Dorper × Santa Ines F1 crossbred lambs under different grazing times and supplement levels in tropical regions: performance and macromineral requirements

Abstract

The objective of this study was to evaluate the performance and net requirements for calcium (Ca), phosphorus (P), magnesium (Mg), potassium (K) and sodium (Na) in Dorper  Santa Ines F1 crossbred lambs under different grazing times and supplement levels. We used 36 uncastrated male lambs with initial body weights (BW) of 15.5 ± 1.9 kg. Twelve animals were used as a reference group, and the remaining 24 animals were divided into three treatments according to grazing time and supplement level: 9 h  1.2% BW, 6 h  0.84% BW and 3 h  0.48% BW. There were increases in the final BW, average daily gain (ADG) and dry matter intake (DMI) of pasture (p < .05) in lambs that grazed longer (9 h  1.2% BW). Feed efficiency (G/F ratio) was similar between the 9 h  1.2% BW and 6 h  0.84% BW groups and both the groups were greater than the 3 h  0.48% BW. However, there was a reduction in the DMI of concentrate, total DMI, and Ca, P, Mg and K intake (p < .05) for lambs that grazed longer. However, pasture DMI and sodium intake increased (p < .05) in animals that grazed for less time (3 h). The chemical composition of the empty bodies in DM, fat, ash, Ca and P showed the greatest values (p < .05) in groups with animals grazing 9 h with a supplement level of 1.2% BW. Net maintenance requirements were 0.101-0.202 g Ca/day, 0.204-0.408 g P/day, 0.053-0.105 g Mg/day, 0.386-0.771 g K/day and 0.105-0.211 g Na/day for crossbred lambs between 15 and 30 kg BW. For the same group, net requirements to gain 100/200 g/day BW were 1.171/2.341-1.667/3.333 g Ca/day, 0.694/ 1.398-0.998/1.995 g P/day, 0.027/0.054-0.032/0.063 g Mg/day, 0.098/0.195-0.091/0.182 g K/day and 0.315/0.629-0.311/0.621 g Na/day. Lambs grazing longer (9 h  1.2% BW) displayed increased ADG and concentrate intake and reduced forage intake, which increased intake and body retention of Ca, P, Mg and K.ARTICLE HISTORY

Mineral requirements for weight gain in growing male Santa Inês and Morada Nova hair sheep

“…The value advocated by this committee is not in accordance with the needs of animals raised in tropical conditions, and enhanced levels of recycling of these nutrients may occur in animals raised under these conditions. This observation has also been reported by Assis et al (2018). Trace mineral requirements vary during stages of growth due to changes in the metabolic needs of individual tissues (Masters et al, 1999).…”

“…Results obtained for Santa Inês and Morada Nova sheep revealed that both breeds contained lower percentages of Ca (7.33% and 11.7%, respectively) and greater percentages of P (13.6% and 7.28%, respectively) than values reported by AFRC (1991) and ARC (1980) and that Ca and P percentages were similar to those observed by Assis et al (2018), who also worked with Santa Inês sheep, which were allowed to graze on vegetation of the Caatinga Biome. The ARC (1980) committee recommended that 1.5 g/d Ca and 0.7 g/d of P be provided per 100 g BW gain.…”

“…Decreased copper, zinc, and iron concentrations, which occurred as EBW increased, were also observed by Mendes et al (2010) and Assis et al (2018), who performed studies using Santa Inês sheep. Body compositions of copper, iron, and zinc microminerals ranged from 10.8 to 16.7 mg Cu, 133 to 127 mg Fe, and 60.3 to 76.4 mg Zn per kg EBW, in animals with live weights of 20 and 30 kg, respectively.…”

“…GonzagaNeto et al (2005) assessed Morada Nova animals weighing between 15 to 25 kg, and K and Na values determined in this study were lower than those determined for animals previously. This is likely because the animals used in the previous study had a lower percentage of fat, which resulted in proportional increases in EBW mineral levels.Decreased copper, zinc, and iron concentrations, which occurred as EBW increased, were also observed byMendes et al (2010) andAssis et al (2018), who performed studies using Santa Inês sheep.Body compositions of copper, iron, and zinc microminerals ranged from 10.8 to 16.7 mg Cu, 133 to 127 mg Fe, and 60.3 to 76.4 mg Zn per kg EBW, in animals with live weights of 20 and 30 kg, respectively. The varying concentrations determined were likely a result of the nutritional management of animals studied, which include mineral and vitamin supplementation to the diets of animals.…”

“…Animals of different genotypes possess different nutritional requirements due to differences in their body compositions (Pereira et al, 2017; Teixeira et al, 2015). These differences result from a combination of genetic environmental conditions in which phenotypic expression of a given genotype (Wiseman & Mahan, 2010) and knowledge of these requirements contribute to the adaptability of animals and facilitate the adoption of management practices such as concentrated and mineral supplementation, which directly influence the weight at which the animals can be slaughtered and marketed (Assis et al, 2018; Costa et al, 2018).…”