Trade-offs between selection of crude protein and tannins in growing lambs.

Tannins are phenolic compounds that provide benefits to ruminants due to their protein-binding affinities and antioxidant properties. However, tannins may also have negative orosensorial and postingestive effects that decrease feed intake. This study explored how lambs trade off the ingestion of crude protein (CP) with the ingestion of potentially beneficial and toxic condensed and hydrolyzable tannins, and the ensuing impacts on diet digestibility, animal performance, and blood parameters. Thirty-two lambs were housed in individual pens for 8 wk and had access to 2 isoenergetic diets that varied in the concentration of CP (High-high in protein [HP] or Low-least preferred [LP]) and the presence of a mix of condensed and hydrolyzable tannins (4% DM). Animals were assigned to 4 treatment groups (N = 8 lambs/group) and received a simultaneous offer of: HP and LP (Control); HP and LP + tannins (HP - LP+); HP+ tannins and LP (HP + LP-); and both HP and LP with tannins (HP + LP+). All lambs preferred HP over LP and they avoided tannins in the diets (P < 0.001). Dry matter and CP intake were the lowest in HP + LP- (P < 0.0001), and DMD did not differ between Control and the other groups (P > 0.05), but it was greater for HP - LP + (P < 0.0001). CP digestibility was greater for groups without tannins in HP (P < 0.0001), but average daily gain (ADG) did not differ among treatments (P > 0.05). No differences between Control and HP + LP + were found in plasma antioxidant activity, total phenolic concentration, or haptoglobin concentration (P > 0.05). Intake of tannins was HP + LP+ > HP + LP- > HP - LP + (P < 0.0001), and fecal excretion of nitrogen (N) was HP + LP+ > HP - LP+ = HP + LP- > Control (P < 0.05). In addition, intake of tannins with both diets reduced blood urea nitrogen (BUN) concentration relative to Control (P < 0.05), thus suggesting a shift in the partitioning of N excretion from urine to feces. In summary, lambs prioritized the selection of HP over LP, regardless of the presence of a tannin extract in either or both diets. Nevertheless, lambs modulated their tannin consumption as a function of the specific diet where the tannin extract was added, with increasing levels of intake as tannins were present in just LP, then in just HP, and finally in both diets. Dietary tannins did not constrain ADG and resulted in a shift in the partitioning of N excretion from urine to feces. Such shifts have been found to result in reduced production of environmental pollutants such as ammonia, nitrous oxide, and nitrates.

Tannins are plant chemicals that can provide benefits to ruminants due to their antioxidant activity and positive effects on nutrient uptake. However, tannins could also promote negative (i.e., toxic) effects on herbivores. This study explored how lambs build their diets when offered between 2 diets that varied in protein concentration (low or high), both with and without tannins (4%) and the ensuing consequences on diet digestibility, animal performance, and some blood parameters indicative of antioxidant activity and inflammation. All lambs preferred the high-over the low-protein diet, regardless of the inclusion of tannins in the diets. Digestibility of dry matter did not differ between lambs that had diet choices with or without tannins, and body weight gains were not different across all treatments. No differences were found among dietary treatment groups in blood antioxidant activity or indicators of inflammation. Tannin intake promoted a shift in the fate of nitrogen excretion from urine to feces, suggesting reductions in environmental pollutants such as ammonia, nitrous oxide, and nitrates. Thus, tannins did not promote negative impacts on animal performance with potential concomitant beneficial effects on the environment.

Preliminary Report on Diet Estimation of Taruka (Hippocamelus antisensis d'Orbigny, 1834) in an Agricultural Area of the Andean Foothills of the Tarapacá Region, Chile.

The success of conservation programs for the taruka (Hippocamelus antisensis d'Orbigny), an endemic and endangered deer, depends on many factors, highlighting anthropogenic and ecological effects. Among the latter, how this herbivore interacts with forage resources is important. The objective of the study was to describe the main attributes of the diet of this deer in rangelands adjacent to agricultural areas of the foothills of the Tarapacá Region, Chile. The botanical composition of the diet (BCD) was determined by microhistology of feces and fecal nitrogen (NF, %) was measured in two contrasting seasons (rainy summer and dry winter). From the BCD and FN, their relative diversity (J) and crude protein percentage were estimated. In the BCD, Medicago sativa dominated (27.6 ± 8.2% vs. 53.9 ± 9.2%, in rainy summer and dry end winter, respectively), followed by herbaceous dicots (46.2 ± 9.4% vs. 19.4 ± 8.7%) and shrubby species (21.5 ± 7.8% vs. 23.4 ± 7.0%), from rangelands. The contribution of grasses and graminoid species was low, not exceeding 3% and 0.4% of the diet, respectively, with no differences between seasons of the year. Intake of horticultural crop species was marginal (1.3 ± 1.3%), being detected only in the wet season. Diet relative diversity was higher during the wet period (0.75 ± 0.07) compared to the dry period (0.58 ± 0.06), since in the first period it was possible to find a greater number of palatable species. There were no significant differences in the FN attributed to the time of the year (average of 1.8 ± 0.19%), which indicates that the diet of this deer would be stable in terms of its protein quality. These FN levels estimate sufficient dietary protein content to satisfy maintenance and early pregnancy, but these could be limiting during late gestation and lactation.

Botanical Composition and Diet Quality of the Vicuñas (Vicugna vicugna Mol.) in Highland Range of Parinacota, Chile.

Understanding the botanical composition of herbivores' diets and their nutritional quality is an important question in the development of sustainable strategies for the management of natural resources. In Chilean highland vicuña-grazed grasslands, there is little information in this regard and, therefore, this study aimed to determine the year-round profile of the diet's botanical composition and quality. In highland grasslands, on an area of 21.9 ha, continuously grazed for 3.06 VU/ha/year (18°03' S, 69°13' W; 4425 m.o.s.l), twelve feces piles were sampled monthly and were analyzed through microhistology, and the nitrogen concentration [NF, OM basis] was determined. The botanical composition, diversity (J) and selectivity index (Ei) of the main species were estimated. Diets were composed of dry-grassland grasses (37.7%), wet-grassland grasses (36.6%), graminoids (14.3%) and forbs (10.2%). The diet diversity ranged from 0.79 (dry-winter) to 0.87 (wet-summer). The main dominant grassland species obtained negative Ei values. The annual mean value of [NF] was estimated as 1.82%, with a higher value in summer months (2.21%), which coincides with the physiological states of higher nutritional demand. The vicuñas behave like generalist ungulates, having a high degree of selectivity towards grass species, which mostly fulfill a nutritional role in subsistence and a functional role in survival, applying foraging strategies that allow them to obtain a better quality diet during the season of greatest nutritional demand.

Fibrous feedstuffs for the nitrogen retention of growing pigs / Contribuição dos alimentos fibrosos para a retenção de nitrogênio de suínos em crescimento

The aim of this study was to measure the nitrogen (N) balance of pigs fed with lysine-limiting diets containing practical levels of wheat bran (WB) or soybean hulls (SH). Twelve pigs with average weights of 57.36±2.01 and 72.68±3.24 kg were used in trials 1 and 2, respectively. In trial 1, treatments were CT1 - control diet and WB - diet with inclusion of 15% WB. In trial 2, CT2 - control diet and SH - diet with inclusion of 6% SH. Fibrous diets increased (P<0.05) the fecal N in 63.54 and 60.55% in relation to CT1 and CT2, respectively. The urinary N was higher (P<0.05) in pigs receiving the WB diet, but was not influenced in the trial with SH. The N retention (NRET) was higher (P>0.05) in pigs ingesting the WB diet; although, when the proportion of NRET was expressed relative to N ingested (NING) there was no difference (P>0.05) between treatments. Inclusion of SH did not affect (P>0.05) the NRET when the result was expressed in absolute or proportional terms. In conclusion, inclusion of practical levels of WB and SH does not significantly affect the metabolic costs involved with nitrogen metabolism. However, only WB was able to contribute to the N balance of pigs, while the relative amount of N added by SH was fully recovered in feces.(AU)

O objetivo deste estudo foi medir o balanço de nitrogênio (N) de suínos alimentados com dietas limitantes em lisina contendo níveis práticos de inclusão de farelo de trigo (FT) ou casca de soja (CS). Foram utilizados 24 suínos machos castrados com peso médio inicial de 57,36±2,01 kg e 72,68±3,24 kg nos experimentos 1 e 2, respectivamente. No experimento 1 os tratamentos foram CT1 - dieta controle, e FT - dieta com inclusão de 15% de FT. No experimento 2 CT2 - dieta controle, e CS - dieta com inclusão de 6% CS. As dietas fibrosas aumentaram (P<0,05) o N fecal em 64,54 e 60,55% em relação a CT1 e CT2, respectivamente. O N urinário foi maior (P<0,05) nos suínos que receberam a dieta FT, mas não foi afetado no experimento com CS. A retenção de N (NRET) foi maior (P<0,05) nos suínos alimentados com a dieta FT, entretanto quando a proporção do NRET foi expressa em relação ao N ingerido (NING) não houve diferença entre os tratamentos (P<0,05). A inclusão de CS não afetou (P<0,05) a NRET quando os resultados foram expressos em termos absolutos ou proporcionais. Em conclusão, a inclusão de níveis práticos de FT ou CS não afeta significativamente o custo metabólico envolvido no metabolismo de N. Entretanto, apenas o FT foi capaz de contribuir para o balanço de N dos suínos, enquanto a quantidade N relativa a adição de CS foi totalmente recuperada nas fezes.(AU)

Fibrous feedstuffs for the nitrogen retention of growing pigs / Contribuição dos alimentos fibrosos para a retenção de nitrogênio de suínos em crescimento

ABSTRACT: The aim of this study was to measure the nitrogen (N) balance of pigs fed with lysine-limiting diets containing practical levels of wheat bran (WB) or soybean hulls (SH). Twelve pigs with average weights of 57.36±2.01 and 72.68±3.24 kg were used in trials 1 and 2, respectively. In trial 1, treatments were CT1 - control diet and WB - diet with inclusion of 15% WB. In trial 2, CT2 - control diet and SH - diet with inclusion of 6% SH. Fibrous diets increased (P<0.05) the fecal N in 63.54 and 60.55% in relation to CT1 and CT2, respectively. The urinary N was higher (P<0.05) in pigs receiving the WB diet, but was not influenced in the trial with SH. The N retention (NRET) was higher (P>0.05) in pigs ingesting the WB diet; although, when the proportion of NRET was expressed relative to N ingested (NING) there was no difference (P>0.05) between treatments. Inclusion of SH did not affect (P>0.05) the NRET when the result was expressed in absolute or proportional terms. In conclusion, inclusion of practical levels of WB and SH does not significantly affect the metabolic costs involved with nitrogen metabolism. However, only WB was able to contribute to the N balance of pigs, while the relative amount of N added by SH was fully recovered in feces.

RESUMO: O objetivo deste estudo foi medir o balanço de nitrogênio (N) de suínos alimentados com dietas limitantes em lisina contendo níveis práticos de inclusão de farelo de trigo (FT) ou casca de soja (CS). Foram utilizados 24 suínos machos castrados com peso médio inicial de 57,36±2,01 kg e 72,68±3,24 kg nos experimentos 1 e 2, respectivamente. No experimento 1 os tratamentos foram CT1 - dieta controle, e FT - dieta com inclusão de 15% de FT. No experimento 2 CT2 - dieta controle, e CS - dieta com inclusão de 6% CS. As dietas fibrosas aumentaram (P<0,05) o N fecal em 64,54 e 60,55% em relação a CT1 e CT2, respectivamente. O N urinário foi maior (P<0,05) nos suínos que receberam a dieta FT, mas não foi afetado no experimento com CS. A retenção de N (NRET) foi maior (P<0,05) nos suínos alimentados com a dieta FT, entretanto quando a proporção do NRET foi expressa em relação ao N ingerido (NING) não houve diferença entre os tratamentos (P<0,05). A inclusão de CS não afetou (P<0,05) a NRET quando os resultados foram expressos em termos absolutos ou proporcionais. Em conclusão, a inclusão de níveis práticos de FT ou CS não afeta significativamente o custo metabólico envolvido no metabolismo de N. Entretanto, apenas o FT foi capaz de contribuir para o balanço de N dos suínos, enquanto a quantidade N relativa a adição de CS foi totalmente recuperada nas fezes.

Protein requirements of collared peccary (Pecari tajacu).

A nitrogen (N) balance digestion trial was conducted to determine the protein requirement of collared peccaries (Pecari tajacu). In a 4 × 4 Latin square design, four captive adult male peccaries were fed four isoenergy diets containing four different levels of N (11.7, 16.3, 22.8, and 26.7 g N/kg of dry matter-DM). After 15 days of adaptation, a total collection of feces and urine was carried out for five consecutive days. Regression analyses between N intake and N in feces and urine allowed to calculate the metabolic fecal nitrogen (MFN = 2.3 g N/kg of dry matter intake-DMI) and daily endogenous urinary N (EUN = 185 mg N/kg0.75). Likewise, by regression analyses between consumption of nitrogen and the nitrogen balance (NB = N ingested - N excreted, mg N/kg0.75), a daily requirement of 514 mg N/kg0.75 was calculated. Therefore, if food intake is unrestricted, collared peccaries require a minimum in their diet of about 5.4% crude protein on DM basis. These values are almost as low as those found for browsing and frugivorous wild ruminants, which reinforce the proposition that peccaries' digestive physiology is nearer to that of domestic and wild ruminants than domestic pigs. This relatively low protein requirement of collared peccary and its great ability to digest protein reveal the relevance of the forestomach for the species on nitrogen/protein metabolism and allow the use of diets with lower crude protein levels than the commercial ones used for the domestic pig, which reduces feed costs.

Methods to determine forage intake by lambs on Italian ryegrass / Métodos para determinação do consumo de forragem por cordeiras em pastagem de azevém

This study was conducted to evaluate the use of chromium oxide and the content of fecal nitrogen to estimate forage intake by female lambs on Italian ryegrass pasture. The pasture was managed under different forage allowances (FA): 6, 9 and 12% BW. The experiment was a randomized split-split plot design, in which the forage allowances were considered as main plots, the phenological stages as subplots and methods to determine intake as sub-subplots. Forage intake, in the ryegrass vegetative stage, is independent of forage allowance. Lower allowances limit forage intake from the pre-flowering stage, while at the reproductive stage, intake was lower in FA6, intermediate in FA9 and higher in FA12. The estimation of organic matter intake by lambs on Italian ryegrass is similar when chromium oxide and fecal nitrogen are used as markers. The forage intake according to forage allowances depends on the sward structure and is limited by high stem mass at the end of the phenological cycle.(AU)

Este experimento foi realizado para mensurar a ingestão de forragem por cordeiras, em pastagem de azevém, utilizando o óxido de cromo e o teor de nitrogênio fecal. A pastagem foi manejada sob distintas ofertas de forragem (OF): 6, 9 e 12% do PC. O delineamento experimental foi inteiramente casualizado, com estrutura de parcelas sub subdivididas, sendo as ofertas de forragem as parcelas principais, os estádios fenológicos, as subparcelas e os métodos de determinação da ingestão as sub sub-parcelas. A ingestão nos estádios vegetativo do azevém independe da oferta de forragem. As menores ofertas limitam a ingestão de forragem a partir do pré-florescimento enquanto no estádio reprodutivo do azevém a ingestão é menor na OF6, intermediária na OF9 e maior OF12. A estimativa da ingestão de matéria orgânica por cordeiras em pastagem de azevém é similar quando são utilizados o óxido de cromo e o nitrogênio fecal como marcadores. A ingestão de forragem em função das ofertas de forragem é dependente da estrutura do dossel e é limitada no final do ciclo do pasto em função da elevada massa de colmos <(>AU)ipt

Methods to determine forage intake by lambs on Italian ryegrass / Métodos para determinação do consumo de forragem por cordeiras em pastagem de azevém

This study was conducted to evaluate the use of chromium oxide and the content of fecal nitrogen to estimate forage intake by female lambs on Italian ryegrass pasture. The pasture was managed under different forage allowances (FA): 6, 9 and 12% BW. The experiment was a randomized split-split plot design, in which the forage allowances were considered as main plots, the phenological stages as subplots and methods to determine intake as sub-subplots. Forage intake, in the ryegrass vegetative stage, is independent of forage allowance. Lower allowances limit forage intake from the pre-flowering stage, while at the reproductive stage, intake was lower in FA6, intermediate in FA9 and higher in FA12. The estimation of organic matter intake by lambs on Italian ryegrass is similar when chromium oxide and fecal nitrogen are used as markers. The forage intake according to forage allowances depends on the sward structure and is limited by high stem mass at the end of the phenological cycle.

Este experimento foi realizado para mensurar a ingestão de forragem por cordeiras, em pastagem de azevém, utilizando o óxido de cromo e o teor de nitrogênio fecal. A pastagem foi manejada sob distintas ofertas de forragem (OF): 6, 9 e 12% do PC. O delineamento experimental foi inteiramente casualizado, com estrutura de parcelas sub subdivididas, sendo as ofertas de forragem as parcelas principais, os estádios fenológicos, as subparcelas e os métodos de determinação da ingestão as sub sub-parcelas. A ingestão nos estádios vegetativo do azevém independe da oferta de forragem. As menores ofertas limitam a ingestão de forragem a partir do pré-florescimento enquanto no estádio reprodutivo do azevém a ingestão é menor na OF6, intermediária na OF9 e maior OF12. A estimativa da ingestão de matéria orgânica por cordeiras em pastagem de azevém é similar quando são utilizados o óxido de cromo e o nitrogênio fecal como marcadores. A ingestão de forragem em função das ofertas de forragem é dependente da estrutura do dossel e é limitada no final do ciclo do pasto em função da elevada massa de colmos

Nitrogen requirements of white-lipped peccary (Mammalia, Tayassuidae).

A study was conducted to determine the protein requirement of the white-lipped peccary (Tayassu pecari) performing a nitrogen (N) balance digestion trial. In a 4 × 4 Latin square design, four adult captive male peccaries were fed four isoenergetic diets containing four different levels of N (13.3, 19.2, 28.7, and 37.1 g N/kg dry matter). After 15 days of adaptation, the total collection of feces and urine was carried out for five consecutive days. By regression analysis between N intake and N in feces and urine, the metabolic fecal nitrogen (MFN = 3.1 g/kg of dry matter intake) and daily endogenous urinary N (EUN = 91.0 mg/kg(0.75) ) were determined. Likewise, by regression analyses between consumption of nitrogen and the nitrogen balance [NBN consumed-(fecal N + Urine N)] we estimated the daily requirement of 336.5 mgN/kg(0.75) . Therefore, if food intake is unrestricted, white-lipped peccaries require a minimum content in their diet of about 4.5% crude protein as percentage of dry diet. These values are similar to those found in frugivorous wild ruminants, which reinforces the proposition that peccaries have a digestive physiology nearer to that of ruminants than of domestic pigs. Furthermore, the low nutritional maintenance requirements for white-lipped peccary may explain how this species thrive in the Neo-tropical region eating predominantly palm-fruits that normally have low crude protein contents.