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This experiment was conducted to assess the effects of quinoa straw combined with alfalfa hay and corn straw on the in vitro fermentation characteristics of sheep rumen. Six diets with a ratio of concentrate, quinoa straw, alfalfa hay, or corn straw at 40: 20: 40, 40: 30: 30, and 40: 40: 20 were set for in vitro fermentation. The gas production (GP) of fermentation was collected at 0, 2, 4, 6, 8, 12, 24, and 48 hours. After fermentation, the supernatant and residues were collected for pH, dry matter degrada tion rate (DMD), organic matter degradation rate (OMD), and ammonia nitrogen (NH3-N) content measure ment, and which were used for calculating the single combined effect index (SFAEI) and multicombined effect index (MFAEI). The results showed that the rapid gas production part (a), 48 hour gas production (GP48 h), OMD, and NH3-N of the combination of concentrate + quinoa straw + alfalfa hay were higher than those of the combination of concentrate + quinoa straw + corn straw. The corresponding index and comprehen sive combination effect index of the combination of concentrate + quinoa straw + alfalfa hay were higher than those of the combination of concentrate + quinoa straw + corn straw. The optimal combination ratio of concentrate + quinoa straw + alfalfa hay was 40: 20: 40, and the optimal combination ratio of concentrate + quinoa straw + corn straw was 40: 20: 40. [ABSTRACT FROM AUTHOR]

Simple Summary: Moringa oleifera and Chlorella vulgaris microalgae have a good balance of amino acids with high protein contents; however, complementary and synergic effects between proteins can improve their nutritive value compared to the individual additive. Replacing a concentrate mixture at 20% to 40% levels with a mixture of M. oleifera and microalgae improved nutrient digestibility, ruminal fermentation characteristics, milk production, composition and the fatty acid profile of goats. Inclusion of M. oleifera and microalgae mixture to partially replace concentrates may enhance milk production performance and milk quality without affecting animal health. Exploring suitable alternatives for high-cost concentrate feeds is a critical factor for successful livestock production. The present experiment aimed to evaluate the dietary inclusion of Moringa oleifera silage and Chlorella vulgaris microalgae (at 1% of total diet, DM basis) in a quintuplicate 3 × 3 Latin square design for milk production performance, nutrient utilization and ruminal fermentation in Damascus goats. Fifteen lactating Damascus goats were divided into three groups to be fed a diet composed of a concentrate mixture and rice straw at 60:40 (DM basis) in the control group and fed for 30 days in each period. The concentrate mixture in the control treatment was replaced with M. oleifera silage and C. vulgaris microalgae at 20% (MA20 treatment) or 40% (MA40 treatment). Treatments did not affect total feed intake but increased (p < 0.01) crude protein (CP) and fiber intakes while decreasing nonstructural carbohydrates intake. The digestibility of CP and acid detergent fiber increased due to silage supplementation compared to the control treatment. Treatments increased (p < 0.05) ruminal pH and the concentrations of total volatile fatty acids, acetate, and propionate; however, they decreased (p < 0.05) the concentrations of ammonia-N. Treatments increased (p < 0.05) the concentrations of serum glucose and antioxidant capacity. Both MA20 and MA40 treatments increased the daily milk production, the concentrations of milk fat and lactose, and feed efficiency compared to the control treatment. Additionally, MA20 and MA40 treatments increased the proportions of total polyunsaturated fatty acids and total conjugated linoleic acids. It is concluded that the concentrate feed mixture in the diet of lactating goats can be replaced up to 40% (equals to 24% of total diet) with M. oleifera silage to improve feed intake and nutrient utilization, and milk production performance. [ABSTRACT FROM AUTHOR]

This study was conducted to evaluate the effects of replacing soybean meal (SBM) with unfermented and microbially fermented yellow wine lees (YWL) mix on the in vitro rumen fermentation characteristics of substrate mixtures. Both types consisting of YWL at 400 g/kg were included in the mixtures at different ratios (1:0, 1:1, 1:2, 1:5 and 0:1, w/w) to replace SBM. Microbial fermentation of YWL did not have a negative impact on gas value (p> .05), increased microbial protein (MCP, p

Single concentrate feeds are mixed together forming compound feeds for cattle. However, knowledge regarding the potential interactions (associative effects) between the feeding values of single feeds in compound feeds is lacking. The main objective of the present study was to evaluate ruminal fermentation characteristics and feeding values of eight industrially produced compound feeds in mash form from their constituent single feeds for dairy cows through in vitroassays. Additivity was given for gas production (GP), digestibility of organic matter (dOM) and utilisable CP at the duodenum (uCP). Additivity of CP fractions (determined using the Cornell Net Carbohydrate and Protein System (CNCPS)) was dependent on the fraction and compound feed type; however, the effective degradation calculated from CP fractions (EDCNCPS) showed additivity. Additivity was not given for intestinal digestibility of rumen-undegraded protein (IDRUP) for five out of eight compound feeds. Precise calculation of metabolisable energy (ME) of compound feeds from ME of single feeds was possible when using the same ME equations for all single and compound feeds. Compound feeds are often provided in pellet form; therefore, our second objective was to evaluate the effects of pelleting on ruminal fermentation characteristics and feeding values of compound feeds. Pelleting affected GP at 24 h (GP24; up to 2.4 ml/200 mg DM), dOM (up to 2.3 percentage point (pp)) and ME (up to 0.3 MJ/kg DM), but these differences were overall small. More considerable effects of pelleting were observed for uCP, which was increased in all compound feeds except the two with the highest CP concentrations. The IDRUPwas lower in most compound feeds following pelleting (up to 15 pp). Pelleting also affected CP fractions in a non-systematic way. Overall, the effects of pelleting were not considerable, which could be because pelleting conditions were mild. Our third objective was to compare in situruminal CP degradation (EDIN_SITU) of compound feeds with ED using two prediction methods based on CP fractions. EDIN_SITUreference data were obtained from a companion study using the same feeds. Prediction accuracy of EDIN_SITUand EDCNCPSwas variable and depended on the compound feed and prediction method. However, future studies are needed as to date not enough data are published to draw overall conclusions for the prediction of EDIN_SITUfrom CP fractions.

The objective of this study was to estimate the amount of post-rumen crude protein (prCP), a precursor to metabolisable protein for ruminants, of feeds and feed mixtures using an in situ and in vitro method, and to contrast the results of both approaches. For this, 34 samples were examined: 9 feeds, 13 feed mixtures made thereof and 12 feed mixtures provided by commercial dairy farms. As a minor aspect, additivity of protein values from feeds was evaluated by comparing measured and calculated values of feed mixtures. Effective prCP was calculated for assumed rumen passage rates (k) of 0.05 h−1 (prCP5) and 0.08 h−1 (prCP8) by in situ measurements of rumen undegraded CP and fermented organic matter (FOM) assuming an efficiency of 181 g microbial CP/kg FOM. Additionally, effective prCP in vitro was estimated using the modified Hohenheim gas test (modHGT) through incubation in rumen-fluid buffer solution for 8 and 24 h followed by ammonia distillation. In vitro estimations were highly correlated with in situ values for both passage rates (k = 0.05 h−1: p < 0.001, R2 = 0.68; k = 0.08 h−1: p < 0.001, R2 = 0.76). The in vitro method yielded higher values for effective prCP than the in situ approach with 29 g/kg OM (k = 0.05 h−1) and 37 g/kg OM (k = 0.08 h−1) on average for all samples. Small positive associative effects – reflecting non-additivity – were found, averaging at 2.2 g prCP8/kg OM (p < 0.05) for the in situ and 10.7 g prCP8/kg OM (p < 0.001) for the in vitro approach. Due to the need of an assumption of a certain value for microbial efficiency in situ, effective prCP might be more accurately estimated in vitro, accounting for nutrient-specific efficiencies as well as interactions between carbohydrate and protein degradation by rumen microbes. Furthermore, the modHGT highlighted associative effects more pronounced and seems suitable as a routine method due to the comparably low effort and high sample throughput. The potential of the modHGT to determine the protein value of feeds could be demonstrated by our study. [ABSTRACT FROM AUTHOR]

Copyright of Acta Prataculturae Sinica is the property of Acta Prataculturae Sinica Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Acta Prataculturae Sinica is the property of Acta Prataculturae Sinica Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Agricultural Science & Technology (1008-0864) is the property of Journal of Agricultural Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

There is a lot of evidence that chicory could be a highly palatable and nutritious source of forage for ruminants, well adapted to climate change and dry conditions in summer, thanks to its resistance to drought and high water content. This study aimed to describe the effect of incorporating chicory to ryegrass or to a ryegrass–white clover mixture on feeding behaviour, digestive parameters, nitrogen (N) balance and methane (CH4) emissions in sheep. In total, three swards of ryegrass, white clover and chicory were established and managed in a manner ensuring the forage use at a constant vegetative stage throughout the experiment. In all, four dietary treatments (pure ryegrass; binary mixture: 50% ryegrass–50% chicory; ternary mixture: 50% ryegrass–25% white clover–25% chicory; and pure chicory) were evaluated in a 4×4 replicated Latin square design with eight young castrated Texel sheep. Each experimental period consisted of an 8-day diet adaptation phase, followed by a 6-day measuring phase during which intake dynamics, chewing activity, digestibility, rumen liquid passage rate, fermentation end-products, N balance and CH4 emissions were determined. Data were analysed using a mixed model and orthogonal contrasts were used to detect the potential associative effects between ryegrass and chicory. The daily voluntary dry matter intake was lower for pure ryegrass than for diets containing chicory (P

Exploring suitable alternatives for high-cost concentrate feeds is a critical factor for successful livestock production. The present experiment aimed to evaluate the dietary inclusion of Moringa oleifera silage and Chlorella vulgaris microalgae (at 1% of total diet, DM basis) in a quintuplicate 3 × 3 Latin square design for milk production performance, nutrient utilization and ruminal fermentation in Damascus goats. Fifteen lactating Damascus goats were divided into three groups to be fed a diet composed of a concentrate mixture and rice straw at 60:40 (DM basis) in the control group and fed for 30 days in each period. The concentrate mixture in the control treatment was replaced with M. oleifera silage and C. vulgaris microalgae at 20% (MA20 treatment) or 40% (MA40 treatment). Treatments did not affect total feed intake but increased (p < 0.01) crude protein (CP) and fiber intakes while decreasing nonstructural carbohydrates intake. The digestibility of CP and acid detergent fiber increased due to silage supplementation compared to the control treatment. Treatments increased (p < 0.05) ruminal pH and the concentrations of total volatile fatty acids, acetate, and propionate; however, they decreased (p < 0.05) the concentrations of ammonia-N. Treatments increased (p < 0.05) the concentrations of serum glucose and antioxidant capacity. Both MA20 and MA40 treatments increased the daily milk production, the concentrations of milk fat and lactose, and feed efficiency compared to the control treatment. Additionally, MA20 and MA40 treatments increased the proportions of total polyunsaturated fatty acids and total conjugated linoleic acids. It is concluded that the concentrate feed mixture in the diet of lactating goats can be replaced up to 40% (equals to 24% of total diet) with M. oleifera silage to improve feed intake and nutrient utilization, and milk production performance.

This study was conducted to evaluate the effects of replacing soybean meal (SBM) with unfermented and microbially fermented yellow wine lees (YWL) mix on the in vitro rumen fermentation characteristics of substrate mixtures. Both types consisting of YWL at 400 g/kg were included in the mixtures at different ratios (1:0, 1:1, 1:2, 1:5 and 0:1, w/w) to replace SBM. Microbial fermentation of YWL did not have a negative impact on gas value (p>.05), increased microbial protein (MCP, p <.01) and in vitro crude protein (CP) digestibility (p <.01), and improved the efficiency of nitrogen utilisation (p <.01). The ratio of YWL replacing SBM had linear and quadratic effects on gas production (GP, p <.01), the rate of GP (p <.01), MCP (p <.01), total volatile fatty acids (VFAs, p <.01), in vitro CP digestibility and efficiency of nitrogen utilisation (p <.01), with the optimal ratio at 1:1. The in vitro digestibilities of dry matter and organic were slightly (p <.01) reduced with the increasing ratio of YWL. Besides, positive associative effects were observed on GP parameters, VFA and MCP at some replacement ratios. Considering the in vitro rumen characteristics and their associative effects, the optimal ratio at which to replace SBM with microbially fermented YWL was indicated to be 1:1. The in vitro rumen fermentation characteristics performed better with microbially fermented than unfermented yellow wine lees (YWL) replacing soybean meal (SBM). The positive associative effects were observed on gas production parameters, volatile fatty acid and microbial protein at replacing ratio of 1:1. The optimal ratio at which to replace SBM with microbially fermented YWL was 1:1. [ABSTRACT FROM AUTHOR]

Within‐population variation in the traits underpinning reproductive output has long been of central interest to biologists. Since they are strongly linked to lifetime reproductive success, these traits are expected to be subject to strong selection and, if heritable, to evolve. Despite the formation of durable pair bonds in many animal taxa, reproductive traits are often regarded as female‐specific, and estimates of quantitative genetic variation seldom consider a potential role for heritable male effects. Yet reliable estimates of such social genetic effects are important since they influence the amount of heritable variation available to selection. Based on a 52‐year study of a nestbox‐breeding great tit (Parus major) population, we apply "extended" bivariate animal models in which the heritable effects of both sexes are modeled to assess the extent to which males contribute to heritable variation in seasonal reproductive timing (egg laying date) and clutch size, while accommodating the covariance between the two traits. Our analyses show that reproductive timing is a jointly expressed trait in this species, with (positively covarying) heritable variation for laydate being expressed in both members of a breeding pair, such that the total heritable variance is 50% larger than estimated by traditional models. This result was robust to explicit consideration of a potential male‐biased environmental confound arising through sexually dimorphic dispersal. In contrast to laydate, males' contribution to heritable variation in clutch size was limited. Our study thus highlights the contrasting extent of social determination for two major components of annual reproductive success, and emphasizes the need to consider the social context of what are often considered individual‐level traits. [ABSTRACT FROM AUTHOR]

Single concentrate feeds are mixed together forming compound feeds for cattle. However, knowledge regarding the potential interactions (associative effects) between the feeding values of single feeds in compound feeds is lacking. The main objective of the present study was to evaluate ruminal fermentation characteristics and feeding values of eight industrially produced compound feeds in mash form from their constituent single feeds for dairy cows through in vitro assays. Additivity was given for gas production (GP), digestibility of organic matter (dOM) and utilisable CP at the duodenum (uCP). Additivity of CP fractions (determined using the Cornell Net Carbohydrate and Protein System (CNCPS)) was dependent on the fraction and compound feed type; however, the effective degradation calculated from CP fractions (EDCNCPS) showed additivity. Additivity was not given for intestinal digestibility of rumen-undegraded protein (IDRUP) for five out of eight compound feeds. Precise calculation of metabolisable energy (ME) of compound feeds from ME of single feeds was possible when using the same ME equations for all single and compound feeds. Compound feeds are often provided in pellet form; therefore, our second objective was to evaluate the effects of pelleting on ruminal fermentation characteristics and feeding values of compound feeds. Pelleting affected GP at 24 h (GP24; up to 2.4 ml/200 mg DM), dOM (up to 2.3 percentage point (pp)) and ME (up to 0.3 MJ/kg DM), but these differences were overall small. More considerable effects of pelleting were observed for uCP, which was increased in all compound feeds except the two with the highest CP concentrations. The IDRUP was lower in most compound feeds following pelleting (up to 15 pp). Pelleting also affected CP fractions in a non-systematic way. Overall, the effects of pelleting were not considerable, which could be because pelleting conditions were mild. Our third objective was to compare in situ ruminal CP degradation (EDIN_SITU) of compound feeds with ED using two prediction methods based on CP fractions. EDIN_SITU reference data were obtained from a companion study using the same feeds. Prediction accuracy of EDIN_SITU and EDCNCPS was variable and depended on the compound feed and prediction method. However, future studies are needed as to date not enough data are published to draw overall conclusions for the prediction of EDIN_SITU from CP fractions. [ABSTRACT FROM AUTHOR]

Dairy cows are commonly fed compound feed concentrates, whose accurate formulation relies on the additivity of ruminal degradation characteristics of single feeds, and the absence of associative effects. The main aim of this study was to evaluate the additivity of single feeds in compound feeds made thereof. Twelve single feeds were used to produce eight compound feeds in mash and pelleted form. Samples of single and compound feeds were incubated in situ in three ruminally fistulated dairy cows, and effective ruminal degradation (ED) of CP and starch (ST) was computed. The ED values of examined compound feeds could be, in most cases, accurately calculated from ED values of single feeds. Observed EDCP values were significantly lower than that calculated, but differences were overall small and not exceeded 5% points. No significant differences were observed between calculated and observed EDST. The study also examined the effects of pelleting of compound feeds on in situ degradation. Pelleting significantly increased EDCP (up to 8% points), and EDST (up to 4% points) of most compound feeds. This could have been caused by the pelleting process increasing the proportion of fine feed particles with fast disappearance from the bags. It was concluded that small associative effects between the examined single feeds could be disregarded when formulating compound feeds for dairy cows, and that additivity of EDCP and EDST can be assumed in most cases. [ABSTRACT FROM AUTHOR]

Copyright of Acta Prataculturae Sinica is the property of Acta Prataculturae Sinica Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

There is a lot of evidence that chicory could be a highly palatable and nutritious source of forage for ruminants, well adapted to climate change and dry conditions in summer, thanks to its resistance to drought and high water content. This study aimed to describe the effect of incorporating chicory to ryegrass or to a ryegrass–white clover mixture on feeding behaviour, digestive parameters, nitrogen (N) balance and methane (CH4) emissions in sheep. In total, three swards of ryegrass, white clover and chicory were established and managed in a manner ensuring the forage use at a constant vegetative stage throughout the experiment. In all, four dietary treatments (pure ryegrass; binary mixture: 50% ryegrass–50% chicory; ternary mixture: 50% ryegrass–25% white clover–25% chicory; and pure chicory) were evaluated in a 4×4 replicated Latin square design with eight young castrated Texel sheep. Each experimental period consisted of an 8-day diet adaptation phase, followed by a 6-day measuring phase during which intake dynamics, chewing activity, digestibility, rumen liquid passage rate, fermentation end-products, N balance and CH4 emissions were determined. Data were analysed using a mixed model and orthogonal contrasts were used to detect the potential associative effects between ryegrass and chicory. The daily voluntary dry matter intake was lower for pure ryegrass than for diets containing chicory (P <0.001) and increased quadratically from 1.39 to 1.74 kg/day with increasing proportion of chicory. Huge positive quadratic effects (P <0.001) between ryegrass and chicory were detected on eating time and eating rate just after feeding indicating an increase of the motivation to eat with mixtures, whereas rumination activity decreased linearly with the proportion of chicory (P <0.001). The organic matter digestibility was similar among treatments (around 80%), but a strong positive quadratic P <0.001) effect was observed on liquid passage rate suggesting that chicory allowed fast particle breakdown in the rumen. Animals fed with the ryegrass–white clover–chicory mixture had the higher urinary N losses (P <0.001), whereas retained N per day or per g N intake was greater when the proportion of chicory was at least 50% (P <0.001) being ~40% greater than for the other treatments. The CH4 yield was lower with pure chicory than with the other treatments (P <0.001) for which emissions were similar. In conclusion, mixing ryegrass and chicory in equal proportions produces a synergy on voluntary intake and an improved N use efficiency likely due to complementarity in chemical composition, increased motivation to eat and faster ruminal particle breakdown. [ABSTRACT FROM AUTHOR]

Biotic and abiotic stresses have been making it difficult to maintain the rates of genetic gains in forest tree breeding. Planting a mixture of genotypes or clonal composites can be an alternative to increase the security of forest plantations. The formation of clonal composites is complex due to inter-genotypic competition and indirect genotypic effects that can affect the efficiency of genetic selection. This study aims to understand how indirect genotypic effects can impact the response to selection and how the stand composition can be used to explore these effects and enhance forest yield. We used two clonal trials of eucalyptus hybrids implanted in a randomized complete block design with 24 replications, containing a single tree per plot evaluated for mean annual increment at 3 and 6 years. We focused on partitioning the genotypic variation into direct and indirect genotypic effects based on competition intensity factors. We identified aggressive, homeostatic, and sensitive clones based on the magnitude of indirect genotypic effects. Considering indirect genotypic effects, for mean annual increment, the total heritability decreased from 0.25 to 0.10 for 3 years and from 0.30 to 0.14 for 6 years, respectively. We proposed a workflow that uses the direct and indirect genotypic effects to predict the mean values for clonal composite combinations and to select the one with the highest yield. Our methodology considered spatial variation and interplot competition that can affect the total heritable estimates and response to selection in forest trials. The clones were classified as aggressive, homeostatic, and sensitive, according to their deviation from the indirect genotypic effects means. Our methodology enabled the extraction of useful information and predict many clonal composites' performance, which can be used in recommending genotypes to be planted in mixtures. • The heritabilities are overestimated by not considering indirect genotypic effects. • The trade-off between direct and indirect genotypic effects must be considered. • A method for predicting high-performance clonal composites was proposed. • Total genotypic values were used to identify high-performance clonal composites. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the associative effects of rice straw with timothy hay and corn grain. Using an automated gas production system, in vitro ruminal fermentation was studied for six substrates: 100% rice straw, 100% timothy hay, 100% corn grain, 50% rice straw and 50% timothy hay, 50% rice straw and 50% corn grain, and 50% rice straw, 25% timothy hay, and 25% corn grain. Incubation was performed in three batches with different rumen fluids to assess the in vitro ruminal gas production kinetics and rumen parameters (pH, NH3-N, volatile fatty acid (VFA), and true dry matter digestibility (TDMD)). The associated effects were tested by comparing the observed values of the composited feeds and the weighted means of individual feeds. There was a significant increase in NH3-N when rice straw was fermented with timothy hay, corn grain, or both (p < 0.05). TDMD increased when corn grain was co-fermented, and the total gas and VFA production increased when all three feeds were co-fermented. We conclude that the feed value of rice straw increases when fed to animals along with timothy hay and corn grain.

The study was aimed to evaluate the associative effects of mixtures of stylosanthe (Stylosanthes guianensis) and king grass (Pennisetum purpureum × P. americanum cv. Reyan No. 4) silage at different ratios using in vitro gas production technique. Three stylosanthes (S. guianensis Sw. Reyan No.2, S2; S. guianensis Sw. Reyan No.20, S20; S. guianensis Sw. Reyan No.21, S21) were mixed with king grass silage (K) at different ratios (0:100, 10:90, 20:80, 40:60, 50:50, 100:0) and their associative effects were evaluated using in vitro gas technique. The results showed that under the controlled conditions, addition of the mixtures of stylosanthes and king grass silage could improve in vitro gas production (GP), in vitro dry matter digestibility (IVDMD) and microbial protein (MP) and promote the vitality of rumial microbes. In addition, most mixtures of stylosanthes and king grass silage showed positive associative effects and the mixtures at ratio of 20:80 had the best associative effect based on the synthetically associative effects index (SAEI). [ABSTRACT FROM AUTHOR]

Sexual reproduction is inherently interactive, especially in animal species such as humans that exhibit extended pair bonding. Yet we have little knowledge of the role of male characteristics and their evolutionary impact on reproductive behavioural phenotypes, to the extent that biologists typically consider component traits (e.g. reproductive timing) as female-specific. Based on extensive genealogical data detailing the life histories of 6435 human mothers born across four centuries of modern history, we use an animal modelling approach to estimate the indirect genetic effect of men on the reproductive phenotype of their partners. These analyses showthat awoman's reproductive timing (age at first birth) is influenced by her partner's genotype. This indirect genetic effect is positively correlated with the direct genetic effect expressed in women, such that total heritable variance in this trait is doubled when heritable partner effects are considered. Our study thus suggests that much of the heritable variation in women's reproductive timing ismediated via partner effects, and that the evolutionary potential of this trait is far greater than previously appreciated. [ABSTRACT FROM AUTHOR]

Herein we report novel approaches to the molecular imprinting of proteins utilizing templates sizing around 10 nm and some 100 nm. The first step comprised synthesizing nanoparticles of molecularly imprinted polymers (MIP) towards bovine serum albumin (BSA) and characterizing them according to size and binding capacity. In a second step, they were utilized as templates. Quartz crystal microbalances (QCM) coated with MIP thin films based on BSA MIP nanoparticles lead to a two-fold increase in sensor responses, compared with the case of directly using the protein as the template. This also established that individual BSA molecules exhibit different "epitopes" for molecular imprinting on their outer surfaces. In light of this knowledge, a possible MIP-based biomimetic assay format was tested by exposing QCM coated with BSA MIP thin films to mixtures of BSA and imprinted and non-imprinted polymer (NIP) nanoparticles. At high protein concentrations (1000 ppm) measurements revealed aggregation behavior, i.e., BSA binding MIP NP onto the MIP surface. This increased sensor responses by more than 30% during proof of concept measurements. At lower a BSA concentration (500 ppm), thin films and particles revealed competitive behavior. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the associative effects between fresh perennial ryegrass and fresh white clover on intake and digestion in sheep. Five proportions of ryegrass and white clover, ranging from 0 to 1 in 0·25 increments ( DM basis), were allocated to two groups of five sheep according to a replicated 5 × 5 Latin square design, and intake behaviour and digestive parameters including methane ( CH4) emissions were measured. Feeding behaviour was affected through increased forage intake when the proportion of white clover was increased, and there were positive associative effects on intake, eating time and eating rate during the main meals consumed immediately after feed was given. These effects seemed to be related to a greater motivation to eat, rather to more efficient digestion, as no difference on DM digestibility (average 766 g kg−1) was detected. There were no differences in CH4 yield (average 18·1 g kg−1 DM intake) among the treatments. The optimal proportion of white clover fed with ryegrass to optimize intake and digestion was between 0·25 and 0·50. These results indicate that mixing perennial ryegrass and white clover positively affects forage intake in sheep and their motivation to eat. [ABSTRACT FROM AUTHOR]

Effects of dietary concentrate level and grass hay source were determined to evaluate a method (www2.luresext.edu/goats/research/suppconc.html) of predicting negative associative effects between feedstuffs in Boer goat wethers. Forage DM intake (g/kg BW0.75) was similar (P = .157) between growing and yearling wethers (34.9 and 30.8) and ranked 0 and 15 > 30 > 45 g/kg BW0.75of concentrate dry matter (48.5, 41.8, 25.9, and 15.2, respectively). Age and concentrate level interacted in neutral detergent fibre digestibility (57.3%, 60.6%, 61.4%, and 58.4% for growing and 56.6, 62.9, 56.8, and 30.0% for yearling wethers with 0, 15, 30, and 45 g/kg BW0.75, respectively). There was a tendency (P = .074) for an interaction in metabolizable energy (ME) intake between age and concentrate level (361, 530, 634, and 709 for growing and 363, 547, 541, and 555 kJ/kg BW0.75for yearling wethers with 0, 15, 30, and 45 g/kg BW0.75); values predicted for treatments with concentrate were 563, 631, and 619 for growing and 575, 684, and 697 kJ/kg BW0.75for yearling wethers with 15, 30, and 45 g/kg BW0.75, respectively. In conclusion, ME intake was accurately predicted for the low level of concentrate with both animal types and the moderate level with growing wethers. [ABSTRACT FROM PUBLISHER]

The effects of supplementation with different protein: carbohydrate ratios on body composition, carcass characteristics and protein and energy deposition efficiency of young were assessed. Twenty-four Nellorecalves (132.5 ± 5.5 kgand 90-150 days of age) were kept on pasture for a 430 day experimental period. The treatments were: Control = mineral mixture only; HPHC = high-protein and high-carbohydrate supplement; HPLC = high-protein and low-carbohydrate supplement; LPHC = low-protein and high-carbohydrate supplement; LPLC = low-protein and low-carbohydrate supplement. Four animals at begning and 20 animal at end of experiment were slaughtered to evaluate the carcass composition. Control bulls had the lowest (p < 0.05) intake of ME (9.8 Mcal day-1) with no difference (p > 0.05) between supplemented bulls (13 Mcal day-1). Although non-supplemented bulls had less (p < 0.05) retained protein, retained energy (RE), body weight gain and dressing percentage, differences were not observed (p > 0.05) between supplemented bulls. High-carbohydrate supplements were associated with more (p < 0.05) RE (596.2 Mcal) than low-carbohydrate supplements (515.5 Mcal). Differences were not found (p > 0.05) in the energy efficiency between the groups. Therefore, supplementation increases the intake and retention of protein and energy without changing the retention efficiency.

The aim of this study was to evaluate the effects of the association between red clover (RC; Trifolium pratense ) and a tropical grass (kikuyu grass) on the proteolysis of ensiled material and the in vitro degradation of protein and organic matter. Red clover and kikuyu grass were ensiled in the following proportions: 0:1000, 250:750, 500:500, 750:250, and 1000:0 g/kg of dry matter (DM). The fraction of rapidly degradable protein, the ammonia nitrogen (NH 3 -N) content of the silo, the in vitro protein degradation, and the degradation rate decreased linearly (P < 0.001) as the RC content in the ensiled material increased. Cumulative gas production after 24 h incubation showed a positive quadratic effect when RC was increased to 500 g/kg (P < 0.001). The silages with the highest RC content reduced proteolysis more effectively during ensiling and ruminal fermentation. Inter-species synergistic effects positively affected in vitro gas production, which was optimal when RC and kikuyu grass were ensiled in the same proportions as that of total DM. [ABSTRACT FROM AUTHOR]

Associative effects between plants included in some mixtures with tropical and temperate species, which are able to grow in a wide range of temperature, deserve to be better investigated. The aim of this work was to assess the in vitro rumen fermentation characteristics when a tropical (peanut, Arachis pintoi ) or temperate legume (sainfoin, Onobrychis viciifolia ) with condensed tannins (CT), or a temperate legume without CT (alfalfa, Medicago sativa ), were mixed with a tropical (axonopus, Axonopus catharinenses ) or a temperate grass (tall fescue, Festuca arundinacea ). Different proportions of each legume were mixed with each grass (in%, on dry matter (DM) basis, 0:100, 25:75, 50:50 75:25 and 100:0), and were tested using an in vitro rumen fermentation assay. The crude protein content in both tropical and temperate grasses ranged from 100 to 120 g/kg DM, but the aNDF content was much higher in the tropical (617 g/kg DM) than in the temperate grass (464 g/kg DM). The ADF (+214 g/kg DM) and lignin (+46.2 g/kg DM) content was much higher in the alfalfa when compared with the average of two other legumes. Positive quadratic effects were detected on in vitro DM disappearance (IVDMD), total gas production, and volatile fatty acids production, when alfalfa was mixed with axonopus, but similar response was not observed when alfalfa was mixed with tall fescue. The IVDMD and total gas production linearly increased when the proportion of peanut or sainfoin increased in the mixtures containing axonopus, but did not change when these legumes were mixed with tall fescue. The ammonia production increased when the proportion of legume increased in all mixtures. Reductions on ammonia and methane (CH 4 ) productions were observed in mixtures containing sainfoin without the presence of polyethylene glycol (PEG) compared to fermentation done with PEG, but this response was not observed in the mixtures containing peanut. We conclude that complementarities in terms of energy and protein content can create favourable conditions leading to positive associative effects on rumen digestive parameters when legume species were mixed with axonopus, but not when they are mixed with tall fescue, probably due to different fibre content of grasses. The CT of sainfoin allow to reduce ruminal protein degradability and mitigate CH 4 emissions per kg of DM, while the CT content of peanut is not enough to have the same effects. [ABSTRACT FROM AUTHOR]

The effect of the forage source on ruminal fermentation in vitro was investigated for fine (F) and coarse (C) milled diets, using a modified Hohenheim gas production test and a semi-continuous rumen simulation technique (Rusitec). It was hypothesised that the replacement of maize silage by grass silage might lead to associative effects and that interactions related to particle size variation could occur. Five diets with a maize silage to grass silage ratio of 100 : 0, 79 : 21, 52 : 48, 24 : 76 and 0 : 100 differed in their content of CP and carbohydrate fractions, as well as digestible crude nutrients, derived from a digestibility trial with wether sheep. For in vitro investigations, the diets were ground to pass a sieve of either 1 mm (F) or 4 mm (C) perforation. Cumulative gas production was recorded during 93 h of incubation and its capacity decreased with increasing proportion of grass silage in the diet. Across all diets, gas production was delayed in C treatments compared with F treatments. Degradation of crude nutrients and detergent fibre fractions was determined in a Rusitec system. Daily amounts of NH3-N and short-chain fatty acids (SCFA) were measured in the effluent. Degradation of organic matter (OM) and fibre fractions, as well as amounts of NH3-N, increased with stepwise replacement of maize silage by grass silage. Degradability of CP was unaffected by diet composition, as well as total SCFA production. In contrast to the results of the gas production test, degradation of OM and CP was higher in C than in F treatments, accompanied by higher amounts of NH3-N and SCFA. Interactions of silage ratio and particle size were rare. It was concluded that the stepwise replacement of maize silage by grass silage might lead to a linear response of most fermentation characteristics in vitro. This linear effect was also supported by total tract digestibility data. However, further investigations with silages of variable quality seem to be necessary.

The feeding value of forage mixtures from permanent and temporary multi-species grasslands cannot always be precisely defined. Indeed, the digestibility and feed intake of a combination of forages can differ from the balanced median values calculated from forages considered separately. In order to present an overview of the associative effects between forages on digestion and intake, a literature study was carried out. The associative effects can be studied in a complementary way in vitro to test digestive interactions of a large number of mixtures and to carry out explanatory experiments, and in vivo to investigate intake and digestion at the whole animal scale. We identified three main situations in which interactions between forages can lead to associative effects on intake and digestion: (i) increased intake that can be observed with grass and legume association can be explained by fast digestion of the soluble fraction of legumes, and a higher rate of particle breakdown and passage through the rumen, (ii) increased digestion when a poor forage is supplemented by a high nitrogen content plant can be explained by stimulation of the microbial activity and (iii) modification of digestive processes in the rumen, including proteolysis and methane production when certain bioactive secondary metabolites such as tannins, saponins or polyphenol oxidase are present. According to the type and concentration of these compounds in the diet, the effects can be favourable or unfavourable on intake and digestive parameters. Reported associative effects between forages show a large variability among studies. This reflects the complexity and multiplicity of nutritional situations affecting intake and the rumen function in a given animal. In order to provide more reliable information, further accumulation of data combining in vitro and in vivo studies is required. A better understanding of the associative effects between forages could help to optimise feed use efficiency, resulting in greater productivity, a reduction of the environmental impact of animal emissions and more sustainable animal production.

The profitability of temperate dairy systems in southern Australia and New Zealand is underpinned by the efficient use of the home-grown feed-base and purchased supplements. While there are well established principles on which to devise nutritionally balanced rations for ruminants, it is evident that in grazing systems the variable supply of nutrients from forage often results in suboptimal performance compared with predicted responses. This review discusses the key factors likely to directly affect responses to supplementation in grazing systems, namely pasture supply, nutritive characteristics and intake, feeding systems, substitution, associative effects and nutrient synchrony. Intake is the primary driver for metabolisable energy (ME) and nutrient supply and uncertainties on the actual ME and nutrients supplied by pasture will remain due to variability within and between pasture types and within paddocks. It is suggested that improvements in ration formulation will require a better understanding of the kinetics of intake and digestion within the rumen and of nutrients supplied to the tissues from grazed pasture with and without supplements. Research which clearly elucidates which mechanism or mechanisms determine substitution rates with concentrate and forage supplements would be valuable. Such knowledge could also be used to develop feeding strategies that result in a reduction in the degree of substitution and, in turn, lead to higher DM and ME intake compared with existing feeding practices. This in turn would lead to a better understanding of associative effects and nutrient synchrony with benefits in better design of rations and feed-use efficiency. Temperate dairy systems in southern Australia and New Zealand are underpinned by the efficient use of the home-grown feed-base and purchased supplements. While established principles exist to nutritionally balance such rations, the variable supply of nutrients under grazing often results in suboptimal performance. This review discusses the key factors that affect responses to supplementation in grazing systems, and considers where future research may be directed to improve animal performance from pasture-based systems. [ABSTRACT FROM AUTHOR]

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Selection for improved host response to infectious disease offers a desirable alternative to chemical treatment but has proven difficult in practice, due to low heritability estimates of disease traits. Disease data from field studies is often binary, indicating whether an individual has become infected or not following exposure to an infectious disease. Numerous studies have shown that from this data one can infer genetic variation in individuals’ underlying susceptibility. In a previous study, we showed that with an Indirect Genetic Effect (IGE) model it is possible to capture some genetic variation in infectivity, if present, as well as in susceptibility. Infectivity is the propensity of transmitting infection upon contact with a susceptible individual. It is an important factor determining the severity of an epidemic. However, there are severe shortcomings with the Standard IGE models as they do not accommodate the dynamic nature of disease data. Here we adjust the Standard IGE model to (1) make expression of infectivity dependent on the individuals’ disease status (Case Model) and (2) to include timing of infection (Case-ordered Model). The models are evaluated by comparing impact of selection, bias and accuracy of each model using simulated binary disease data. These were generated for populations with known variation in susceptibility and infectivity thus allowing comparisons between estimated and true breeding values. Overall the Case Model provided better estimates for host genetic susceptibility and infectivity compared to the Standard Model in terms of bias, impact and accuracy. Furthermore, these estimates were strongly influenced by epidemiological characteristics. However, surprisingly, the Case Ordered model performed considerably worse than the Standard and the Case Models, pointing towards limitations in incorporating disease dynamics into conventional variance component estimation methodology and software used in animal breeding.

Animal nutrition models can be useful to gain an understanding of factors responsible for and predict biological responses. However, specific models developed can vary among statistical methods employed, especially with relatively small datasets. In this meta-analysis study, independent variables selected by regression tree, stepwise regression, and Least Absolute Shrinkage and Selection Operator (LASSO) analyses were compared. The database consisted of 135 treatment means (weighted by the number observations) from 25 publications in which goats consumed forage ad libitum with or without supplementation and was divided into three subsets of forage with a crude protein (CP) concentration < 6% (Low; n = 46), 6-10% (Moderate; n = 50), and > 10% (High; n = 39). Regression tree analysis was conducted with rpart of the R statistical programming language and stepwise regression (proc stepwise) and LASSO (proc glmselect) were conducted with SAS. The target variable was forage metabolizable energy (ME) intake relative to metabolic body weight (BW0.75) and potential predictor variables were supplement ME intake also scaled to BW0.75, forage organic matter (OM) digestibility and neutral detergent fiber (NDF) concentration, and supplement concentrations of ME and CP. As shown in Table 1, supplement ME intake was selected with each method. Based on the order of selection, forage NDF concentration had larger impact than supplement ME intake with the Low dataset, whereas supplement ME intake was most important with Moderate and High datasets. Among the statistical methods evaluated, selected variables varied most with the Low dataset, were similar for the Moderate dataset, and were the same for Stepwise and LASSO approaches with the High dataset. In conclusion, model development to predict feedstuff associative effects in goats requires careful attention to variable selection that is impacted by statistical method and varies with forage composition. [ABSTRACT FROM AUTHOR]

• Whole plant corn silage could be replaced with low quality corn silage in beef cattle diet. • Reasonable use of stalklage and straw is economical without reducing animal performance. • There is an associative effect among diet components on animal performance. Corn silage is an important feedstuff for cattle because of the joint provision of starch and physical effective fiber and its palatability. However, the whole plant corn silage is underproduced in some regions until today and could not be popularized in beef cattle raising. The objective of this study was to compare the feeding value, ruminal fermentation and bacterial community of a diet comprised of various corn silages or combination with wheat straw in finishing beef cattle. One hundred eighty Simmental crossbred steers were blocked (60 steers/block) on the basis of initial BW. The animals were randomly assigned to 1 of 12 identical research pens (4 pens/block; 15 steers/pen), where each of the 4 research diets was assigned to 1 pen within each block as follows: (1) the whole plant corn silage-based diet was used as the control diet (WPCS), (2) the mixed forages-based diet was formulated by replacing a portion of whole plant corn silage with wheat straw (WPCSW), (3) the corn stalklage-based diet (CS), and (4) the sweet corn stalklage-based diet (SCS). The four diets were formulated to be isonitrogenous and isoenergetic with same forage to concentrate ratio. Experimental diets were fed for 90 d; a diet digestibility trial was conducted at the end of this period. There were no effects (P = 0.596) of treatment on dry matter intake, but average daily gain was greater for steers offered the WPCS diet, intermediate with WPCSW and SCS and lowest with CS (P < 0.001). Dry matter digestibility was greater (P = 0.005) for WPCS and SCS diets than for WPCSW and CS diets. The nutrients digestibility of CS was less than observed for WPCS diet (P < 0.05). The concentrations of ruminal volatile fatty acids were highest for WPCS diet, intermediate with WPCSW diet and lowest with SCS and CS diets (P < 0.001). Diets treatment had no effect on the α-diversity of rumen bacteria in steers (P > 0.05), but only caused the change of relative abundance of Ruminococcaceae and Prevotellaceae (P = 0.036 and 0.037, respectively). In conclusion, the WPCS-based diet exhibited the highest feeding value. The SCS and WPCSW offered suitable alternatives to a WPCS based diet offered to beef cattle, with limited negative influence on growth, apparent digestibility of nutrients and ruminal bacterial microbiota. In contrast, the value of a CS-based diet was relatively poor. However, it may still be economical to substitute WPCS with relative low-quality corn silage in feedlot cattle diets. [ABSTRACT FROM AUTHOR]

Abstract: Despite cereal grains being grown on 5 continents where goats are kept, there is little information on the excretion of whole cereal grains when fed to goats. We determined the effects of various dietary treatments on whole grain and starch loss in the faeces of Angora goats. In Experiment 1 there were 4 replicates of the factorial design: (a) 2 grain types (barley, oats); (b) whole grain or processing (milled barley or rolled oats); (c) 2 roughage qualities (Persian clover hay, barley straw); and (d) 2 feeding levels (level 1, 150g/d of grain, 250g/d of roughage; level 2, 250g/d of grain, ad libitum roughage). In Experiment 2, which immediately followed Experiment 1, and aimed to detect carry over effects of previous feeding of barley straw and grain processing, feed levels were either 650g/d grain or 400g/d grain with 550g/d Persian clover hay. Data were analysed by ANOVA. In Experiment 1, processing had no effect on digestible dry matter intake. The number of whole grains lost per 100g of fresh faeces and whole grains loss as the % of grain dry matter intake were affected by an interaction between processing and roughage quality. Whole grain fed with Persian clover hay had greater grain loss than all other diets. Whole grain loss was greater with whole grain than with processed grain. Level of feeding had no effects on grain loss. In Experiment 2, more whole grains were lost in fresh faeces when fed with Persian clover hay than when fed without hay, an effect of previous feeding with barley straw reduced whole grain excretion, and more barley grains were lost than oat grain. Faecal starch was affected, with higher levels when whole barley grain was fed, particularly with Persian clover hay, or when previously fed barley straw at a high level. Feeding grain at 650g/d did not increase grain or starch excretion. Whole grains represented a small loss of grain dry matter intake in faeces, averaging 0.8% with a maximum recorded of 2.6%. Faecal concentration of the whole grains may be altered by grain size and the digestibility of the roughage component of the diet. In this study an additional cost of 3% for processing grains would not have provided economic benefits. [Copyright &y& Elsevier]

BACKGROUND: Current feed evaluation systems for dairy cattle assume that nutritive values of feed components can be added, but do not take into account possible interactions among feed components. The main objective of this study was to investigate associative effects on in vitro gas production from total mixed ration (TMR), based on grass silage and cereal concentrate, and separate TMR components. TMR was incubated with inocula of free rumen liquid (FRL) and particle-associated rumen liquid (PAL) for 48 h and donor cows were fed TMRs with three different particle sizes to evaluate their influence on associative effects. RESULTS: Associative effects on gas production largely occurred at 2 and 4 h of incubation and dissipated with time of incubation. Incubation of TMR with PAL increased ( P < 0.01) gas production compared to FRL at all incubation times; however, associative effects were not different between rumen inocula. Dietary particle size affected associative effects on gas production when TMR was incubated with FRL ( P < 0.05) compared to PAL, particularly at early hours of incubation. CONCLUSIONS: Associative effects at early incubation hours emphasise that summing the nutritive values of feedstuffs may underestimate fermentation intensity of TMR which may have implications for prediction of ruminal fermentation yield. Copyright © 2012 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

In the pig industry, male piglets are surgically castrated early in life to prevent boar taint. Boar taint is mainly caused by androstenone and skatole. Androstenone is a pheromone that can be released from the salivary glands when the boar is sexually aroused. Boars are housed in groups and as a consequence boars can influence and be influenced by the phenotype of other boars by (non-)heritable social interactions. The influence of these social interactions on androstenone is not well understood. The objective of this study is to investigate whether androstenone concentrations are affected by (non-)heritable social interactions and estimate their genetic correlation with growth rate and backfat. The dataset contained 6,245 boars, of which 4,455 had androstenone observations (68%). The average number of animals per pen was 7 and boars were housed in 899 unique pen-groups (boars within a single pen) and 344 unique compartment-groups (boars within a unique 'room' within a barn during time). Four models including different random effects, were compared for androstenone. Direct genetic, associative (also known as social genetic or indirect genetic effects), group, compartment, common environment and residual effects were included as random effects in the full model (M3). Including random pen and compartment effects (non-heritable social effects) significantly improved the model (M2) compared with including only direct, common environment and residual as random effects (Ml, P < 0.001), and including associative effects even more (M3, P < 0.001). The sum of the direct and associative variance components determines the total genetic variance of the trait. The associative effect explained 11.7% of the total genetic variance. Backfat thickness was analysed using M2 and growth using M3. The genetic correlation between backfat (direct genetic variance) and total genetic variance for androstenone was close to 0. Backfat and the direct and associative effects for androstenone had genetic correlations of 0.14 ± 0.08 and -0.25 ±0.18, respectively. The genetic correlation between total genetic variances for growth rate and androstenone was 0.33 ± 0.18. The genetic correlation between direct effects was 0.11 ± 0.09 and between associative effects was 0.42 ± 0.31. The genetic correlations and current selection towards lower backfat and greater growth rate suggest that no major change in androstenone is expected when breeding goals are not changed. For selection against boar taint and therefore also against androstenone , results recommend that at least the social environment of the boars should be considered. [ABSTRACT FROM AUTHOR]

Thirty-six male Hu lambs consuming a rice straw-based diet were used in a 60-day trial to study the associative effects of cornstarch supplementation on intake, digestion, ruminal microbial population and growth performance. All animals were fed rice straw ad libitum together with 160 g/day of rapeseed meal and supplemented with cornstarch at levels of 0 (control), 60, 120 or 180 g/day, respectively. Increment of supplementary cornstarch showed little influence on rice straw intake. Optimal growth performance and highest apparent digestibility of organic matter was achieved in the 120 g/day cornstarch group ( P < 0.05), while the digestibilities of neutral detergent fiber and crude protein were significantly decreased by 180 g/day cornstarch ( P < 0.05). Similar results were observed for carboxymethyl cellulose activity and relative populations of cellulolytic bacteria ( Ruminococcus albus, Ruminococcus flavefaciens and Fibrobacter succinogene). Blood urea nitrogen was reduced by supplementary cornstarch, indicating enhanced protein utilization efficiency. Carcass traits were all significantly improved by supplementary cornstarch. These results suggested that proper amounts of starch supplementation (within 0.5% BW) has little adverse effect on forage utilization, but could effectively improve growth performance. High levels of cornstarch, however, would decrease cellulase activity and populations of cellulolytic bacteria, and hence the digestibility of forage. [ABSTRACT FROM AUTHOR]

Abstract: Non-additive dietary effects occur when nutritional gains from a mixed diet are greater than or less than that predicted by summing the gains from individual diet items. Both positive and negative effects occur in adult slider turtles, Trachemys scripta. Such effects may also be important to juvenile T. scripta as they ontogenetically switch from carnivorous to herbivorous diets. The purpose of this study was to determine if juveniles experience non-additive effects and to assess the underlying mechanism. Two feeding trials were conducted. In Trial 1, juveniles were fed 100% duckweed, Lemna valdiviana, 100% grass shrimp, Palaemontes paludosus, or a mixed diet containing 81% duckweed and 19% shrimp. In Trial 2, juveniles were fed 100% duckweed, Lemna minor, 100% cricket, Acheta domesticus, or one of three mixed diets containing duckweed and cricket in varying percentages (22%, 39% and 66% cricket). Similar to adults, a negative non-additive effect was demonstrated on the 19% shrimp and 22% cricket diets. However, the positive effect found in adults was not observed. Intake varied dramatically between the plant and animal diets, resulting in differences in transit time that could explain the non-additive effect. These results offer some insight into understanding ontogenetic diet shifts in turtles. [Copyright &y& Elsevier]

The feeding value of forage mixtures from permanent and temporary multi-species grasslands cannot always be precisely defined. Indeed, the digestibility and feed intake of a combination of forages can differ from the balanced median values calculated from forages considered separately. In order to present an overview of the associative effects between forages on digestion and intake, a literature study was carried out. The associative effects can be studied in a complementary way in vitro to test digestive interactions of a large number of mixtures and to carry out explanatory experiments, and in vivo to investigate intake and digestion at the whole animal scale. We identified three main situations in which interactions between forages can lead to associative effects on intake and digestion: (i) increased intake that can be observed with grass and legume association can be explained by fast digestion of the soluble fraction of legumes, and a higher rate of particle breakdown and passage through the rumen, (ii) increased digestion when a poor forage is supplemented by a high nitrogen content plant can be explained by stimulation of the microbial activity and (iii) modification of digestive processes in the rumen, including proteolysis and methane production when certain bioactive secondary metabolites such as tannins, saponins or polyphenol oxidase are present. According to the type and concentration of these compounds in the diet, the effects can be favourable or unfavourable on intake and digestive parameters. Reported associative effects between forages show a large variability among studies. This reflects the complexity and multiplicity of nutritional situations affecting intake and the rumen function in a given animal. In order to provide more reliable information, further accumulation of data combining in vitro and in vivo studies is required. A better understanding of the associative effects between forages could help to optimise feed use efficiency, resulting in greater productivity, a reduction of the environmental impact of animal emissions and more sustainable animal production. [ABSTRACT FROM AUTHOR]

Abstract: In ruminant nutrition, the accuracy of predicting available energy from a total mixed ration (TMR) is limited because digestibilities of individual feedstuffs vary from predicted values in response to associative effects. To overcome this limitation, it was proposed that plant-specific real-time PCR assays could be used to predict the digestion of individual feeds within a TMR. To test this hypothesis, alfalfa and corn substrates (0.5g dry matter) were incubated in buffered rumen fluid at pH 6.8 or 5.5 for up to 48h. Regression analysis between DNA disappearance and dry matter disappearance (DMD) for only alfalfa or corn was used to predict DMD in mixed rations containing 75:25, 50:50, and 25:75 ratios of alfalfa to corn, after plant-specific DNA quantification. The actual DM remaining was compared against the total predicted DM remaining by summing the individual values predicted for alfalfa and corn in the mixed rations. The method was accurate and precise in predicting DM remaining (Concordance and Pearson correlations were 0.89 and 0.91, respectively). Differences between coefficients of the actual and total predicted DM remaining ranged between −0.081 and 0.087 or −0.08 and 0.09 when the pH was 6.8 or 5.5, respectively. Furthermore, by analyzing substrate incubated at pH 5.5, the method was tested in the presence of an associative effect (reduced pH) known to inhibit fibre digestion but have limited consequence on starch utilization. The method predicted DMD in agreement with the expected results. The DMD of alfalfa was significantly affected (P<0.05) by interactions between time and pH or between diet and pH, whereas DMD for corn was affected by time or diet (P<0.05). The presented method may lead to redefined models to more effectively predict the available energy of individual feedstuffs within a TMR. [Copyright &y& Elsevier]

Abstract: The aim of the current study was to investigate the associative effects of a cornstalk-based diet supplemented with alfalfa (Medicago sativa) hay on intake, digestibility, nitrogen (N) metabolisation, rumen environment and hematological parameters in Xiaoweihan sheep. We also investigated the optimal range of alfalfa hay to achieve positive associative effects and avoid negative effects. Xiaoweihan sheep (n =5; fitted with rumen T-cannula) were fed five cornstalk-based diets in a 5×5 Latin square design. Diets contained 0, 50, 150, 300, 450 g alfalfa, and were supplemented with 100 g concentrate, respectively. Our results suggested that supplementation of 300 g alfalfa hay reduced (P <0.05) cornstalk intake, but significantly increased dry matter (DM) intake (P <0.05). Additionally, DM digestibility of 150 g alfalfa hay supplementation was slightly higher than that noted in other diets. Metabolism studies showed 50–150 g alfalfa hay supplementation had a positive associative effect (P <0.05) on N utilization, with the greatest benefit noted with 150 g per day (P <0.05) compared to unsupplemented diets. Alfalfa supplementation (50–450 g per day) resulted in an elevated trend of ammonia nitrogen (NH3–N) with 50 or 150 g of alfalfa hay more likely to promote sheep rumen environment, with a noticeable increase (P <0.05) in serum urea nitrogen (UREAN) concentrations observed with 300 g alfalfa hay per day. Our data suggested that the optimal range to achieve beneficial effects and avoid negative effects was 150–300 g per day for cornstalk-based diets for sheep. [Copyright &y& Elsevier]

Abstract: Our objective was to study the positive effects of partial replacement of barley grain for corn in high concentrate diets on growth performance of growing lambs, and to determine the minimum amount of corn needed to produce such effects. Thirty-three male Awassi lambs weaned at 60 days of age were divided into three groups of 11 according to their live weight and offered three isonitrogenous diets. The control diet (B) contained 81 and 14% barley grain and wheat straw, respectively (DM basis). Corn grain replaced barley grain at 10 and 20% of dietary DM for low (LC) and high (HC) corn diets, respectively. Barley had a higher (P <0.05) rate of digestion (11.5%/h) compared with corn (8.3%/h). The in vitro 30-h digestion extent was also higher (P <0.05) for barley. The digestion rate for the B diet was higher (P <0.05) compared with the HC diet, whereas the value for the LC diet was intermediate. Lambs fed LC and HC diets consumed more (P >0.05) DM (average=855g/day) compared with lambs fed B diet (757g/day). DM and CP digestibilities were similar among diets and averaged 67.0 and 64.2%, respectively. Final BW, BW change and average daily gain (ADG) for lambs fed HC were higher (P <0.05) compared with B and LC. Moreover, lambs that consumed LC tended (P =0.12) to grow faster than lambs fed B. Feed to gain ratio was lower (P <0.05) for lambs fed HC (4.6) compared with B and LC (5.2). In summary, positive associative effects of partial replacement of barley with corn in high concentrate diets for fattening sheep were detected. However, a minimum of 20% replacement of dietary DM from barley with corn was needed to positively improve both performance and feed efficiency. [Copyright &y& Elsevier]

Abstract: Nonadditive interactions occur when diet items interact with one another such that the net energy or nutrient gain from a mixed diet differs from that predicted by summing the gains from individual diet components. We quantified nonadditive effects between duckweed, Lemma valdiviana, and grass shrimp, Palaemontes paludosus, in the freshwater turtle Trachemys scripta. We fed turtles 100% duckweed, 100% shrimp, and two mixed diets containing 67% duckweed, 33% shrimp and 14% duckweed, 86% shrimp (dry matter basis). During each feeding trial, we measured intake, digestibility, and transit time of the diet, and upon conclusion, short-chain fatty acid concentrations in turtle digestive tracts. Digestibility was lower on the 67% duckweed diet, but higher on the 14% diet. These apparent nonadditive interactions may be due to differences in transit time of duckweed and shrimp. We believe this is the first evidence of two diet items producing opposing nonadditive effects when fed in different ratios. [Copyright &y& Elsevier]

Nineteen feed mixtures, formulated with 16 single feeds, were used to study the influence of associative effects on utilizable crude protein (uCP) of feed mixtures. The in vitro incubation technique of Zhao and Lebzien (2000) was used for uCP determination. It was found that the in vitro -determined uCP (D-uCP) was significantly higher than the weighted uCP (W-uCP) of feed mixtures and there was a significant regressive relationship between W-uCP (x) [g · kg - 1 DM] and D-uCP (y) [g · kg - 1 DM]: y = (0.94 ± 0.23)x + (18.78 ± 35.58), r 2 = 0.49, n = 19, p < 0.01. It was concluded that there exist significant associative effects of feed mixtures on uCP. In formulation of rations for ruminants the D-uCP should be used instead of W-uCP. Because of the low regression coefficient of the equation above, the D-uCP cannot be estimated from the W-uCP. [ABSTRACT FROM AUTHOR]

A mixture simplex design (special cubic version of Scheffe´’s canonical polynomial) was used to investigate associative effects of feed mixtures incubated using an in vitro gas production technique. The model included the principal effects (single feeds), double and multiple interaction (mixtures of two and three feeds). Two forage trees (Leucaena leucocephala and Lysiloma latisiliquum) were evaluated in two separate incubation batches. Commercial concentrate feed, grass hay and a fodder tree were used to prepare the mixtures in all possible combinations resulting from 0.0, 0.25, 0.50, 0.75 and 1.0 of grass, concentrate and one forage tree per batch. Pressure and gas volumes were monitored up to 168 h. After incubation the residues were used to measure DM and OM digestibility (in vitro dry matter (IVDMD) and in vitro organic matter (IVOMD)). Cumulative gas production (CGP (ml)) profiles were fitted to the equation CGP=a+b(1−e−kt). A significant associative response in total gas production (P<0.01) was found when the forage trees were mixed with the concentrate but not with the grass. Grass and concentrate mixtures increased gas production but the interaction was significant only in the L. latisiliquum batch (P<0.05). IVDMD and IVOMD were reduced by the inclusion of leucaena in the mixture (P<0.01). Rate of gas production, k (% h−1) was significantly depressed when L. latisiliquum was a component of the mixture (P<0.01) but not in all remaining mixtures, including those that contained leucaena. It was concluded that mixture simplex designs are useful tools to identify and study in vitro associative effects of feed mixtures. [Copyright &y& Elsevier]

Albizia lebbeck (siris) is a tropical, dry season, deciduous, multi-purpose tree. Field observations indicate that fallen leaf is eaten by livestock. In this study, fallen leaf was offered to cattle as a supplement to poor quality hay from native pasture. Voluntary intake of leaf comprised 15% of the total diet but caused a 52% increase (P<0.10) in intake of the native hay and a 67% increase (P<0.10) in digestible dry matter (DM) intake. During co-fermentation in vitro of fallen leaf of siris with angleton grass (Dichanthium aristatum), fibre digestion proceeded faster in mixtures than would be expected from results with component substrates. Most of this associative effect was not due to the contribution of N by siris leaf, but due to the cell wall matrix. The soluble extract from siris leaf obtained by sequential extraction with boiling ethanol and water, when added to grass caused an inhibition of grass digestion by a diverse rumen microbial inoculum, but stimulated digestion by Ruminococcus flavefaciens AR67 and microbial consortia originating from addax and kudu antelopes. Responses varied with microbial inoculum, the maximum increase in neutral detergent fibre (NDF) digestibility was 110 g/kg (P<0.05) 72 h after inoculation with addax consortia. Most of the activity was retained on ultrafiltration (<3000 MW cut off) or after dilute acid hydrolysis and was similar to that obtained with extracts of green pasture legumes and eucalyptus leaves. When the water soluble fraction of siris leaf was dosed into the rumen of sheep fed rhodes grass (Chloris gayana) fed ad libitum at a level corresponding to 20% leaf, there was a 20% increase (P<0.01) in voluntary grass intake, but in situ digestibility was not affected. A similar response was obtained with the soluble fraction from lucerne (Medicago sativa). Fallen leaf of siris has considerable feed value as a supplement to dry season grass. This may be due to both its N content and a low molecular weight constituent, as well as the differing morphology and chemistry of the lignocellulose substrates in siris leaf and grass. [Copyright &y& Elsevier]