Negra chicks reared under free-range condi- tions were slaughtered at 28 weeks of age. The birds were castrated at 4 or 8 weeks. The left sides of the carcasses were quartered (wing, breast, thigh and drumstick), and the parts dissected into the tis- sue components (skin, subcutaneous fat, intermuscular fat, muscle, bone and tendons). Capons showed more abdominal, intermuscular and subcutaneous fat than the cocks, both at the same slaugh- ter age and at the same weight. The breast and thigh were heavier in the capons than in the cocks. However, the whole muscle mass in the breast was increased by caponisation. This favourable effect was achieved at the expense of decreasing the carcass yield. The age of castration up to 8 weeks did not affect the carcass composition of the parts and tissues. chicken / capon / carcass / tissue composition

/pdf/comparison-of-carcass-composition-by-parts-and-tissues-43q0s2i3xe.pdf

Comparison of carcass composition by parts and tissues between cocks and capons

Analysis by near-infrared spectroscopy (NIRS) was investigated as a means of predicting quality parameters of ovine milk Calibration equations were developed with samples of ovine milk obtained from a flock of Manchega and Lacaune dairy ewes at different stages of lactation for a wide variation in milk composition Prediction equations for milk protein, fat, and total solids content were developed by use of reflection or transflection methods to measure absorbance values Accuracies of measurements were compared R2 (squared multiple correlation coefficient) values were satisfactory in most cases The highest R2 value for milk protein content (092) was obtained in transflectance mode with unhomogenized milk The highest R2 values for fat (099) and total solids (098-096) content were obtained in both a transflectance mode without sample conditioning and in a transflectance mode with milk homogenized at 40 degrees C To validate the calibration, an independent set of 40 milk samples was used The best r2 (simple correlation coefficient) values for protein, fat, and total solids were 092, 097, and 092, respectively The study showed that NIRS is a potentially useful technique for evaluating the composition of unhomogenized ovine milk

/pdf/determination-of-fat-protein-and-total-solids-in-ovine-milk-zdmasnhizz.pdf

Determination of fat, protein, and total solids in ovine milk by near-infrared spectroscopy.

Two experiments were carried out with pregnant (experiment 1) and lactating ewes (experiment 2), to compare dry-matter (DM) intake, and total tract apparent digestibility, digesta kinetics and weight of digestive tract contents of Lacaune and Manchega sheep, with the aim of explaining possible differences between the breeds in voluntary food intake. In experiment 1, 20 3-year-old single-bearing pregnant ewes, 10 Manchega and 10 Lacaune, were permanently housed for the last 10 weeks of pregnancy. The diet used consisted of lucerne hay, offered ad libitum, supplemented with 0·3 kg/day of concentrate. DM and digestible DM intake per kg M0·75 were higher (P < 0·01) in Lacaune than in Manchega sheep. Breed did not affect total tract apparent digestibility, fractional rates of passage, transit time, total mean retention time, or weight of digestive tract contents. Changes in body weight and body condition score were similar between breeds. In contrast, Lacaune lambs tended (P = 0·09) to weigh less than Manchega lambs, suggesting genetic differences in the energy utilization between breeds in late pregnancy. Higher DM intake observed in Lacaune sheep may have been related to a higher energy demand for mammary development. In experiment 2, 32 3-year-old lactating multiparous ewes, 16 Manchega and 16 Lacaune, were permanently housed during the first 12 weeks of lactation. The experimental diet used was based on a mixture of maize silage and dehydrated lucerne (10: 1, fresh weight basis), offered ad libitum, and supplemented with 0·8 kg/day of concentrate. Milk, fat and protein yield as well as DM and digestible DM intake in Lacaune ewes was higher (P < 0·01) than in Manchega ewes. DM intake was constant in Lacaune sheep with advancing lactation, while in Manchega sheep DM intake decreased. Throughout this period Lacaune ewes lost 0·5 kg of body weight while Manchega gained 4·4 kg. Breed did not affect either apparent digestibility of DM, organic matter and neutral-detergent fibre, or fractional rates of passage, transit time and total mean retention time. The weight of total tract digestive contents was greater (P < 0·05) in Lacaune than in Manchega sheep, particularly in the reticulo-rumen. Results suggest that the scheme of selection in Lacaune dairy sheep has increased milk yield together with voluntary food intake, the latter being associated with an increase in the rumen fill capacity. The higher milk yield of Lacaune ewes cannot be attributed to the higher DM intake only; other factors, i.e. mobilization of fat reserves, are required to support this higher milk output.

Comparison of voluntary food intake, apparent digestibility, digesta kinetics and digestive tract content in Manchega and Lacaune dairy sheep in late pregnancy and early and mid lactation

E. Molina

Papers

An integrated sustainability assessment of mediterranean sheep farms with different degrees of intensification

Identification of three single nucleotide polymorphisms in the chicken insulin-like growth factor 1 and 2 genes and their associations with growth and feeding traits

Comparison of carcass composition by parts and tissues between cocks and capons

Determination of fat, protein, and total solids in ovine milk by near-infrared spectroscopy.

Comparison of voluntary food intake, apparent digestibility, digesta kinetics and digestive tract content in Manchega and Lacaune dairy sheep in late pregnancy and early and mid lactation