Sheep grazing causes shift in sex ratio and cohort structure of Brandt's vole: Implication of their adaptation to food shortage

Livestock grazing has been demonstrated to affect the population abundance of small rodents in grasslands, but the causative mechanism of grazing on demographic parameters, particularly the age structure and sex ratio, is rarely investigated. In this study, we examined the effects of sheep grazing on the cohort structure and sex ratio of Brandt's vole (Lasiopodomys brandtii) in Inner Mongolia of China by using large manipulative experimental enclosures during 2010–2013. Our results indicated that sheep grazing significantly decreased the proportion of the spring‐born cohort, but increased the proportion of the summer‐born cohort. Grazing increased the proportion of males in both spring and summer cohorts. In addition, we found a negative relation between population density and the proportion of the overwinter cohort. Our results suggest that a shift in the cohort structure and the sex ratio may be an important strategy for small rodents to adapt to changes in food resources resulting from livestock grazing.     

Birth of puppies of predetermined sex after artificial insemination with a low number of sex‐sorted,frozen–thawed spermatozoa in field conditions

The aim of this study was to evaluate fertility and sex ratios after artificial insemination in dogs under field conditions. Semen was cryopreserved as unsorted (control) or was separated into X‐ and Y‐chromosome‐bearing sperm using a cell sorter. Sixty female dogs were inseminated with frozen–thawed spermatozoa of 100 × 10⁶ unsorted (a dose in practice) and 4 × 10⁶ sorted (X and Y group, respectively). A total of 20 dogs became pregnant and 126 puppies were born from the three groups. The percentage of parturition was similar for the X (5/20; 25.0%) and Y (4/20; 20.0%) group (P > 0.05), but lower than controls (11/20; 55.0%) (P < 0.05). Ultimately 28 out of the 32 puppies produced from X group were female (87.5%) and 19/22 (86.4%) puppies of Y group were male. In contrast, sex ratio (51.4% to 48.6%) in the control was significantly different from the X, Y group (P < 0.05). However, male and female puppies in the control had similar birth weights and weaning weights to those from the X and Y groups. This preliminary information indicated that normal puppies of predicted sex can be produced with low numbers of sorted cryopreserved dog spermatozoa at a farm level, making sperm‐sexing technology potentially applicable for elite breeding units.     

Effect of the strain combination of the donor and recipient on the production efficiency of W‐bearing sperm in mixed‐sex germline chimeric chickens

Effect of the strain combination of the donor and recipient on production efficiency of W‐bearing sperm in mixed‐sex chimeric testes was analyzed. The combinations of the donors and recipients were White Leghorn (WL) and Rhode Island Red (RIR), and vice versa. Generated mixed‐sex chimeras that had the male phenotype at sexual maturity were classified into four groups: (1) a female WL donor and a male RIR recipient; (2) a male WL donor and a female RIR recipient; (3) a female RIR donor and a male WL recipient; (4) a male RIR donor and a female WL recipient. The mean number of W‐bearing sperm detected by in situ hybridization among 10 000 sperm observed were 147, 165, 30 and 45 in groups 1, 2, 3 and 4, respectively. The numbers in groups 1 and 2 were both significantly higher than those of groups 3 and 4 (P < 0.05). The combination of a WL donor and a RIR recipient produced W‐bearing sperm more efficiently than the reverse combination.     

Effects of concentrate‐to‐forage ratios and 2‐methylbutyrate supplementation on ruminal fermentation,bacteria abundance and urinary excretion of purine derivatives in Chinese Simmental steers

This study evaluated the effects of dietary concentrate levels and 2‐methylbutyrate (2MB ) supplementation on performance, ruminal fermentation, bacteria abundance, microbial enzyme activity and urinary excretion of purine derivatives (PD ) in steers. Eight ruminally cannulated Simmental steers (12 months of age; 389 ± 3.7 kg of body weight) were used in a replicated 4 × 4 Latin square design with a 2 × 2 factorial arrangement. Moderate‐concentrate (400 g/kg diet [MC ]) or high‐concentrate (600 g/kg diet [HC ]) diets were fed with or without 2MB (0 g/day [2MB ?] or 15.0 g/day [2MB +]). Dry matter intake and average daily gain increased, but feed conversion ratio decreased with the HC diet or 2MB supplementation. Ruminal pH decreased, but total volatile fatty acid increased with the HC diet or 2MB supplementation. Molar proportion of acetate and acetate‐to‐propionate ratio decreased with the HC diet, but increased with 2MB supplementation. Propionate molar proportion and ruminal NH ₃‐N content increased with the HC diet, but decreased with 2MB supplementation. Neutral detergent fibre degradability decreased with the HC diet, but increased with 2MB supplementation. Crude protein degradability increased with the HC diet or 2MB supplementation. Abundance of Ruminococcus albus , Ruminococcus flavefaciens , Fibrobacter succinogenes and Bufyrivibrio fibrisolvens as well as activities of carboxymethyl cellulase, cellobiase, xylanase and pectinase decreased with the HC diet, but increased with 2MB supplementation. However, abundance of Prevotella ruminicola and Ruminobacter amylophilus as well as activities of α‐amylase and protease increased with the HC diet or 2MB supplementation. Total PD excretion also increased with the HC diet or 2MB supplementation. The results suggested that growth performance, ruminal fermentation, CP degradability and total PD excretion increased with increasing dietary concentrate level from 40% to 60% or 2MB supplementation. The observed diet × 2MB interaction indicated that supplementation of 2MB was more efficacious for improving growth performance, ruminal fermentation and total PD excretion with promoted ruminal bacteria abundance and enzyme activity in the MC diet than in the HC diet.     

Predation by carpet pythons (Morelia spilota) is an important cause of mortality in a free‐living koala (Phascolarctos cinereus) population in South East Queensland

Koalas (Phascolarctos cinereus) are experiencing significant declines across the northern part of their range. However, unbiased, population‐level estimates of mortality are rarely reported, as it's difficult to quantify causes of mortality robustly in this cryptic species. We aimed to determine the relative importance of carpet python (Morelia spilota) predation in a free‐living koala population and describe the characteristic pathological findings during necropsy. In total, 503 koalas were captured, underwent veterinary examination and telemetric tagging, and were monitored after release over a four‐year period. Mortalities were detected when activity data reported by K‐Tracker® biotelemetry collars indicated low or zero activity, or during routine field monitoring events. Experienced koala veterinarians performed thorough, standardised necropsy examinations on retrieved carcasses to determine causes of death. The three, sometimes subtle, cardinal signs used to definitively diagnose carpet python‐caused deaths of koalas were a U‐shaped primary bite site, slicking of the fur by python saliva (particularly around the face), and diffuse, uniform pulmonary congestion. We found that carpet pythons were important predators of koalas, second only to wild dogs (dingoes and dingo hybrids (Canis familiaris dingo)), accounting for 11.6% of predation deaths and 7.2% of total deaths. Less than half (38%) of the koalas killed by carpet pythons were ingested. Though carpet pythons are known predators of koalas, their relative importance as a cause of mortality hasn't previously been recognised. Population viability analyses and conservation management plans benefit from robust cause‐of‐death data collected during longitudinal monitoring studies, requiring telemetry methods that facilitate rapid detection of mortalities.     

Evaluation of habitat requirements of small rodents and effectiveness of an ecologically‐based management in a hantavirus‐endemic natural protected area in Argentina

Hantavirus pulmonary syndrome is a severe cardio pulmonary disease transmitted to humans by sylvan rodents found in natural and rural environments. Disease transmission is closely linked to the ecology of animal reservoirs and abiotic factors such as habitat characteristics, season or climatic conditions. The main goals of this research were: to determine the biotic and abiotic factors affecting richness and abundance of rodent species at different spatial scales, to evaluate different methodologies for studying population of small rodents, and to describe and analyze an ecologically‐based rodent management experience in a highly touristic area. A 4‐year study of small rodent ecology was conducted between April 2007 and August 2011 in the most relevant habitats of El Palmar National Park, Argentina. Management involved a wide range of control and prevention measures, including poisoning, culling and habitat modification. A total of 172 individuals of 5 species were captured with a trapping effort of 13 860 traps‐nights (1.24 individuals/100 traps‐nights). Five rodent species were captured, including 2 hantavirus‐host species, Oligoryzomys nigripes and Akodon azarae. Oligoryzomys nigripes, host of a hantavirus that is pathogenic in humans, was the most abundant species and the only one found in all the studied habitats. Our results are inconsistent with the dilution effect hypothesis. The present study demonstrates that sylvan rodent species, including the hantavirus‐host species, have distinct local habitat selection and temporal variation patterns in abundance, which may influence the risk of human exposure to hantavirus and may have practical implications for disease transmission as well as for reservoir management.     

Effects of segregation and impact of specific feeding behaviour and additional fruit on voluntary nutrient and energy intake in yellow‐shouldered amazons (Amazona barbadensis) when fed a multi‐component seed diet ad libitum

Parrots are commonly fed multi‐component seed diets; however, both segregation and feeding behaviour might alter ingredient and nutrient composition of the offered diet. First, the nutritional impact of segregation was assessed as it occurs when multi‐component diets are temporarily stored in food containers that are replenished before completely emptied and birds being fed from the upper layer. The most detrimental effect hereof was a vast decrease in mineral supplements, leading to a decrease in Ca:P ratio in the offered food in relation to the formulated diet. Next, caloric distribution shifted towards more EE energy at the expense of NFE energy, as proportion of oilseeds increased and NFE‐rich seeds decreased. Next, a feeding trial was performed on six yellow‐shouldered amazons (Amazona Barbadensis) in which nutritional impact of parrot‐specific feeding behaviour was assessed as well as the influence of additional provision of fruit next to the seed mixture. Profound selective feeding behaviour and dehusking of seeds resulted in a vast increase in energetic density by up to 64% in the ingested fraction in relation to the offered mixture in toto. Furthermore, the already suboptimal Ca:P ratio further deteriorated and caloric distribution shifted by over twofold towards EE energy accompanied with a vast decline in NFE energy, CP energy remaining similar. Finally, provision of fruit next to the seed diet significantly lowered voluntary energy intake from 936 ± 71 to 809 ± 109 kJ ME/kg^0.75/day, without compromising adequate protein intake. In conclusion, notwithstanding efforts of nutritionists to formulate diets to approximate estimated, species‐specific requirements, nutritional composition of the actually consumed fraction of multi‐component seed diets can be vastly deteriorated by both animal and management factors. Furthermore, offering of fruit next to a seed‐based diet effectively reduces voluntary energy intake and can hence be applied to abate obesity.     

Methyl donors dietary supplementation to gestating sows diet improves the growth rate of offspring and is associating with changes in expression and DNA methylation of insulin‐like growth factor‐1 gene

The study aimed to investigate the effects of maternal dietary methyl donors on the performance of sows and their offspring, and the associated hepatic insulin‐like growth factor‐1 (IGF‐1) expression of the offspring. A total of 24 multiparous sows were randomly fed the control (CON) or the CON diet supplemented with methyl donors (MD) at 3 g/kg betaine, 15 mg/kg folic acid, 400 mg/kg choline and 150 μg/kg VB₁₂, from mating until delivery. After farrowing, sows were fed a common lactation diet through a 28‐days lactation period and six litters per treatment were selected to be fed until at approximately 110 kg BW. Maternal MD supplementation resulted in greater birthweight (p < 0.05) and increased the piglet weights (p < 0.01) and litter weights (p < 0.05) at the age of day 28, compared with that in CON group. The offspring pigs in the MD group had greater ADG (p < 0.05) and tended to lower F:G ratio (p = 0.07) compared with that of CON group from day 28 to 180 of age. The offspring pigs from MD group had greater serum IGF‐1 concentrations and expressions of hepatic IGF‐1 gene and muscular IGF‐1 receptor (IGF‐1r) protein at birth (p < 0.05), and greater hepatic IGF‐1 protein (p = 0.03) and muscular IGF‐1r gene expressions (p < 0.05) at slaughter, than that from the CON group. Moreover, the methylation at the promoter of IGF‐1 gene in the liver of newborn piglets and finishing pigs was greater in the MD group than that of the CON group (p < 0.05). In conclusion, maternal MD supplementation throughout gestation could enhance the birthweight and postnatal growth rate of offspring, associated with an increased expression of the IGF‐1 gene and IGF‐1r, as well as the altered DNA methylation of IGF‐1 gene promotor.     

Effects of graded levels of liquid brewer's yeast on chemical composition and fermentation quality in cassava pulp and rice straw‐based total mixed ration silage

This study aimed to evaluate the effect of liquid brewer's yeast (LBY) addition on chemical composition and fermentation quality of mixture of LBY and cassava pulp (CVP) with rice straw (RS) in different ratios during preservation periods. Four mixtures of LBY, CVP and RS were made, that is mixture ratio of LBY : CVP : RS of 0% LBY, 20% LBY, 35% LBY and 50% LBY were 0:70:30, 20:50:30, 35:35:30 and 50:20:30 as fresh matter, respectively. The bags were opened at weeks 0, 1, 2, 4 and 8 after storage. The contents of dry matter, organic matter, crude protein (CP), ether extract (EE), neutral detergent fiber and acid detergent fiber ranged 36.4‐40.0, 88.9‐90.8, 4.0‐12.0, 1.1‐1.3, 58.8‐61.6 and 37.6‐40.0, respectively, and the contents of CP and EE increased and the other components decreased in proportion to LBY inclusion (P < 0.01). 50% LBY had the highest (P < 0.05) pH (4.81) and ammonia nitrogen per total nitrogen (NH₃‐N/TN) (7.40%) and the lowest V‐score (90.3). Propionic and butyric acid contents were 0.01% or lower in each mixture and storage period. There were rapid pH decrease and NH₃‐N/TN increase during the first week of the storage period. The increases of NH₃‐N/TN and acetic acid content and decreases of pH, lactic acid content and V‐score during the preservation were more drastic as LBY inclusion increased. Although higher proportion of LBY produced higher CP and lower fiber contents in the mixture, attention should be paid for the reduction of fermentation quality during longer storage periods.     

Medium‐chain triglyceride as an alternative of in‐feed colistin sulfate to improve growth performance and intestinal microbial environment in newly weaned pigs

Five hundred and twenty‐eight newly weaned pigs were given four treatments, with eight replicates per treatment. Sixteen to 18 pigs were assigned per replicate and were fed diets supplemented with 0 or 3% medium‐chain triglyceride (MCT) and 0 or 40 ppm colistin sulfate (CS) in a 2 × 2 factorial arrangement for 2 weeks. The results showed that dietary supplementation with MCT improved the gain‐to‐feed ratio during days 3‐7 and in the overall period (P < 0.05). Dietary supplementation with MCT decreased coliforms counts (C) in colon and rectum content (P < 0.05). Dietary supplementation with CS decreased C and lactic acid bacteria plus C counts (L + C) in cecum (P < 0.05), and C, L + C (P < 0.01) and ratio of L and C (P < 0.05) in colon and rectum contents. The lack of interactions between MCT and CS indicates different modes of action and additive effects between the two supplementations. In conclusion, supplementation with MCT in diet with or without CS could improve the intestinal microbial environment and the feed utilization efficiency of newly weaned pigs.     

Effects of yeast culture supplementation and the ratio of non‐structural carbohydrate to fat on growth performance,carcass traits and the fatty acid profile of the longissimus dorsi muscle in lambs

The effects of yeast culture (YC) supplementation and the dietary ratio of non‐structural carbohydrate to fat (NSCFR) on growth performance, carcass traits and fatty acid profile of the longissimus dorsi (LD) muscle in lambs were determined in a 2 × 3 full factorial experiment. Thirty‐six Small‐tailed Han lambs were randomly divided into six groups with six replicates per group. The lambs were fed one of the six pelleted total mixed rations (TMRs) for 60 days after 15 adaption days. The six rations were formed by two NSCFRs (11.37 and 4.57) and three YC supplementation levels (0, 0.8 and 2.3 g/kg dietary dry matter). The average daily gain (ADG), dry matter intake (DMI) and feed conversion ratio (FCR) data of each lamb were recorded and calculated. All the lambs were slaughtered for determining carcass traits and fatty acid profile of the LD muscle. DMI was significantly increased (p < 0.05) in a quadratic fashion with 0.8 g/kg of YC supplementation. Carcass weight (CW) and dressing percentage (DP) were significantly increased (p < 0.05) in a linear fashion with 2.3 g/kg of YC supplementation. Animals fed with high‐NSCFR diet had higher (p < 0.05) contents of myristoleic acid (C14:1), pentadecanoic acid (C15:0) and cis‐10‐heptadecenoic acid (C17:1), and lower (p < 0.05) stearic acid (C18:0) content in LD muscle than those fed with low‐NSCFR diet. Moreover, ADG, growth rate (GR), backfat thickness (BFT), percentages of crude fat (CF) and crude protein (CP), SFAs, MUFAs and PUFAs in LD muscle, were significantly affected (p < 0.05) by interaction of dietary NSCFR and supplemental YC level. Overall, YC not only improved the growth performance and carcass traits of the animals but also modified the fatty acid profile of the LD muscle. Furthermore, the effects of YC supplementation may depend on dietary compositions.