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Context. Early weaning is an alternative that may shorten the production time, and improve growth, and carcass quality. Aims. The effects of different weaning ages on growth performance and carcass characteristics of Dorper × Santa Inês lambs were evaluated. Methods. Initially, 33 crossbred lactating ewes Dorper × Santa Inês with initial bodyweight (BW) of 53.16 ± 9.17 kg (mean ± s.d.) were penned individually with their lambs (nine females and 36 males; 6.59 ± 0.30 kg of initial BWand 10 ± 2.22 days of age) 10 days after birth and used in a randomised complete block design (three treatments and 11 blocks). Each pen was individually equipped with a creep feed system for the lambs. The lambs received the initial diet, and the ewes were confined and received a diet with 400 g/kg of roughage and 600 g/kg of concentrate. Lambs were weaned at ages of either 45 days (W45), 60 days (W60) or 75 days (W75). At weaning, the ewes were removed from the pens and the lambs remained in the same pen for 15 days, receiving the initial diet. After 15 days of weaning, only the males continued received the finishing diet until 165 days of life. After the finishing period, the lambs were slaughtered to measure the carcass characteristics. Key results. There was no influence of weaning age on BW, body condition score, dry-matter intake, and milk production and composition of ewes. Additionally, there was no effect of treatments on the lambs' performance. Conclusion. In an intensive production system, weaning at 45, 60, and 75 days provided similar growth performance and carcass characteristics. Implications. Therefore, weaning at 45 days may be an option for farmers. [ABSTRACT FROM AUTHOR]

Context. Ionophores improve rumen fermentation efficiency, average daily gain (ADG) and feed efficiency. However, the effects of providing ionophores to grazing animals are extremely variable, primarily due to infrequent supplement intake. Aim. This study aimed to evaluate the effect of frequency of narasin intake on ruminal fermentation, nutrient digestibility and growth of lambs. Methods. In Experiment I (metabolism assay), four rumen-cannulated wethers (1/2 Dorper × 1/2 Santa Inês) were assigned to a 4 × 4 Latin square design. The four treatments included a control, where animals were fed a diet without ionophore, and the following three treatments where animals were fed narasin at different intervals: 13 mg/kg of narasin every 24 h (N24), 26 mg/kg of narasin every 48 h (N48) and 39 mg/kg of narasin every 72 h (N72). All animals were fed with 95% Tifton-85 hay and 5% ground corn that was used as a vehicle for narasin. In Experiment II, 44 lambs (1/2 Dorper × 1/2 Santa Inês; 33.3 ± 0.5 kg (mean ± s.e.m.) and 180.5 ± 8 days of age) were used in a randomised complete-block design to assess performance. All treatments and management were similar to those in Experiment I. Key results. Experiment I, dry-matter intake and apparent digestibility of nutrients were not affected by the treatments. The treatments N24 and N48 increased (P < 0.01) the total molar concentration of short-chain fatty acids compared with control and N72, and increased (P < 0.01) the concentration of propionate compared with control. In Experiment II, the treatments N24 and N48 increased the liveweight gain (P = 0.03) and feed efficiency (P = 0.02) compared with control and N72. Conclusion. Effectiveness of narasin was reduced when offered at intervals greater than 48 h. Implication. Frequency of narasin intake affects lamb production, and feeding systems are required where animals consume supplements on a regular basis. [ABSTRACT FROM AUTHOR]

Two trials were conducted to determine net protein requirements and the use of metabolizable protein (MP) for growing ram lambs when fed diets with different concentrate levels and roughage quality. In a comparative slaughter trial, eighty-four ½ Dorper × ½ Santa Inês ram lambs (18.0 ± 3.3 kg of BW) were individually penned and divided into 2 diet groups differing in roughage source: low-quality (sugarcane bagasse) roughage (LQR) or medium-quality (coastcross hay) roughage (MQR). In each group, 7 lambs were randomly selected and slaughtered after a 10 days adaptation period (baseline). Other 21 lambs from each diet group were fed ad libitum and slaughtered at 25, 35, or 45 kg of BW, and the remaining 28 lambs (14 from each diet group) were submitted to 1 of 2 levels of feed restriction (70 or 50% of the ad libitum intake). Body N content and retention were determined. In the second trial, 6 ram lambs (44.3 ± 5.6 kg of BW) were kept in metabolic cages and used in a 6 × 6 Latin square experiment designed to determine N digestibility and microbial N synthesis, and to compute MP supply by the 2 diets and 3 levels of intake. Nitrogen intake and microbial N synthesis were greater for the animals fed the MQR diet than for those fed the LQR diet ( P  < 0.05). Neither the endogenous and metabolic N losses, nor the net protein requirements for growth differed between diets ( P  > 0.05). However, the proportion of MP used for both maintenance and growth was lower for the animals fed the MQR diet ( P <  0.05), likely because of an excess of MP reaching duodenum of these animals. We concluded that a reduction of the concentrate level in diets for growing ram lambs, achieved by improving the quality of the diet roughage, allows a greater supply of MP and may contribute to reduce diet protein concentration. [ABSTRACT FROM AUTHOR]

Nitrate can be a source of NPN for microbial growth at the same time that it reduces ruminal methane production. The objective of this study was to evaluate the effects of 2 encapsulated nitrate products used as urea replacers on blood and rumen constituents, methane emission, and growth performance of lambs. Eighteen Santa Inês male lambs (27 ± 4.9 kg) were individually allotted to indoor pens and assigned to a randomized complete block design with 6 blocks and 3 dietary treatments: control (CTL) = 1.5% urea, ENP = 4.51% encapsulated nitrate product (60.83% NO3- in the product DM), and ENP+CNSL = 4.51% ENP containing cashew nut shell liquid (60.83% NO3- and 2.96% cashew nut shell liquid [CNSL] in the product DM). Diets were isonitrogenous with 60:40 concentrate:forage (Tifton 85 hay) ratio. The experiment lasted for 92 d and consisted of 28 d for adaptation (a weekly 33% stepwise replacement of CTL concentrate by nitrate-containing concentrates) and 64 d for data collection. The ENP and ENP+CNSL showed greater (P < 0.05) red blood cell counts than CTL. Blood methemoglobin (MetHb) did not differ (P > 0.05) among treatments, with mean values within normal range and remaining below 1.1% of total hemoglobin. There was an increase (P < 0.05) in total short-chain fatty acids concentration at 3 h postfeeding for ENP, with an additional increase (P < 0.05) observed for ENP+CNSL. No treatment effects (P > 0.05) were observed on acetate to propionate ratio. Methane production (L/kg DMI) was reduced (P < 0.05) with nitrate inclusion, recording 28.6,19.1, and 19.5 L/kg DMI for CTL, ENP, and ENP+CNSL, respectively. Addition of CNSL did not result (P > 0.05) in further reduction of methane production when compared with ENP. Final BW, DMI, ADG, and feed efficiency were similar (P > 0.05) among treatments. Values for DMI were 1.11, 1.03, and 1.04 kg/d and for ADG were 174, 154, and 158 g for CTL, ENP, and ENP+CNSL, respectively. In conclusion, encapsulated nitrate products showed no risks of toxicity based on MetHb formation. The products persistently reduced methane production without affecting performance. Inclusion of cashew nut shell liquid in the product formulation had no additional benefits on methane mitigation. [ABSTRACT FROM AUTHOR]

Poor-quality roughages are widely used as fiber sources in concentrate-based diets for ruminants. Because roughage quality is associated with the efficiency of energy use in forage-based diets, the objective of this study was to determine whether differing the roughage source in concentrate-based diets could change the energy requirements of growing lambs. Eighty-four 1/2 Dorper × 1/2 Santa Inés ram lambs (18.0 ± 3.3 kg BW) were individually penned and divided into 2 groups according to primary source of dietary roughage: low-quality rough-age (LQR; sugarcane bagasse) or medium-quality rough-age (MQR; coastcross hay). Diets were formulated to be isonitrogenous (2.6% N) and to meet 20% of physically effective NDF. After a 10-d ad libitum adaptation period, 7 lambs from each group were randomly selected and slaughtered (baseline). Twenty-one lambs in each diet group were fed ad libitum and slaughtered at 25, 35, or 45 kg BW. The remaining 28 lambs (14 from each diet group) were submitted to 1 of 2 levels of feed restriction: 70% or 50% of the ad libitum intake. Retentions of body fat, N, and energy were determined. Additionally, 6 ram lambs (44.3 ± 5.6 kg BW) were kept in metabolic cages and used in a 6 × 6 Latin square experiment designed to establish the ME content of the 2 diets at the 3 levels of DM intake. There was no effect of intake level on diet ME content, but it was greater in the diet with LQR than in the diet with MQR (3.18 vs. 2.94 Mcal/kg, respectively; P < 0.01). Lambs fed the diet with LQR had greater body fat (g/kg of empty BW) and energy concentrations (kcal/kg of empty BW) because of a larger visceral fat deposition (P < 0.05). Using a low-quality roughage as a primary source of forage in a concentrate-based diet for growing lambs did not change NEm and the efficiency of ME use for maintenance, which averaged 71.6 kcal/kg0.75 of shrunk BW and 0.63, respectively. On the other hand, the greater nonfibrous carbohydrate content of the diet with LQR resulted in a 17% better efficiency of ME use for gain (P < 0.01), which was associated with a greater partial efficiency of energy retention as fat (P < 0.01). This increased nutritional efficiency, however, should be viewed with caution because it is related to visceral fat deposition, a nonedible tissue. [ABSTRACT FROM AUTHOR]

Corn often constitutes the main portion of high-concentrate diets fed to feedlot lambs. However, soybean hulls (SH) may be used to replace corn, and may reduce feed costs and the risk of acidosis. The objective of this experiment was to determine the effect of SH inclusion rate in high-concentrate diets on DMI, apparent digestibility of nutrients, N balance, and some rumen constituents. Sixteen ruminally fistulated Santa Inês ram lambs (44.3 ± 5 kg of BW and 6 mo old) were housed in suspended metabolism crates. A randomized complete block design experiment with 4 diets and 4 blocks was used. Blocks were defined by BW, and diets were allotted randomly within block. The control diet contained 70% corn and 0% SH. In the remaining diets, SH replaced corn at the rate of 15, 30, or 45% of the original corn concentration, which resulted in 0, 10.5, 21.0, and 31.4% of SH in the dietary DM. The DMI (kg/d) increased linearly (P < 0.01) with increasing dietary SH inclusion. A trend was observed for linear decreases (P = 0.10) in apparent DM, OM, and nonfiber carbohydrate digestibility, and a trend was observed for an increase (P = 0.08) in NDF digestibility with increasing dietary SH addition. Apparent digestibilities of CP and ether extract and ADF digestibility were not affected by SH inclusion rate. Total ruminal concentration of short-chain fatty acids was affected quadratically (P = 0.03) by diet; acetate concentration increased linearly (P < 0.01), whereas quadratic effects were observed on propionate concentration (P = 0.03) and acetate-to-propionate ratio (P < 0.01) with increasing dietary SH. Ruminal pH increased linearly (P < 0.01) as corn was replaced by SH. Nitrogen retention was not affected by the addition of SH, in spite of a linear increase in urinary N (P < 0.01). The replacement of corn grain with up to 45% SH (31.4% of SH in the dietary DM) resulted in a trend to decrease apparent digestibility of DM and to increase NDF digestibility, presenting a fermentation pattern that would reduce the risk of acidosis. [ABSTRACT FROM AUTHOR]

The objectives of this experiment were to determine the effects of replacing ground corn with soybean hulls (SH) in high-concentrate diets on the growth (56-d period), carcass characteristics, and eating behavior of feedlot lambs. Sixty-four Santa Inês ram lambs (18.3 ± 2.8 kg of BW and 69 ± 5 d of age) were assigned to a randomized complete block design experiment with 8 blocks and 4 diets. The control diet contained 10% coastcross (Cynodon sp.) hay, 70% corn, and no SH (SH0) in the dietary DM. In the remaining diets, SH replaced corn at the rate of 15 (SH15), 30 (SH30), or 45% (SH45) of the original corn concentration, resulting in 0, 10.5, 21.0, or 31.4% SH in the dietary DM. Dry matter intake increased linearly (P < 0.01) when SH replaced ground corn (1.0, 1.0, 1.1, and 1.1 kg/d for SH0, SH15, SH30, and SH45, respectively). There was no effect on ADG of lambs, with values of 276, 278, 282, and 287 g for SH0, SH15, SH30, and SH45, respectively. Feed efficiency decreased linearly (P < 0.01) with SH inclusion. Carcass measures were not affected by SH as a replacement for ground corn. Eating time, expressed as minutes per day and minutes per gram of NDF, showed a quadratic effect (P < 0.05), whereas no effect was observed when expressed as minutes per gram of DM. Rumination, in minutes per day, was not influenced by dietary SH inclusion, but a linear decrease (P < 0.01) was observed when this variable was expressed as minutes per gram of NDF. Soybean hulls can replace up to 45% of the ground corn (31.4% of SH in the dietary DM) in high-concentrate diets fed to feedlot lambs without negative effects on ADG and carcass measures. The linear decrease in feed efficiency (11.6% reduction from SH0 to SH45) suggests that optimal dietary SH inclusion rates should be dictated by the relative costs of SH and corn. [ABSTRACT FROM AUTHOR]

The high energy and protein concentration present in soybeans makes them an attractive alternative feed for feedlot lambs. Sixty-four Santa Ines ram lambs (initial BW 20 ± 0.2 kg and 75 ± 2 days old) were used to valuate the effects of using raw soybeans (RS) in high grain diets on growth efficiency, carcass characteristics and lamb cuts of feedlot lambs. A randomized complete block design, composed of eight blocks, was used. Lambs were blocked by initial weight and age and assigned to one of four treatments. Lambs were housed in 32 pens. All pens had two lambs. Pen was the experimental unit. Lambs were fed an isonitrogenous diet composed of 90% concentrate (grounded RS, soybean meal, grounded corn and minerals) and 10% coastcross hay (Cynodon spp) for 56 days. RS were added at 0, 7, 14 and 21% of the diet dry matter, corresponding to the experimental treatments RS0, RS7, RS14 and RS21, respectively. Data were analyzed using the GLM procedures of SAS. Treatment responses were determined using orthogonal polynomials (linear, quadratic or cubic). Dry matter intake and average daily gain (1.1, 1.0, 0.9 and 0.9 kg/lamb/day; 298, 275, 280 and 255 g/lamb for RS0, RS7, RS14 and RS21, respectively) decreased linearly (P<0.05) with the inclusion of raw soybeans. However, feed conversion, carcass characteristics and lamb cuts were not affected (P>0.05). Although the inclusion of RS adversely affected dry matter intake and average daily gain, even the highest level of its inclusion in the diet provided satisfactory feedlot lamb performance. [ABSTRACT FROM AUTHOR]

A high concentration of ethanol, present in sugar cane silage, may reduce voluntary feed intake affecting animal performance. Two trials were performed to evaluate the ingestive behavior of dairy goats and feedlot lambs fed diets based on fresh sugar cane or sugar cane silage. Thirty-nine Saanen goats (Trial 1) and thirty Santa Ines ram lambs (Trial 2) were assigned to a complete randomized block design. Animals were fed 50:50 (concentrate:roughage ratio) TMR rations. Roughage source was fresh chopped sugar cane (FSC), sugar cane silage without additive (SCS) or sugar cane silage treated with Lactobacillus buchneri (SCS+Lb, 5x104 cfu/g wet basis), corresponding to the experimental treatments FSC, SCS and SCS+Lb, respectively. During the feeding trial two sessions of 24 h were used to determine feeding behavior where eating and ruminating times were observed and recorded every 5 minutes. The parameters calculated were: dry matter intake (DMI, kg/day), NDF intake (kg/day), total time (min/day) and rate (min/g DM and min/g NDF) of eating, ruminating and chewing. In Trial 1, DMI was higher (P<0.01) for goats fed FSC diet (2.77 kg/d) when compared to silage diets (2.12 and 2.23 kg/d for SCS and SCS+Lb, respectively). There were no differences on eating, ruminating and chewing times. Eating and chewing rates were similar among diets. However, rumination rate (min/g DM) was higher (P<0.05) for goats fed silage diets (0.18, 0.25 and 0.25 min/g DM for FSC, SCS and SCS+Lb, respectively). In Trial 2, there was no difference on DMI among diets. Lambs spent similar time for ruminating and chewing activities. However, eating rate (min/g NDF) was lower for SCS and SCS+Lb diet when compared to FSC diet (0.43, 0.29 and 0.29 min/g DM for FSC, SCS and SCS+Lb, respectively). Sugar cane silages reduce DMI and increase rumination rate of dairy goats and decrease eating rate (min/g NDF) of feedlot lambs. [ABSTRACT FROM AUTHOR]

This trial aimed to evaluate the effects of increasing levels of raw soybeans on milk yield, composition, and fatty acid profile in ewes, and their lambs’ performance. Fifty-six Santa Ines ewes (63.9 ± 0.76 kg BW) were assigned to a randomized complete block design to receive one of the four diets containing 0 (CONT), 70, 140 or 210 g/kg DM of raw soybeans. Isonitrogenous diets (150 g/kg DM of CP) were composed of 400 g/kg DM of in natura sugarcane bagasse as roughage source and 600 g/kg DM of concentrate. The experiment lasted from 14 to 56 days of lactation. Once a week the ewes were separated from their lambs and milked mechanically. DMI (1.3, 1.3, 1.5 and 1.2 kg/day) and milk yield (1.0, 1.1, 1.1 and 1.0 kg/day) presented a quadratic effect ( P <  0.05) including 0, 70, 140 or 210 g/kg DM of raw soybeans on diets, respectively. However, milk yield corrected for fat or fat and protein, as well as content of milk fat, protein, lactose and total solids did not differ. Short (C4-C12) and medium (C14-C16) chain fatty acids decreased, whereas long-chain (C ≥ 17) fatty acids increased linearly ( P <  0.05) with raw soybeans supply. Conjugated linoleic acid (CLA; cis -9 trans -11 and trans -10 cis -12) increased ( P  ≤ 0.01) and the atherogenicity index decreased linearly ( P <  0.05) with increasing levels of raw soybeans in the diet. Unsaturated:saturated ratio, saturated, unsaturated, monounsaturated and polyunsaturated fatty acids were similar among treatments. There was no difference in lambs’ performance in pre or post-weaning periods. Considering that the price of raw soybeans is generally lower than its meal, the inclusion of up to 140 g/kg DM of soybeans is recommended for increasing milk yield, with no detrimental effect on milk efficiency production, milk components and lambs’ performance. In addition, it is important to highlight that supplementation of up to 210 g/kg DM of raw soybeans made milk fat healthier for human consumption. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the effect of wet brewers' grain (WBG) as an alternative ingredient replacing soybean meal (SBM) and ground corn (GC) on nutrient intake and apparent digestibility, ruminal fermentation characteristics, and nitrogen balance in feedlot lambs. Five ruminally cannulated ½ Dorper × ½ Santa Inês lambs, castrated with 48.3 ± 2.0 kg of initial BW and 8.3 ± 0.68-month-old (mean ± SD), were assigned in a 5 × 5 Latin square design. The experimental diets were composed of 10% roughage (Coastcross hay) and 90% concentrates, in which 85.9% of the diet was composed of GC (71.3%) plus SBM (14.6%) in the control diet. Treatments consisted in WBG inclusion levels of 7.6%, 15%, 23% and 30% replacing GC+SBM in control diet with the aim to maintain isonitrogenous concentrations. The data were analyzed using a linear or quadratic polynomial contrast in SAS. There was no effect of WBG inclusion on DMI, OM nor CP intake, but a linear increase was observed for NDF (P < 0.001), ADF (P < 0.001), EE intake (P < 0.01), and linear decrease (P < 0.001) on NFC intake. Inclusion of WBG decrease linearly NFC, while DM, OM, and CP digestibility were being lower for lambs fed a diet contained 23% WBG (quadratic component, p < 0.05). The replacement of SBM and corn grain by WBG, linearly increased the molar ratio of acetate (P < 0.01), and linearly decreased propionate (P < 0.01), resulting in a linear increase in the acetate:propionate ratio (P = 0.04). In addition, increasing the inclusion of WBG linearly increased the molar proportion of isovalerate (P < 0.05). Ruminal pH increased linearly (P < 0.001) by dietary WBG inclusion, as consequence, ruminal pH was maintained less time below 5.5 as WBG inclusion increased. Although nitrogen excretion was greater with 23% inclusion of WBG in diet (quadratic component, P < 0.05), there was no effect (P > 0.10) on retained N. Based on diet acceptability, digestibility, N retention, and ruminal fermentation parameters, it is concluded that, WBG can be used as feed ingredient up to 7.6% in diets, replacing partially SBM and GC in finishing diets for lambs. Inclusion WBG replacing SBM and partially GC, minimize the risk of acidosis in lambs fed high-concentrate diets during fattening. Inclusions beyond 23% decreased significant diet digestibility and increased ruminal acetate: propionate molar ratio, decreasing energy efficiency, increasing methane losses. • Based on diet digestibility, WBG can be used as a feed ingredient up to 7.6% in the DM of the diets. • Inclusion WBG replacing partially corn grain, minimize the risk of acidosis in lambs fed high-concentrate diets. • Inclusion WBG replacing partially, or totally, SBM did not affect N retention. • Inclusions WBG beyond 23% of the diet, increase ruminal C2:C3 molar ratio, decreasing energy efficiency. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the effects of Essential oil (EO) from Arnica montana as a feed additive on feedlot performance, ingestive behavior, carcass characteristics, rumen morphometrics characteristics and meat fatty acids profile of lambs. Forty Dorper × Santa Inês male lambs with 30.3 ± 5.76 kg (mean ± standard deviation) of initial body weight and 92 ± 9 days (mean ± standard deviation) of age were used. The experimental design was in a randomized complete block (5 treatments and 8 blocks). Lambs were fed a basal diet (160 ± 13 g/kg DM of CP; mean ± standard deviation) containing 90 % concentrate and 10 % forage (Coastcross hay). The experimental diets were: A0 - negative control (basal diet without additive); A450 - addition of 450 mg/kg DM of EO from Arnica montana ; A900 - addition of 900 mg/kg DM of EO from Arnica montana ; A1350 - addition of 1350 mg/kg DM of EO from Arnica montana ; M25 - positive control (basal diet containing 25 mg/kg DM of sodium monensin). Increasing EO from Arnica montana content conferred a quadratic effect on dry matter intake (DMI) (P = 0.02), with higher DM in A450. The DMI was higher (P < 0.01) in diets with EO from Arnica montana compared to M25. The average daily gain (ADG), body weight at slaughter (BWS), hot and cold carcass weight (HCW and CCW) increased linearly with increasing EO from Arnica montana (P < 0.05). The lambs had higher ADG, BWS, HCW and CCW with EO from Arnica montana than M25 (P < 0.05). The oocyst/g feces decreased linearly (P < 0.0001) with increasing EO from Arnica montana in the diet. However, the M25 was more efficient in reducing the oocyst than the other treatments (P < 0.05). The number of meals and time spent feeding increased linearly (P < 0.05) with the increase of EO from Arnica montana. There was a quadratic effect (P < 0.05) on feeding rate (min/g DM), with the lowest rate in A450. Time spent ruminating (min/day) was affected quadratically (P = 0.01) by increasing EO from Arnica montana , this activity was higher in A900. Compared to M25, time spent ruminating and total chewing time were longer (P < 0.05) and the feeding rate and chewing rate (min/g of NDF) were lower (P < 0.05) in diets with EO from Arnica montana. The higher inclusion of EO from Arnica montana decreased linearly the C17:0; C18:0; C18:1 trans -11, C22:6 n3 and the sum of saturated fatty acids (ΣSFA), and linearly increased the C18: 2 cis -9, cis -12; C18:3 cis -9, cis -12, cis -15, the sum of polyunsaturated (ΣPUFA) and the sum of n6 (P < 0.05). Diets with EO from Arnica montana decreased the C16:0, C17:0, C18:0 and increased the C18:2 cis -9, cis -12, ΣSFA, Σn6 and the n6/n3 ratio (P < 0.05) compared to M25. Sodium monensin at a dose of 25 mg/kg DM can be replaced by EO from Arnica montana in high-concentrate diets to promote lamb performance, carcass characteristics and fatty acid profile in the meat. The use of 1350 mg/kg DM of EO from Arnica montana was the best dose in high-concentrate diets in feedlot lambs, due to positive effect on performance, carcass characteristics, and the fatty acid profile of the meat. • Essential oil from Arnica montana is more efficient than sodium monensin in promoting performance. • The content of 1350 mg/kg DM of Essential oil from Arnica montana was most promising in improving performance. • 25 mg/kg DM of sodium monensin impaired performance, but controlled coccidiosis. • The Essential oil from Arnica montana reduces the proportion of saturated fatty acids in meat. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the effect of essential oil (EO) from Arnica montana as an additive on nutrient intake and digestibility, nitrogen balance, and rumen fermentation characteristics in feedlot lambs. Five ruminally cannulated Dorper × Santa Inês ram lambs, castrated, with 50.6 ± 1.19 kg of initial BW and 14.6 ± 1.28 month-old were distributed in a 5 × 5 Latin square design. All lambs were fed a basal diet (160.5 ± 3.06 g/kg DM of CP) containing 90 % concentrate and 10 % forage (Coastcross hay) to which the following 5 treatments were applied: 1. 0 mg/kg DM of OE from Arnica montana (A0), 2. 450 mg/kg DM of OE from Arnica montana (A450), 3. 900 mg/kg DM of OE from Arnica montana (A900), 4. 1350 mg/kg DM of OE from Arnica montana (A1350), 5. diet with 25 mg/kg DM of sodium monensin (positive control – MON). The levels of EO from Arnica montana did not alter the dry matter intake (DMI) and nutrient intake (DM, OM, CP, EE, NDF, ADF, NFC, and TDN). There was higher DM and nutrient intake for the EO from Arnica montana diets compared to MON (P < 0.05). For the comparison between MON vs. A0, there was a lower DMI and nutrients intake for MON (P < 0.05). Crude protein digestibility increased linearly (P = 0.03) in response to increasing levels of EO from Arnica montana in the diets. However, the digestibility of the other nutrients was not altered by the inclusion of EO from Arnica montana. There was no difference in nutrient digestibility for comparison between diets containing EO from Arnica montana vs. MON; and MON vs. A0. The inclusion of EO from Arnica montana in the diet linearly decreased (P = 0.03) nitrogen (N) in the urine, which was associated with a linear decrease (P = 0.03) in rumen ammonia concentration. The EO from Arnica montana contents linearly increased N retention (g/kg N intake and g/kg N absorption; P < 0.05). Diets with EO from Arnica montana had higher N intake and N excretion in urine compared to MON (P < 0.05). There was increased N retention for the diets with EO from Arnica montana when compared to MON (P = 0.02). In the contrast between MON vs. A0, there was lower N intake and lower N excretion via urine for MON (P < 0.05). The EO from Arnica montana contents conferred a quadratic effect (P = 0.03) on the molar ratio of acetate, with a lower concentration for A450. The total and individual concentrations of the other short-chain fatty acids (SCFA) were not affected by the inclusion of EO from Arnica montana. Total and individual SCFA concentrations did not differ between diets containing EO from Arnica montana vs. MON, nor between MON vs. A0. Rumen pH was not influenced by the inclusion of EO from Arnica montana in the diet, but there was a quadratic effect (P = 0.02) on the area under pH 5.5, with a greater area under 5.5 for A450. Diets with EO from Arnica montana had lower rumen pH when compared to MON (P = 0.01). The MON diet increased rumen pH compared to A0 (P < 0.01), this result contributed to a lower area under pH 5.5 and a higher total pH area for MON (P < 0.05). In conclusion, the 1350 mg/kg DM of EO from Arnica montana was the most promising, especially for the increased dietary N use efficiency, even when compared with sodium monensin. • Essential oil from Arnica montana modulates protein metabolism. • Digestibility of crude protein increased linearly with increasing essential oil from Arnica montana content in the diets. • Ruminal ammonia decreased linearly with increasing essential oil from Arnica montana content in the diets. • The increase in essential oil from Arnica montana contents in the diet linearly increases nitrogen retention. [ABSTRACT FROM AUTHOR]