Banca de DEFESA: CAIO CÉSAR CARNEIRO DOS SANTOS

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : CAIO CÉSAR CARNEIRO DOS SANTOS
DATE: 03/02/2026
TIME: 08:00
LOCAL: Departamento de Zootecnia
TITLE:

Replacing corn silage with forage cactus (Opuntia stricta (Haw) Haw.) plus sugarcane bagasse and urea in the diet of sheep.

KEY WORDS:

Forage - Neutral detergent fiber - rumen - nutrition

PAGES: 120
BIG AREA: Ciências Agrárias
AREA: Zootecnia
SUBÁREA: Nutrição e Alimentação Animal
SPECIALTY: Avaliação de Alimentos para Animais
SUMMARY:

The objective of this study was to evaluate how replacing corn silage with forage cactus (Opuntia stricta (Haw.) Haw), sugarcane bagasse, and urea affects dry matter intake, potentially digestible dry matter (PDDM), digestibility, ruminal pH, nitrogen compound utilization efficiency, microbial protein synthesis, ingestive behavior, and ruminal activity in sheep, while maintaining constant neutral detergent fiber (NDF) levels. Five different levels of substitution (0, 25, 50, 75, and 100%) were tested using five rumen-fistulated and rumen-cannulated male Santa Inês sheep (body weight 37.5 ± 5.57 kg) in a 5 × 5 Latin square design. As a result, dry matter (DM), ash- and protein-corrected NDF (NDFcp), and total digestible nutrient (TDN) intake decreased linearly with the substitution level (P < 0.03, P < 0.02, and P < 0.01, respectively), while indigestible NDF intake increased linearly (P < 0.04). The apparent digestibility of DM, organic matter (OM), and NDF in the diet also showed a linear decline (P < 0.01 for all variables). A linear increase was observed in the ruminal pool of NDFi (P < 0.01) and in the retention time of NDFcp (Tr) (P < 0.01). On the other hand, the ruminal pool of potentially digestible NDF (NDFpd), as well as the passage (kp) and degradation (kd) rates of NDFcp, decreased (P < 0.01 for all variables). Conversely, replacing corn silage with a mixture of palm, sugarcane bagasse, and urea did not affect feed efficiency for DM and NDFcp; however, rumination efficiency for DM and NDFcp decreased (P < 0.02 and P < 0.01, respectively). Ruminal pH was not affected by the substitution (6.2 ± 0.04). Ruminal ammonia nitrogen (RAN) increased linearly with replacement levels (15.10–19.08 mg/dL; P <0.034), with an interaction between levels and collection time, showing higher RAN peaks as the replacement level increased (19.00–27.12 mg/dL; P <0.01). On the other hand, nitrogen intake, fecal nitrogen, retained nitrogen (g/day and as a percentage of intake), and microbial protein synthesis decreased with increasing replacement levels (P <0.04, P <0.02, P <0.03, and P <0.01, respectively). In contrast, urinary nitrogen as a percentage of intake and blood urea nitrogen increased linearly (P < 0.03 and P < 0.01, respectively). The results of this study suggest that maintaining NDF fixed at 45% of DM in diets with increasing replacement of corn silage with OEM palm and sugarcane bagasse plus urea may not be a viable approach. This limitation stems mainly from the need to include progressively larger amounts of sugarcane bagasse to achieve the desired NDF level, which substantially increases the proportion of NDFi in the fibrous fraction of the diet, negatively affecting TDN intake by the animals. Therefore, it can be concluded that the combination of forage palm, sugarcane bagasse, and urea did not adequately replace corn silage, as it reduced the passage and degradation rates of NDFcp in the rumen, increasing retention time and consequently reducing nutrient intake, in addition to decreasing the efficiency of nitrogen compound utilization and limiting microbial protein synthesis in the rumen. It is recommended to consider not only the total NDF content in formulating diets for sheep, but also the levels of NDFi and NDFpd.

COMMITTEE MEMBERS:
Presidente - MARCELO DE ANDRADE FERREIRA
Interna - KELLY CRISTINA DOS SANTOS
Interno - VALDSON JOSE DA SILVA
Externa ao Programa - 2234529 - LUCIANA FELIZARDO PEREIRA SOARES - UFRPEExterna à Instituição - JUANA CATARINA CARIRI CHAGAS
Externa à Instituição - MARIA GABRIELA DA CONCEICAO - UFCA
Externa à Instituição - STELA ANTAS URBANO - UFRN