Sources of acid insoluble ash as marker of corn digestibility in broilers

The objective was to evaluate three sources of acid insoluble ash (AIA) (celite, kaolin, and sand), as indicators, to determine the apparent metabolizable energy of corn on a natural matter (AME) basis, dry matter digestibility coefficient (DMDC), and crude protein digestibility coefficient (CPDC) using total and partial excreta collection methods. Two hundred and ten Ross broiler chicks of 18 to 27 days of age were used. Broilers were adapted to experimental the diet for four days, and excreta were collected for 5 days. A reference diet (RD) based on corn and soybean meal was prepared to meet the nutritional requirements of the birds. A test diet was prepared with 40% replacement of RD with corn. The formulated diets were: D1, 99% Reference diet + 1% celite; D2, 59.4% RD + 39.6 % corn + 1% celite; D3, 99% Reference diet + 1% kaolin; D4, 59.4% RD + 39.6 % corn + 1% kaolin; D5, 99% Reference diet + 1% sand; D6, 59.4% RD + 39.6 % corn + 1% sand. The treatments were distributed in a completely randomized design, with six diets and five replicates of seven birds each in a 2x3 factorial arrangement. There were significant interactions for all variables investigated. It was observed that the AME and DMDC values of corn were similar in the two methods of collection, and PDC values using kaolin and celite makers were similar. However, the AME and CPDC of corn using sand with partial collection method were underestimated by 17.70 and 15.53%, respectively compared to those with the total collection method. The AME values of corn with the collection methods using celite and, the DMDC using celite and sand were significantly different. It was observed that the DMDC using celite and sand provided significantly lower values (4.67 and 5.15%), respectively, and the AME using celite was 2.86% lower than that obtained by total collection. To determine the EMA, DMDC, and CPDC in broilers, it is more efficient to use celiteTM and kaolin as markers with partial collection of excreta. Sand should not be used with partial excreta collection method, because it provides lower values of AME and CPDC compared to with total excreta collection method.

Predicting Metabolizable Energy from Digestible Energy for Growing and Finishing Beef Cattle and Relationships to Prediction of Methane

Reliable predictions of metabolizable energy (ME) from digestible energy (DE) are necessary to prescribe nutrient requirements of beef cattle accurately. A previously developed database that included 87 treatment means from 23 respiration calorimetry studies has been updated to evaluate the efficiency of converting DE to ME by adding 47 treatment means from 11 additional studies. Diets were fed to growing-finishing cattle under individual feeding conditions. A citation-adjusted linear regression equation was developed where dietary ME concentration (Mcal/kg of dry matter [DM]) was the dependent variable and dietary DE concentration (Mcal/kg) was the independent variable: ME = 1.0001 × DE – 0.3926; r 2 = 0.99, root mean square prediction error [RMSPE] = 0.04, P < 0.01 for the intercept and slope). The slope did not differ from unity (95% CI = 0.936 to 1.065); therefore, the intercept (95% CI = -0.567 to -0.218) defines the value of ME predicted from DE. For practical use, we recommend ME = DE – 0.39. Based on the relationship between DE and ME, we calculated the citation-adjusted loss of methane, which yielded a value of 0.2433 Mcal/kg of DMI (SE = 0.0134). This value was also adjusted for the effects of dry matter intake (DMI) above maintenance, yielding a citation-adjusted relationship: CH4, Mcal/kg = 0.3344 – 0.05639 × multiple of maintenance; r 2 = 0.536, RMSPE = 0.0245, P < 0.01 for the intercept and slope). Both the 0.2433 value and the result of the intake-adjusted equation can be multiplied by DMI to yield an estimate of methane production. These two approaches were evaluated using a second, independent database comprising 129 data points from 29 published studies. Four equations in the literature that used DMI or intake energy to predict methane production also were evaluated with the second database. The mean bias was substantially greater for the two new equations, but slope bias was substantially less than noted for the other DMI-based equations. Our results suggest that ME for growing and finishing cattle can be predicted from DE across a wide range of diets, cattle types, and intake levels by simply subtracting a constant from DE. Mean bias associated with our two new methane emission equations suggests that further research is needed to determine whether coefficients to predict methane from DMI could be developed for specific diet types, levels of DMI relative to body weight, or other variables that affect the emission of methane.

Forage Availability and Quality, and Feeding Behaviour of Indigenous Goats Grazing in a Mediterranean Silvopastoral System

The aim of this study was to study the feeding behaviour of indigenous goats and the selection drivers of different plant species in a Mediterranean forest rangeland. To achieve this goal, the seasonal variations in terms of forage availability and quality of ingested plant species were studied during three grazing seasons. In the same period, eight indigenous goats of Beni Arouss breed were selected to explore the seasonal changes in their browsing behaviour. Forage quality was determined by the hand-plucking technique. The results showed a wide seasonal variation in forage availability and quality, and feeding behaviour. Woody species were more selected independently of the season (p < 0.001). The crude protein content varied from 53.3 g/kg of dry mater (DM) for Erica arborea in summer to 197 g/kg DM for Calicotome villosa in autumn (p < 0.001). Despite the high condensed tannins content in selected shrubs, they were highly consumed. In vitro organic matter digestibility (IVOMD) and metabolizable energy (ME) had recorded the highest contents in herbaceous during spring. Shrubs and trees contain the lowest levels of IVOMD (<500 g/kg) and ME (<7.2 MJ/kg) during autumn and summer. It is concluded that seasonal changes in forage availability and quality did not necessarily affect the indigenous goats’ preference. These findings could help goat herders to develop feeding and grazing systems while increasing the performance of goats in the Mediterranean silvopastoral system.

ESTIMATION OF MEADOW CLOVER VARIETIES IN THE CONDITIONS OF THE MIDDLE URALS

Meadow clover remains the main forage crop in the middle Urals with great potential. An urgent problem is the development and improvement of the technology of this crop cultivation, including the search for adapted varieties. The aim of the research is to estimate the fodder and seed productivity recommended by the originators of meadow clover varieties of Russian and foreign selection VIK 77, Diplo, Lestris, Ranniy 2, Kudesnik in the Middle Ural region. The studies were carried out in 2017-2019 in the forest-steppe zone of the Udmurt Republic on sod-medium-podzolic medium loamy soil. The Dymkovsky variety included in the State Register of Breeding Achievements in the Volga-Vyatka region was used as a standard. Clover varieties were sown in 2017, comprehensive study in 2018-2019. The meteorological conditions of the growing seasons during the study years were different: 2017 and 2019 - over moistened (hydrothermal coefficient – 1.97 and 1.73), 2018 - dry (hydrothermal coefficient – 0.89). Winter hardiness of meadow clover varieties was estimated at 4.5 points. Varieties Diplo, Lestris and Ranniy 2 reached mowing ripeness in 58-63 days, varieties Dymkovsky, VIK 77 and Kudesnik – in 66-70 days. The varieties Diplo, Ranniy 2 and Kudesnik provided a dry matter yield of 6.2-6.8 t/ha, on average for two years of using meadow clover grass-stand. The highest yield of metabolizable energy (51.2 and 55.0 GJ/ha), digestible protein (0.44 and 0.46 t/ha) and feed units (3.79 and 4.09 thousand feed units/ha) was found in the standard variety Dymkovskiy and the tetraploid variety Kudesnik. Seed productivity of cultivars of meadow clover of the 1st year of use was at the level of 137-314 kg/ha, the highest - 314 kg/ha in the standard variety Dymkovsky

Physiological Characters and Alimentary Needs of Both Divergent Lines of the Barbary Partridge (Alectoris barbara, Bonnaterre, 1792) in Algeria

Background: The Barbary partridge (Alectoris barbara) is a wild endemic species of North-Africa. The lack of information about this species, allows putting research focus in the hunting center of Zeralda, on the selection of a line for an improvement on the zootechnical characteristics of this population. Methods: Over 13 weeks of follow-up, we have performed weekly measurements on 3 successive generations F12-F14 with daily measurements of food intake. We are interested at the fundamental level of the biological characterization of both divergent lines. The analysis of the effects of selection pressures on the growth to estimate the metabolizable energy of each line. Result: During 273 days of study period, we noticed that the metabolizable energy has an average divergence between the fast line and the slow one with 0.328 Kcal/day since birth and an average divergence of 8.899 Kcal/day towards the 13th week in favour of the fast line. Significance noticed between males and females with a favour of the males which are more important. In addition to that, the values of weight-based consumption index imply higher indices for the slow line compared to the values of the fast line. Our results highlight the efficiency of the selection scheme. This progress will allow developing the restoration methods and/or the natural restocking populations on scientific bases.

Validating dietary assessment tools with energy expenditure measurement methods: Is this accurate?

Having an accurate dietary assessment tool is a necessity for most nutritional studies. As a result, many validation studies have been carried out to assess the validity of commonly used dietary assessment tools. Since based on the energy balance equation, among individuals with a stable weight, Energy Intake (EI) is equal to Energy Expenditure (EE) and there are precise methods for measurement of EE (e.g. doubly labeled water method), numerous studies have used this technique for validating dietary assessment tools. If there was a discrepancy between measured EI and EE, the researchers have concluded that self-reported dietary assessment tools are not valid or participants misreport their dietary intakes. However, the calculation of EI with common dietary assessment tools such as food frequency questionnaires (FFQs), 24-hour dietary recalls, or weighed food records, is based on fixed factors that were introduced by Atwater and the accuracy of these factors are under question. Moreover, the amount of energy absorption, and utilization from a diet, depends on various factors and there are considerable interindividual differences in this regard, for example in gut microbiota composition. As a result, the EI which is calculated using dietary assessment tools is likely not representative of real metabolizable energy which is equal to EE in individuals with stable weight, thus validating dietary assessment tools with EE measurement methods may not be accurate. We aim to address this issue briefly and propose a feasible elucidation, albeit not a complete solution.

Productivity of natural phytocenoses of the Namsky agrolandscape in Yakutia under organic and mineral nutrition regimes

The results of the study of the productivity potential of natural phytocenoses of different species composition in the Namsky agrolandscape of the middle taiga subzone of the Republic of Sakha (Yakutia) are presented. The research was conducted in 2009-2016. The soils of the experimental plot are permafrost soils with a thin humus layer. The effect of mineral and organic fertilizers on the productivity of steppe meadows was studied. On herb-grass, wheatgrass, steppificated phytocenoses the following practices of organo-mineral nutrition of plants were used: control (no fertilizer); humus 20 t/ha; humus 20 t/ha once every 4 years + N60P60K60 annually; N30P30K30 annually; humus 20 t/ha annually. The optimum rates of organic and mineral nutrients to improve the productivity potential of natural steppe meadows have been established. The highest productivity potential in the Namsky agrolandscape was obtained with the combined application of organic and mineral fertilizers (humus 20 t/ha once every 4 years + N60P60K60 annually). On herb-grass and wheatgrass phytocenoses hay yield reached 23.0-24.1 c/ha. Yield per 1 ha of metabolizable energy was 27.0-22.4 GJ, fodder units 1472-1663, crude protein 336-371 kg. The content of digestible protein in 1 fodder unit in herb-grass was 92 g, in wheatgrass - 102 g. The annual application of mineral fertilizers at a dose of 60 kg/ha of the active substance provided a 2-fold increase in the productivity of natural phytocenoses, depending on agroclimatic conditions of the growing season. The influence of mineral fertilizers and their joint application with organic fertilizers on the yield of natural phytocenoses is statistically reliable, which indicates the possibility of regulating the productivity of steppificated phytocenoses.

Productive Performance of Mexican Creole Pullets and Immature Males Fed Different Levels of Metabolizable Energy and Crude Protein

Mexican Creole birds are a poorly researched genetic resource whose nutritional requirements are unknown. The objective was to evaluate the productive performance and nutrient use efficiency of Mexican Creole birds, using four diets with different concentrations of metabolizable energy (EM, MJ/kg) and crude protein (PC, g/kg). The experimental diets with constant ME/CP ratios equal to 0.06, were: 12.55/200, 11.92/190, 11.30/180 and 10.67/170. One hundred and ninety-two 12-week-old creole birds (96 males and 96 females) were randomly distributed amongst the diets (24 males and 24 females each). Due to the diet × sex interaction, males fed the 10.67/170 diet had higher feed intake, and males under 10.67/170, 11.92/190 and 11.30/180 had higher final body weight and weight gain than the other birds. Feed conversion ratio was lower in birds with diets 12.55/200 and 11.92/190. Total body fat retention was higher in females with the diet 12.55/200, 11.92/190 and 11.30/180. In conclusion, males with the 10.67/170 (lowest ME and CP) diet showed a high productive performance, without compromising carcase yield and body composition, while females with all diets did not show differences in productive performance, carcass yield and body composition.

Lipid profile of subcutaneous fat, growth performance, and carcass characteristics of gilts fed with diets supplemented with ractopamine, organic chromium or subjected to energetic feed restriction

ABSTRACT: This study identified the effects of dietary supplementation with ractopamine, chromium picolinate, chromium yeast, or an energetic feed restriction on the growth performance and lipid profile of subcutaneous fat, in late finishing gilts. Twenty genetically similar gilts with initial body weight of 105.35 ± 4.77 kg and a final body weight of 131.37 ± 5.58 kg were distributed in a completely randomized block design with five treatments (control; ractopamine: 20 ppm; chromium picolinate: 0.48 ppm; chromium yeast: 0.80 ppm; and energetic feed restriction: -150 kcal kg-1 of metabolizable energy), with four replicates of one animal each. The experimental diets were isonutritives, except for the metabolizable energy level of the diet fed to the group subjected to energy restriction. There were no effects on the growth performance and carcass characteristics. Ractopamine and organic chromium (picolinate and yeast) supplementation increased the concentration of total polyunsaturated fatty acid. The proportion of α-linolenic fatty acids were higher when the diets were supplemented with ractopamine or chromium yeast. The energy restriction increased the n-6:n-3 ratio and reduced α-linolenic acid concentration. Therefore, ractopamine, chromium picolinate, chromium yeast supplementation, and energetic feed restriction did not affect the growth performance or carcass characteristics but altered the lipid profile of subcutaneous fat in finishing gilts. Ractopamine and organic chromium supplementation increased PUFA in the fat of finishing female pigs.

AGRO-ENERGY EFFICIENCY OF CREATION AND LONG-TERM INTENSIVE USE OF EARLY- AND MEDIUM-RIPENING CEREALS GRASS STANDS

The agro-energy assessment showed the high efficiency of the creation and long-term three-mowing use of cereal grass stands. The collection of metabolizable energy on agrocenoses of different ripening was 58–69 GJ/ha on average over 27 years. In the structure of its production, the main part (60–66%) is provided by natural factors.