ISSUE FOCUS 36 FEED & ADDITIVE MAGAZINE November 2023 According to Nording and Capling (1979), the differences in the apparent digestibility of grains between species may be related to the physical size of the reticulo-omasal orifice, which is considerably greater in cattle than in sheep or goats. In cattle, unmasticated whole grains, which are those still resistant to enzyme attacks, can pass from the reticulo-rumen into the abomasum. Whereas in sheep or goats, similar grains are retained within the reticulo-rumen and subjected to further mastication during rumination, which results in rupture of the seed coat of most of the cereal grains so enzyme degradation can occur. This makes lambs more susceptible to rumen acidosis since they will have a higher amount of starch fermentation. Affected lambs usually show a lack of appetite, depression, weakness, and a soft or watery scour. All these symptoms have a direct effect on performance, and animals with acidosis will have a lower average daily gain and a higher feed conversion rate. Furthermore, too much degradable starch in the rumen produces more propionate leading to less biohydrogenation of fats and more iso-fatty acids, which can impact the fat composition of the carcass (soft fat, taste alteration on the meat, etc.). Sub-acute rumen acidosis is a common situation in lamb feedlots with an impact on the health of the animals, their performance, and carcass quality. PHYTOGENIC FEED SOLUTIONS IN LAMB PRODUCTION Besides good management and a well-balanced diet, one of the best methods to optimize intake, reduce feed costs, and improve feed efficiency of feedlot lambs is through the use of phytogenic feed additives. Substances like saponins, essential oils, and spices have been shown to improve feed efficiency and, therefore, performance in lambs. In our research, Actifor™ Power ingredients have been shown to reduce starch concentration in feces when compared to the control diet (Table 1), which suggests optimized intestinal starch digestion and improved bypass starch utilization. This can result in improved energy efficiency of lamb diets. The unique formulation of Actifor™ Power has been shown to help reduce starch degradation rate in the rumen (Delacon internal in vivo trial) and stimulate saliva production (INRA trial 2016). These two actions combined may contribute to stabilizing the physiological conditions of the rumen (Table 2). Control Actifor® Power Feces consistency score(1) Fibers presence score(2) Sieve residue (%) Starch in feces (g/kg DM) 3.3 3.8 37.5 1.99 2.8 3.6 29.0 1.82 Table 1. Observed effects of feeding Actifor™ Power on fiber and starch digestibility (Delacon in vivo trial, Germany 2015) (1)1 liquid à 5 hard (2)1 short à 5 long Control group Actifor™Power group Actifor™Power effect P – value pH average pH min Time spent < 5.6 (min) 5.85 4.94 416.5 5.86 5.25 379.8 +0.01 +0.31 -36.7 NS P<0.1 P<0.1 Table 2. Effect of Acifor™ Power on rumen pH (Delacon internal in vivo trial, NED 2020)
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