Function,size and form of the gastrointestinal tract of the collared <Emphasis Type="Italic">Pecari tajacu</Emphasis> (Linnaeus 1758) and white-lipped peccary <Emphasis Type="Italic">Tayassu pecari</Emphasis> (Link 1795)

The peccary digestive tract is characterised by an elaborate forestomach. In order to further characterise the digestive function of peccaries, we report body mass, digestive organ mass, content mass of the gastrointestinal tract compartments and their length and width, as well as liver, parotis and mandibular gland mass. Our data on eleven collared and four white-lipped peccaries suggest that peccaries have a small relative stomach volume compared to other foregut fermenters, which implies a comparatively lower fermentative capacity and thus forage digestibility. The forestomach could enable peccaries to deal, in conjunction with their large parotis glands, with certain plant toxins (e.g. oxalic acid). The finding of sand being trapped in the forestomach blindsacs could indicate a disadvantage of the peccary forestomach design. The relevance of the forestomach to peccaries remains enigmatic.     

Diet Overlap and Foraging Activity between Feral Pigs and Native Peccaries in the Pantanal

Inter-specific competition is considered one of the main selective pressures affecting species distribution and coexistence. Different species vary in the way they forage in order to minimize encounters with their competitors and with their predators. However, it is still poorly known whether and how native species change their foraging behavior in the presence of exotic species, particularly in South America. Here we compare diet overlap of fruits and foraging activity period of two sympatric native ungulates (the white-lipped peccary, Tayassu pecari, and the collared peccary, Pecari tajacu) with the invasive feral pig (Sus scrofa) in the Brazilian Pantanal. We found high diet overlap between white-lipped peccaries and feral pigs, but low overlap between collared peccaries and feral pigs. Furthermore, we found that feral pigs may influence the foraging period of both native peccaries, but in different ways. In the absence of feral pigs, collared peccary activity peaks in the early evening, possibly allowing them to avoid white-lipped peccary activity peaks, which occur in the morning. In the presence of feral pigs, collared peccaries forage mostly in early morning, while white-lipped peccaries forage throughout the day. Our results indicate that collared peccaries may avoid foraging at the same time as white-lipped peccaries. However, they forage during the same periods as feral pigs, with whom they have lower diet overlap. Our study highlights how an exotic species may alter interactions between native species by interfering in their foraging periods.     

The defensive behavioral patterns of captive white-lipped and collared peccary (Mammalia,Tayassuidae): an approach for conservation of the species

Defensive behavioral patterns in response to human-induced rapid environmental change can affect animals’ fitness and may play a role in species conservation status. To test this hypothesis, we compared the risk assessment and defensive behavioral responses of captive white-lipped peccary (WLP; Tayassu pecari) and collared peccary (CP; Pecari tajacu), which retain different conservation status; WLP are considered vulnerable and CP of least concern. We used an adapted paradigm of the mouse defense test battery (MDTB) comprising four consecutive tests. Two of these tests simulated a novel environment, while the other two stimulated the expression of defensive behavioral patterns. Besides differences in risk assessment and defensive threat/attack behavioral patterns between species, we compared flight initiation distance, flight speed, and plasma glucocorticoid concentrations. When facing a novel environment and risk challenges from humans’ predator-like cues, the white-lipped peccary showed more exploratory and defensive threat/attack behavioral patterns, shorter flight initiation distances, and lower flight speeds, whereas the collared peccaries showed more cautious and retreat patterns, longer flight initiation distances, and higher flight speeds. There were also correlations between physiological and behavioral parameters. We confirmed our hypothesis that the collared peccary’s cautiousness may help to prevent a decrease in its population, while the white-lipped peccary’s exploratory and confrontational behavioral patterns in overhunted areas, together with other simultaneous factors as forest fragmentation, might contribute to placing this species in the vulnerable category.     

Collared peccary (Pecari tajacu) behavioral reactions toward a dead member of the herd

Humans, elephants, chimpanzees, and cetaceans show concern with the death of other members of their species and respond to death in particular ways. Science considers that these species are exceptions and that other mammal species show little or no reaction to the dead bodies of individuals of their species. Collared peccaries (Pecari tajacu; Tayassuidae) are social animals that live in groups of 5–50 individuals maintaining close and complex social relationships. The collared peccary occupies many different environments and it is widely distributed from the south of North America to the north of Argentina. Their behavior is well studied, but we know little about their behavior toward the dead. We directly observed and filmed with a camera trap the reactions of a five‐member herd of collared peccaries to the death of a herd member. We worked on a suburban forested area in the mountains of central Arizona. We found that the herd visited and spent time with the dead body for 10 days after the peccary died. The frequency of the visits declined until the cadaver was consumed by coyotes. Most of the videos showed two individuals visited the dead animal (44%), solitary records were also frequent (39%) and only 4% of the videos recorded three peccaries. Visits were more frequent during the night (64%). Peccaries do react to the death of a herd member by behaving in particular ways. Reactions include pushing at the dead individual, staring at it, biting it, and trying to pick it up by putting their snout under the corpse and pushing it up, and defending it from coyotes, among others. These levels of behavioral complexity for peccaries are beyond those known so far. The behaviors of this herd of peccaries resemble those of humans, cetaceans, chimpanzees, and elephants and show that these groups are not the only ones that react to death.     

Interspecific association between an ungulate and a carnivore or a primate

In the Brazilian Pantanal, we observed collared peccaries (Pecari tajacu) associating with South American coatis (Nasua nasua) 13 times and three times with black howler monkeys (Alouatta caraya). The scansorial coati drop fruit whilst feeding that both collared peccaries and other coatis consume. Young coatis were also observed chewing on the pulp left over from seeds spat out by collared peccaries who had removed the hard exocarp. Both species react to each other’s alarm calls. Peccaries also benefited from the fruits dropped by black howler monkeys. Ecologically, coatis are omnivores; but taxonomically, they are carnivores. To our knowledge, the collared peccary/coati association is the first report of an interspecific association between an ungulate and a carnivore.     

Do Collared Peccaries Negatively Impact Understory Insectivorous Rain Forest Birds Indirectly Via Lianas and Vines?

Tropical rain forest understory insectivorous birds are declining, even in large forest reserves, yet the mechanisms remain unclear. Abundant large mammals can reshape forest structure, which degrades foraging microhabitat. We used six sites in Nicaragua, Costa Rica, and Panama with varying collared peccary (Pecari tajacu) density to test three linked hypotheses: (1) locally declining understory insectivores forage preferentially in liana tangles; (2) vine and liana density, cover, and frequency of dense tangles are lower in the presence of abundant collared peccaries; and consequently (3) abundant collared peccaries are associated with reduced understory insectivorous bird abundance. Three insectivores that declined at La Selva preferentially foraged in liana tangles: Checker‐throated Antwren (Epinecrophylla fulviventris), Dot‐winged Antwren (Microrhopias quixensis), and Ruddy‐tailed Flycatcher (Terenotriccus erythrurus). Vine density, liana cover, liana tangle frequency, and forest cover were lower in the presence of collared peccaries relative to experimental mammal exclosures, with the greatest differences at La Selva Biological Station, Costa Rica. Across sites, five of seven vine and liana measures showed negative, curvilinear relationships with peccary densities. Vine and liana measures peaked at sites with intermediate peccary density, and were low at La Selva. Structural equation models suggest negative indirect effects of the collared peccaries on focal bird densities, mediated by vine and liana density, cover, or tangle frequency. Forest area and rainfall affected both lianas and birds, but collared peccaries also contributed to the reduced abundance of understory insectivores. Indirect effects such as that suggested here may occur even in large, protected forest reserves where large mammal communities are changing.     

Impact of barley form on equine total tract fibre digestibility and colonic microbiota

This study aimed at assessing the impact of four barley forms on total tract apparent digestibility of dietary fibre in horses fed a large amount of starch in the morning meal (0.27% BW). Processed barley forms had a greater pre-caecal starch digestibility than the whole form. Based on this result, we hypothesised that using barley-processing methods would limit the potential dumping of undegraded starch in the hindgut of horses and, consequently, the potential negative effect on fibre degradation in the hindgut. In a 4×4 latin square design, four mature geldings fitted with a right ventral colon-fistula were fed a meadow hay : concentrate (62 : 38; dry matter (DM) basis) diet at 1.7% BW. The concentrate was made of 80% barley distributed either as whole grain or as processed forms: 2.5 mm ground, pelleted or steam-flaked. For each period, total tract apparent digestibilities of DM, NDF and ADF were determined over 3 consecutive days by total faecal collection, whereas pH, volatile fatty acids (VFA) concentrations and cultural functional bacteria counts (total anaerobic, cellulolytic bacteria, lactic acid producers, amylolytic bacteria and lactic acid utilisers) in colonic content were evaluated on 1 day 4 h after the morning meal. Total tract apparent digestibility of DM and dietary fibre was influenced (P<0.05) by barley form. Diets including thermo-mechanically treated barley forms led to a higher (P<0.05) total tract apparent digestibility of NDF than those constituted of ground barley and also led to a greater (P<0.05) total tract apparent digestibility of ADF than those made of whole or ground barley forms. However, no significant difference was observed in colonic pH, VFA concentrations and cultural bacteria concentrations. Owing to a high starch supply in the morning meal, the concentration of the functional bacteria in the colonic content averaged 7.8 log CFU/ml, 5.9 NPM/ml, 6.9 and 7.3 CFU/ml for total anaerobic, cellulolytic, amylolytic and lactic acid-utilising bacteria, respectively. Consequently, providing horses with pelleted or steam-flaked instead of ground barley forms may limit the negative impact of starch on fibre digestibility in horses fed a high level of starch in the morning meal (0.27% BW). Moreover, the fibre-to-starch ratio fed in this experiment did not cause any digestive upset.     

Effect of centrifugation and sugar supplementation on the semen cryopreservation of captive collared peccaries (Tayassu tajacu)

The present study is aimed at evaluating the effect of centrifugation for seminal plasma removal and the supplementation of fructose or glucose to the Tris-based extender on the kinematic patterns of the motility parameters of frozen–thawed semen obtained from captive collared peccaries (Tayassu tajacu). Semen samples (n = 14) were collected from 10 sexually mature male collared peccaries by electroejaculation. These samples were further evaluated for parameters such as motility, vigor, sperm viability, membrane integrity, and sperm morphology. The samples were divided into four aliquots, and only two of these aliquots were centrifuged. The semen aliquots (centrifuged and raw semen samples) were diluted in Tris-based extenders supplemented with fructose or glucose. Egg yolk (20%) and glycerol (3%) were added to all the samples which were cryopreserved in liquid nitrogen and thawed at 37 °C/1 min. The frozen–thawed semen was evaluated for the same parameters described for the fresh semen. On the other hand, the kinematic motility patterns were evaluated by a computer-aided system. After thawing, it was observed that the values for the total sperm motility were around 30% for all the samples. A negative effect of centrifugation was verified for parameters such as sperm morphology, linearity, straightness, and beat cross frequency (P < 0.05). However, no differences between fructose and glucose were verified for any semen end point (P > 0.05). In conclusion, it is not recommended to centrifuge the ejaculates from collared peccaries prior to conducting the cryopreservative procedures using a Tris-based extender supplemented with fructose or glucose.     

Effect of centrifugation and sugar supplementation on the semen cryopreservation of captive collared peccaries (Tayassu tajacu)

The present study is aimed at evaluating the effect of centrifugation for seminal plasma removal and the supplementation of fructose or glucose to the Tris-based extender on the kinematic patterns of the motility parameters of frozen–thawed semen obtained from captive collared peccaries (Tayassu tajacu). Semen samples (n = 14) were collected from 10 sexually mature male collared peccaries by electroejaculation. These samples were further evaluated for parameters such as motility, vigor, sperm viability, membrane integrity, and sperm morphology. The samples were divided into four aliquots, and only two of these aliquots were centrifuged. The semen aliquots (centrifuged and raw semen samples) were diluted in Tris-based extenders supplemented with fructose or glucose. Egg yolk (20%) and glycerol (3%) were added to all the samples which were cryopreserved in liquid nitrogen and thawed at 37 °C/1 min. The frozen–thawed semen was evaluated for the same parameters described for the fresh semen. On the other hand, the kinematic motility patterns were evaluated by a computer-aided system. After thawing, it was observed that the values for the total sperm motility were around 30% for all the samples. A negative effect of centrifugation was verified for parameters such as sperm morphology, linearity, straightness, and beat cross frequency (P < 0.05). However, no differences between fructose and glucose were verified for any semen end point (P > 0.05). In conclusion, it is not recommended to centrifuge the ejaculates from collared peccaries prior to conducting the cryopreservative procedures using a Tris-based extender supplemented with fructose or glucose.     

Evaluation of genetic variability in the collared peccary Pecari tajacu and the white-lipped peccary Tayassu pecari by microsatellite markers

In this study, the microsatellite technique was used to evaluate the genetic variability in populations of collared and white-lipped peccaries kept in captivity. Six primers developed for domestic pigs were used and amplified in both species. They revealed the presence of five polymorphic loci and one monomorphic locus. The polymorphic loci included 4 of the 16 alleles in collared peccaries, and 3 of the 10 alleles in the white-lipped peccaries. Polymorphic information content (PIC) in both species and all the loci was highly informative. The probability of paternity exclusion (PEC), if one of the parents is known, was almost as high in white-lipped peccaries (95.53%) as in the collared (99,48%). The Fst values for collared (0.042) and white-lipped (0.1387) peccaries showed that both populations are not structured. The Fis values for all loci, except ACTG2 in white-lipped peccaries (-0.0275) and in both species (0.1985 to 0.9284 in collared peccaries and 0.3621 to 0.4754 in the white-lipped), revealed a high level of homozygosis, probably caused by inbreeding. Data on heterologous amplification and genetic variability in collared and white-lipped peccaries are presented for the first time.     

Intraspecific aggression results in death of a collared peccary

An adult male collared peccary (Dicotyles tajacu) caught from the wild was released into an outdoor enclosure containing 12 other wild adult peccaries. The introduced male died of severe infection as a result of scrotal wounds inflicted by resident peccaries.     

Supplementing high-quality fresh forage to growing lambs fed a total mixed ration diet led to higher intake without altering nutrient utilization

The effect of supplementing high-quality fresh forage, mainly based on alfalfa, to growing lambs fed with decreasing levels of total mixed ration (TMR) was studied on intake, digestion and ruminal environment. In total, 24 catheterized lambs (25.2±3.67 kg) housed in individual metabolism cages were assigned to one of four treatment diets: ‘TMR100’: TMR offered ad libitum; ‘TMR75’ and ‘TMR50’: TMR at a level of 0.75 and 0.50 of potential intake, respectively, complemented with fresh forage without restriction; ‘TMR0’: only fresh forage ad libitum. The feeding behavior, nutrient intake and digestibility, kinetics of passage and rumen environment were evaluated. As the level of TMR in the diet decreased, lambs increased the forage intake and spent more time eating and ruminating, less time resting and demonstrated a higher rate of intake. Those changes resulted in a higher nutrient intake of dry matter, organic matter, nitrogen, NDF and ADF, but a slightly lower organic matter digestibility, while no differences were detected in the output rate of particles. As a consequence, with the decrease of TMR and increase of forage intake, the ingested energy increased. Higher ruminal pH and NH₃–N concentrations were observed for lower levels of TMR in the diet. The total volatile fatty acids, acetate and propionate concentrations presented a quadratic response. Total volatile fatty acids and acetate concentrations were higher and propionate concentration was lower in lambs consuming mixed diets (TMR50 and TMR75). We concluded that the inclusion of high-quality fresh forage in a combined diet with TMR in lambs had positive effects on nutrient intake without negative consequences on digestion and rumen environment.     

Digestibility of a high-fiber biscuit-based diet by black and white colobus (Colobus guereza)

The acceptability and digestibility of a high-fiber biscuit-based diet was investigated using two adult male Colobus guereza animals. Although the animals were initially reluctant to accept the biscuit, it was eventually readily consumed. Apparent digestion coefficients for the diet (average composition, dry matter basis: 16% crude protein, 25% neutral detergent fiber (NDF), 9.5% acid detergent fiber (ADF), 1.2% acid lignin) determined by total fecal collection were 0.871 for dry matter, 0.813 for NDF, 0.693 for ADF, and 0.208 for acid lignin. Fiber digestive capabilities in C. guereza generally exceeded those reported in ruminant species based on predictive equations. Use of acid lignin and Cr₂O₃ as markers underestimated dry matter digestibility by 3.9 and 6.0%, respectively.     

Influence of the thawing rate on the cryopreservation of semen from collared peccaries (Tayassu tajacu) using Tris-based extenders

The objective was to evaluate the influence of the thawing rate on the quality of frozen-thawed (cryopreserved in Tris-based extenders) semen obtained from collared peccaries (Tayassu tajacu). Semen from 13 sexually mature collared peccaries males were collected by electroejaculation, and evaluated for motility, vigor, sperm viability, membrane integrity, and sperm morphology. Semen was divided in two equal portions: the first was diluted in Tris-fructose and the other in Tris-glucose, with egg yolk (20%) and glycerol (3%) added to each portion. Extended semen was frozen in liquid nitrogen and thawed using two thawing protocols (37 °C for 1 min or 55 °C for 7 s, followed by an additional 30 s at 37 °C). There were no significant differences between the two extenders after extension, chilling, or glycerol addition. After thawing at 37 °C, there were 37.9 ± 4.2% and 28.5 ± 5.1% motile spermatozoa for samples extended in Tris-fructose and Tris-glucose, respectively, with 33.8 ± 3.7% and 28.2 ± 3.5% motile spermatozoa after thawing at 55 °C (no significant differences). Furthermore, there were no significant interactions between extenders and thawing protocols for any semen end point. In conclusion, semen from collared peccaries was successfully cryopreserved in Tris-based extenders and thawed with two protocols (37 °C for 1 min or 55 °C for 7 s).     

Digestibility of diets containing increasing levels of NaOH-treated or untreated wheat straw

Sodium hydroxide-treated or untreated wheat straw was included in a basal alfalfamaize diet at 0, 10, 20 and 40%. As the level of straw increased, the apparent digestibility of dry matter (DM) and organic matter (OM) by sheep, decreased linearly (P < 0.01), with a faster decrease (P < 0.05) for diets containing untreated straw. The digestibility of DM decreased by 0.22 and 0.41% and OM by 0.24 and 0.42% for treated and untreated straw diets, respectively, with each 1% increase of straw in the diets.Addition of treated straw increased (P < 0.05) digestibility of cell wall constituents (CWC), acid detergent fibre (ADF) and hemicellulose (HC). However, when untreated straw was added, the digestibility of HC was reduced, whereas the digestibility of CWC and ADF was dependent on the level of straw added. Increasing levels of NaOH-treated straw in the diets produced linear increases (P < 0.05) in digestibility of CWC, ADF and HC. However, significant (P < 0.05) linear or quadratic responses were not noted in the digestibility of CWC, ADF and HC with increasing levels of untreated straw in the diet. Apparent digestibility of crude protein was not affected by addition of either NaOH-treated or untreated straw to the diet.In general, although changes in nutrient digestibility of the basal component small, large changes in the digestibility of nutrients in the straw component were apparent and accounted for the major differences in digestibility of the diets. The absence of curvilinearity in the regression equations suggested that there were no associative effects.     

Effects of konjac flour inclusion in gestation diets on the nutrient digestibility,lactation feed intake and reproductive performance of sows

This study was conducted to investigate the effects of konjac flour (KF) inclusion in gestation diets of sows on nutrients digestibility, lactation feed intake, reproductive performance of sows and preweaning performance of piglets. Two isoenergetic and isonitrogenous gestation diets were formulated: a control diet and a 2.1% KF-supplemented diet (KF diet). Both diets had the same NDF and insoluble fiber (ISF) levels, but the KF diet had higher soluble fiber (SF) level. The day after breeding, 96 multiparous sows were assigned to the two dietary treatments. Restrict-fed during gestation, in contrast, all sows were offered the same lactation diet ad libitum. Response criteria included sow BW, backfat depth, lactation feed intake, weaning-to-estrus interval, litter size and piglet’s weight at parturition and day 21 of lactation. On day 60 of gestation, 20 sows were used to measure nutrient digestibility. Results showed that the digestibility of dry matter, gross energy, crude fiber and ADF were not affected by the dietary treatments. The inclusion of KF in gestation diets increased NDF digestibility (P<0.05) and tended to increase the digestibility of CP (P=0.05) compared with the control diet group. In addition, dietary treatment during gestation did not affect litter size, BW and backfat gain during gestation, lactation weight, backfat loss or weaning-to-estrus interval of sows. However, sows fed the KF diet consumed more (P<0.05) lactation diet per day than sows in the control group. Accordingly, sows fed the KF diet showed greater average piglet weights on day 21 of lactation (P=0.09), and the litter weight of sows fed the KF diet on day 21 of lactation increased by 3.95 kg compared with sows fed the control diet (not significant). In conclusion, the inclusion of KF in gestation diets increased lactation feed intake of sows and tended to improve litter performance.     

Food Sorting by Collared Lemmings (Dicrostonyx groenlandicus) and Prairie Voles (Microtus ochrogaster): A Cautionary Note for Digestibility Studies

Small herbivores are often confronted with poor quality diets; in response to this situation, they may sort their food to increase diet quality. Neutral detergent fiber (NDF) levels were measured in three pelleted diets fed to collared lemmings (Dicrostonyx groenlandicus) and prairie voles (Microtus ochrogaster) and compared to levels in orts collected from the same diets and animals. Lemmings sorted and discarded the fibrous parts of food pellets on all three diets (17.3% to 25.9% higher NDF in orts), whereas voles sorted out fibrous particles on only one diet. Calculations of NDF digestibility were significantly reduced by particle sorting (up to 16.9% decrease in digestibility). In reviewing the literature, we found that in more than half of studies examined, orts may not have been analyzed for these differences. Researchers must carefully consider such effects, especially when conducting digestibility studies with herbivores on pelleted diets.     

Cell Wall Composition and Ruminant Digestibility of Various Maize Tissues Across Development

Maize stover, including stalks, leaves, and cobs, has potential utility as a cellulosic biofeedstock. Understanding how total stover ethanol potential is affected by the proportion and quality of major plant components would facilitate the genetic improvement of stover quality and inform decisions regarding which plant parts should be targeted for harvesting. Our objectives were to determine how the proportion and composition of plant components affected ethanol potential and whether there are early season predictors of stover quality at maturity. Twenty-three hybrids were evaluated including 20 from a factorial mating design between five silage inbred lines and four commercial inbreds and a brown-midrib3, a Leafy1, and a commercial grain hybrid checks. Plants were harvested and dissected into component parts at developmental stages vegetative 3, vegetative 12, reproductive 3, and reproductive 6 (R6). Tissues were evaluated for acid detergent fiber (ADF), neutral detergent fiber (NDF), and NDF digestibility (NDFD). Stalk was the largest fraction of whole plant dry matter (46.2%) and had the lowest NDFD (3,750 g/kg) at R6. No relationship was found between stalk ADF at early developmental stages and whole plant ADF at R6, suggesting that quality at early developmental stages is not indicative of quality at physiological maturity. Differences were observed among hybrids for ADF and NDF for most plant parts evaluated. Hybrid-by-developmental stage and hybrid-by-plant part interactions were statistically significant. This indicates that there is minimal opportunity to identify superior hybrids for biofuel production based on the proportion of total biomass represented by a plant part and its quality at early developmental stages. Maximum conversion efficiency is attained when leaves are harvested compared to other tissue types at physiological maturity.     

Erratum to: Cell Wall Composition and Ruminant Digestibility of Various Maize Tissues Across Development

Maize stover, including stalks, leaves, and cobs, has potential utility as a cellulosic biofeedstock. Understanding how total stover ethanol potential is affected by the proportion and quality of major plant components would facilitate the genetic improvement of stover quality and inform decisions regarding which plant parts should be targeted for harvesting. Our objectives were to determine how the proportion and composition of plant components affected ethanol potential and whether there are early season predictors of stover quality at maturity. Twenty-three hybrids were evaluated including 20 from a factorial mating design between five silage inbred lines and four commercial inbreds and a brown-midrib3, a Leafy1, and a commercial grain hybrid checks. Plants were harvested and dissected into component parts at developmental stages vegetative 3, vegetative 12, reproductive 3, and reproductive 6 (R6). Tissues were evaluated for acid detergent fiber (ADF), neutral detergent fiber (NDF), and NDF digestibility (NDFD). Stalk was the largest fraction of whole plant dry matter (46.2%) and had the lowest NDFD (375.0 g/kg) at R6. No relationship was found between stalk ADF at early developmental stages and whole plant ADF at R6, suggesting that quality at early developmental stages is not indicative of quality at physiological maturity. Differences were observed among hybrids for ADF and NDF for most plant parts evaluated. Hybrid-by-developmental stage and hybrid-by-plant part interactions were statistically significant. This indicates that there is minimal opportunity to identify superior hybrids for biofuel production based on the proportion of total biomass represented by a plant part and its quality at early developmental stages. Maximum conversion efficiency is attained when leaves are harvested compared to other tissue types at physiological maturity.