Year: 2026
Type: article
Abstract: A multi-study approach was employed to develop predictive models of nitrogen urinary, fecal, and total excretion, using dry matter intake (DMI), nitrogen intake (NI), and total digestible nutrient intake (TDNI) as predictor variables. Databases were obtained from 18 studies, totaling 380 observations; there were 3 sex classes (223 intact, 77 castrated males, and 80 females) of hair sheep in a feedlot from 10.3 to 48.8 kg body weight (BW). The most representative genotypes in the database were Santa Ines (n = 236), followed by crossbreed Santa Ines x Dorper (n = 66), Brazilian Somali (n = 45), Dorper (n = 24), and Morada Nova (n = 9). Correlation analysis was conducted to identify the parameters associated with urinary and fecal nitrogen excretion. The effects of sex and genotype were tested on the parameters of all models, and equivalence among the different sex classes and genotypes was observed, resulting in general models. The validation was performed using the Model Evaluation System. Linear models generated to estimate FN from the dry matter intake (DMI, g/day), nitrogen intake (NI, g/day), are as follows: FN = - 0.07745 (± 0.757) + 0.006592 (± 0.001) × DMI; FN = 0.8852 (± 0.655) + 0.2495 (± 0.033) × NI. Nonlinear models were adjusted to estimate UN against NI: UN = 1.8324 (± 0.824) × exp 0.03831 (± 0.008) × NI. For estimating TN, exponential model was developed using NI as a predictor variable: TN = 6.0720 (± 0.802) × exp 0.02736(± 0.002) × NI. The validation suggests that the models accurately predict the nitrogen excretion, however the model based on NI showed the best performance. Models generated for estimating N excretion by feedlot hair sheep presented superior performance for fecal N (CCC = 0.82; RMSEP = 1.63 g/day), moderate for total N (CCC = 0.69 and 0.73; RMSEP 4.40 and 3.63 g/day), however with low precision and accuracy for Urinary N (CCC = 0.36 and 0.49; RMSEP = 4.44 and 3.30 g/day). In conclusion, the models generated to predict N excretion in hair sheep support feedlot feeding systems showed good performance for fecal N excretion, moderate performance for total N, and lower accuracy for urinary N.
Source: Frontiers in Animal Science
Authors: Ana Jullya Costa Clarindo, Antonio Sousa Brito Neto, Aderson Martins Viana Neto, Vitoria Fátima Costa Araujo, Luiz Wilker Lopes Silva, Caio Julio Lima Herbster, Francisco Gleyson Silveira Alves, Aníbal Coutinho Rego, Arlindo Alencar Araripe Noronha Moura, Marcelo Andrade Ferreira, Greicy Mitzi Bezerra Moreno, Ronaldo Lopes Oliveira, Leilson Rocha Bezerra, Alfonso Juventino Chay-Canul, Evandro Maia Ferreira, Stefanie Alvarenga Santos, Elzania Sales Pereira
Institutions: Universidade Federal do Ceará, Universidade Federal de Viçosa, Universidade Estadual Paulista (Unesp), Universidade Federal do Piauí, Universidade Federal Rural de Pernambuco, Universidade Federal de Alagoas, Universidade Federal da Bahia, Universidade Federal de Campina Grande, Universidad Juárez Autónoma de Tabasco, Universidade de São Paulo
Language: English
Subfield: Animal Science and Zoology
Domain: Life Sciences
SDG: Zero hunger
Open Access status: gold
Estimated APC paid: $2,353
Awards: G1232768090, G7156289940
OpenAlex ID: W7223138941