Figure 1 - Shell breaking force (kg) in various trace mineral treatments.
Shell Breaking Force (49-61 Weeks)
source. Trace minerals in feed are not inert but chemically active and many inorganic sources are highly soluble, disas- sociating during the digestion process. Once the soluble trace metal has separated from its ligand (commonly sulphate) this soluble ion (for example, Cu2
+) can bond with dietary antag-
onists in the feed and in the bird’s gut. Replacing sulphate sources of trace minerals with hydroxy trace minerals can reduce this risk, as hydroxy minerals have a crystalline matrix structure, containing layers held together by covalent bonds which are not reactive or soluble until a pH of less than 4. This design keeps the minerals intact until they reach the proper area within the bird’s gastrointestinal tract. As each trace mineral responds differently to varied antagonists, this may explain an NRC report stating that the absorption coefficients of inorganic trace elements is only 5-20% absorption.
Trace minerals during late lay A study conducted in Australia examined the use of different trace mineral types during late lay. Six hundred 45-week-old laying hens were fed one of two diets and exposed to cycling heat stress. Diets included sulphate-based minerals or hy- droxy minerals. The birds were checked for daily feed intake, FCR, egg production, egg weight and egg mass. Birds receiving the hydroxy trace mineral diet produced eggs with a higher mass, improved feed conversion and better hen-day egg production. Analysis of the heat-stress-related data indicated that use of hydroxy minerals modulated the effects of high temperatures, while birds receiving a sulphate-supplemented diet showed a negative correlation between daily egg production and maximum temperatures. A study conducted at Texas A&M University, tracked 506 birds for 51 weeks, assessing egg production, egg feed conversion, shell thickness and shell strength. Birds were given various diets including a hydroxy mineral control – 60 ppm zinc and 80 ppm manganese – with another treatment looking at the use of an additional 40 ppm zinc and 40 ppm manga- nese from hydroxy sources for weeks 48 to 52. The findings showed that swapping oxide-based minerals for hydroxy minerals improved egg production and egg feed conversion (Figure 1) and, additionally, feeding higher levels of zinc and manganese in the late lay period can significantly improve eggshell thickness and breaking strength (Figures 2 and 3). Extrapolating from the data, just changing the two mineral sources could reduce feed use by 3.4 tonnes for every million eggs produced. Recommended premix nutrient levels (plus energy and macro materials) in laying hens’ diets when aiming to im- prove eggshell quality are presented in Table 1. These are complete levels. An increase in mineral levels is advised when eggshell problems are detected. The dietary levels indicate a 110 g daily intake to be sufficient and can be adjusted when feed intake differs. As the trend towards extended laying phases continues, tailoring trace mineral supplementation to
4,30 4,25 4,20 4,15 4,10 4,05 4,00 3,95
a
b b
Oxide:
60 ppm ZN, 80 ppm Mn
IntelliBond: 60 ppm ZN, 80 ppm Mn
IntelliBond + 40 ppm ZN, 40 ppm Mn week 48-52
Figure 2 - Feed consumed per egg produced (gram) produced by birds fed various trace mineral treatments.
Feed Consumed per Egg (FCR)
110 109 108 107 106 105 104 103
a
b b
Oxide:
60 ppm ZN, 80 ppm Mn
IntelliBond: 60 ppm ZN, 80 ppm Mn
IntelliBond + 40 ppm ZN, 40 ppm Mn week 48-52
Figure 3 - Egg Shell Thickness (mm) produced by birds fed various trace mineral treatments. Feed Consumed per Egg (FCR)
0,427 0,426 0,425 0,424 0,423 0,421 0,420 0,419 0,418 0,417
ab
ab b
Oxide:
60 ppm ZN, 80 ppm Mn
IntelliBond: 60 ppm ZN, 80 ppm Mn
IntelliBond + 40 ppm ZN, 40 ppm Mn week 48-52
optimise availability, implementing split feeding strategies on the farm and assuring best practices for health manage- ment can help producers’ in their efforts to achieve more first- grade eggs, boost the lifetime productivity of their layers and support sustainability by cycling through fewer hens.
▶ POULTRY WORLD | No. 10, 2021 49
mm
gram
Kg
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