Abstract
This study evaluated the influence of a blended phytogenic feed additive on feed intake, feeding behavior, nutrient digestibility, and growth performance during feedlot adaptation, early, and late finishing periods as well as carcass traits. Twenty-six crossbred F1 Angus × Nellore bulls (19 mo ± 4 d) were housed in individually pens and fed a high-forage receiving diet for 7 days. At the end of the receiving period, bulls were weighted [initial shrunk body weight (SBW) 363 ± 20 kg], blocked by SBW and randomly assigned to two treatments; Control: without any additive or PHY: 150 ppm of a phytogenic feed additive fed throughout the adaptation and finishing phases. Bulls were transitioned through four steps over 18 days to a high-grain finishing diet (as % DM, 64% rehydrated corn grain silage, 19% corn gluten feed, 13% sugar cane bagasse and 4% minerals, urea, and vitamins mix). The finishing phase lasted 68 days, with mid-point measurements dividing early and late finishing period. The PHY group DMI was greater during adaptation and late finishing periods (P < 0.05), with a tendency during early finishing period (P = 0.06). Number of daily meals was similar between treatments (P = 0.52), but an increased meal length was noted for PHY group (P < 0.05), which contributed to their greater DMI. Diet digestibility remained similar between groups during the finishing periods (P > 0.1). Ruminitis scores were low and liver abscess similar between treatments. Final SBW tended to be higher (P = 0.09) and hot carcass weight was greater for the PHY group (P < 0.05), with no differences on dressing percentage, ribeye area and marbling score. In conclusion, the PHY treatment had positive effects on intake and carcass weight, without increasing metabolic disorders.
Highlights
Beef production intensification is steeply increasing in Brazil, mainly in the last two decades
During the initial adaptation period, dry matter intake (DMI) of the phytogenic feed additive treatment (PHY) bulls was greater than the Control bulls (P < 0.05, Table 2), with no noted difference in intake variation between the groups
ADiet composition changes during adaptation period are listed in Table 1. bADG, average daily gain. cDMI, dry matter intake
Summary
Beef production intensification is steeply increasing in Brazil, mainly in the last two decades. Among intensification strategies, feeding of high concentrate diets during the finishing phase have been adopted as a tool for shortening the production period and improve meat quality. Challenges include transportation, mixing of animals, introducing new environments and diet transition (Cooke, 2017). Resilience against these challenges is often further compounded by low initial feed intake, contributing to low Phytogenic Feed Additive in Cattle immunocompetence and the occurrence of clinical and subclinical disease, which impact overall performance (Lippolis et al, 2017). Application of phytogenic feed additives (PFA) in animal production has currently received emphasis as a potential alternative to improve performance while meeting consumer desire to reduce none therapeutic pharmaceutical application in the food chain (Runjaic-Antic et al, 2010; ValenzuelaGrijalva et al, 2017). Response to use of phytogenic feed additives for fattening ruminants varies, with reported improvements in feed efficiency (Valero et al, 2014), reduced liver abscess severity, improvements in DMI and ADG (Souza et al, 2019) as well as modulate protein utilization and methane production (Soltan et al, 2018), whereas others have reported no effect on performance (Rivaroli et al, 2017; Michels et al, 2018)
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