Effects of dietary supplementation on ingestive behavior and consumption of grazing sheep: a systematic review.

Abstract

This study aimed to summarize the main information from published studies on the effects of dietary supplementation on the ingestive behavior and consumption of grazing sheep and to support efficient feeding strategies. The guiding question formulated based on the PICOS strategy was: Does dietary supplementation influence the ingestive behavior and voluntary forage consumption of sheep kept on pasture? Four databases were used: SCOPUS (Elsevier), Web of Science (main collection), Science Direct (Elsevier), and CAB Direct, and the search was carried out from January to July 2023. Only complete research articles, available in full, well-designed, and published in any language, with no time frame, were considered. A total of 8,132 documents were retrieved and after applying the eligibility criteria, 7 were considered eligible and included in the final sample. 28.6% evaluated ingestive behavior for 24 uninterrupted hours, 28.6% for 12 h, 14.3% for 11 h, and 28.6% for 9 h evaluated. The interval for observing behavior was every five minutes for 42.9% and every 10 min for 57.1% of the studies. The studies that evaluated grazing, rumination, and idle time, only 14% evaluated supplement intake time and water drinking time, 43% evaluated the bite rate, and 29% the bite mass. Among the methods for estimating dry matter intake (DMI), the most used were chromium oxide and titanium dioxide (42.5% each), and the estimate by formula corresponded to 14.29%. It was observed that 57.14% of the studies were published in national journals, the most used animal breed was Santa Inês (42.85%), and the most evaluated grazing method was continuous (57.14%). The use of supplementation, as well as the different levels and types of ingredients, influenced the ingestive behavior and voluntary dry matter intake of grazing sheep. By increasing the level of supplementation, the substitutive associative effect of the animals also increases the consumption of the supplement to the detriment of the pasture. Providing concentrated supplements with ingredients that have lower fiber content and higher TDN alters ingestive behavior, with a decrease in grazing and rumination time and an increase in idle time.