The effect of grazing intensity and supplementation on performance, stress indicators and metabolic profiles of finishing lambs

Abstract

In the present study, the effect of grazing intensity (GI) and feed supplementation in sixty-four crossbred Santa Inês lambs was assessed based on performance, blood stress indicators, and metabolic profiles. The GIs analyzed were VH = very high, H = high, L = low, and VL = very low, and were represented by the residual leaf area index (LAIr). The lambs were divided into two groups, supplemented (SP) and non-supplemented (NSP). The dry matter intake (DMI) and average daily gain (ADG) increased linearly with decreasing GI (P < 0.05), and the ADG was higher for the NSP group than the SP group (P < 0.05). The plasma cortisol concentration was higher in the NSP group (P < 0.05), and it was not affected by GIs (P > 0.05). The neutrophil:lymphocyte (N:L) ratio decreased linearly with GI (P < 0.05), and the SP group had a higher N:L ratio (P < 0.05). None of the parameters evaluated for protein metabolism were affected by GI (P > 0.05), except albumin, where the SP group had a higher concentration of this metabolite (P < 0.05). Regarding energy metabolism indicators, glucose showed a linear increase with a decrease in GI (P < 0.05) and was higher in the SP group (P < 0.05); however, there was a decreasing linear effect (P < 0.05) and the NSP group had higher serum levels (P < 0.05) of non-esterified fatty acids (NEFA). The concentration of beta hydroxybutyrate (HBA-B) was higher in the SP group (P < 0.05). The concentration of calcium was affected by GI (P < 0.05). The phosphorus concentration was higher in the SP group (P < 0.05), and concentration of magnesium was not affected by any of the treatments (P > 0.05). It was concluded that GI and SP modified the performance, stress indicators, and metabolic profiles of finishing lambs. Key words: Blood parameters, cortisol, energy metabolism, ovine, pasture, protein metabolism ResumoNo presente estudo foi avaliado o efeito de intensidades de pastejo (IP) pelo índice de área foliar residual (IAFr). Onde, 0,8; 1,4; 2,0 e 2,6 de IAFr corresponde a MA= muito alto, A= alto, B= baixo e MB= muito baixo com suplemento (SP) ou não suplementado (NSP) no desempenho, indicadores de estresse e perfil

Low-Intensity, High-Frequency Grazing Positively Affects Defoliating Behavior, Nutrient Intake and Blood Indicators of Nutrition and Stress in Sheep

“…Glucose concentration in both RN and RT sheep (Table 4) is within reference values of adult sheep (31), and values in RN animals compare well with those of sheep grazing ryegrass at low intensity (49). Moreover, other reports coincide with this study in that animals with restricted feed intake, thus with limited supply of gluconeogenic substrates, have lower blood glucose concentration than better feed animals (50)(51)(52)(53).…”

“…In this latter regard, energy intake restriction reduces cholesterol levels (57), triggers the mobilization of fatty acids from adipocytes and increases the serum concentration of NEFA (47), limits propionate production (58) and stimulates the synthesis of ketone bodies, mainly BHB (59,60). In this study, cholesterol and BHB blood concentrations were within values previously reported for sheep (49,52), but lower than values reported by Kaneko et al (31) for BHB; however, as the grazing management did not affect their concentration on nonmetabolically challenged adult sheep, we suggest that substantial changes of these energy metabolites are more likely to occur when imposing energy intake restrictions below maintenance (50), which was not the case of our study, as animals of both treatments put on weight (data not shown), as demonstrated by Schons et al ( 9) in a similar experiment. Likewise, alkaline phosphatase can be reduced under feed intake restriction, as occurred with sheep at a high stocking rate (61).…”

“…This is also suggested from the greater NEFA concentration, as animals with high circulating NEFA can have their immune system suppressed (Ingvartsen and Moyes, 2012). A greater N:L ratio (52) or the expression of hepatic proteins involved in immune response and inflammatory cytokines (53), as indicators of welfare impairment were also observed on sheep under sub-optimal grazing conditions.…”

Anatomical, morphogenic and structural characteristics of Xaraés palisade grass under grazing

“…The rLAI values were chosen based on previous experiments conducted by the research group in pastures of Tifton 85 (Cynodon spp.) (Silva et al 2013;Costa et al 2015;Silva et al 2016a;Silva et al 2019) and Xaraés palisadegrass (Raposo et al 2014;Galzerano et al 2015) in order to cover an amplitude that represented different grazing intensities. The rLAI was monitored during the grazing period through measurements taken in each paddock, and once the rLAI was achieved, animals were moved to another paddock where the pasture had intercepted 95% of light (LI) during the regrowth period.…”