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"Animals Variation."
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Animal variation and classification
Explains how our animal classification system works and looks at how scientists use it to identify and group animal species, explores the variation between and within animal species and discusses how and why such variations have occurred.
Book
Genetic parameters of methane emissions determined using portable accumulation chambers in lambs and ewes grazing pasture and genetic correlations with emissions determined in respiration chambers1
Abstract
Methane (CH4) emission traits were previously found to be heritable and repeatable in sheep fed alfalfa pellets in respiration chambers (RC). More rapid screening methods are, however, required to increase genetic progress and to provide a cost-effective method to the farming industry for maintaining the generation of breeding values in the future. The objective of the current study was to determine CH4 and carbon dioxide (CO2) emissions using several 1-h portable accumulation chamber (PAC) measurements from lambs and again as ewes while grazing ryegrass-based pasture. Many animals with PAC measurements were also measured in RC while fed alfalfa pellets at 2.0 × maintenance metabolizable energy requirements (MEm). Heritability estimates from mixed models for CH4 and CO2 production (g/d) were 0.19 and 0.16, respectively, when measured using PAC with lambs; 0.20 and 0.27, respectively, when measured using PAC with ewes; and 0.23 and 0.34, respectively, when measured using RC with lambs. For measured gas traits, repeatabilities of measurements collected 14 d apart ranged from 0.33 to 0.55 for PAC (combined lambs and ewes) and were greater at 0.65 to 0.76 for the same traits measured using RC. Genetic correlations (rg) between PAC in lambs and ewes were 0.99 for CH4, 0.93 for CH4 + CO2, and 0.85 for CH4/(CH4 + CO2), suggesting that CH4 emissions in lambs and ewes are the same trait. Genetic correlations between PAC and RC measurements were lower, at 0.62 to 0.67 for CH4 and 0.41 to 0.42 for CH4 + CO2, likely reflecting different environmental conditions associated with the protocols used with the 2 measurement methods. The CH4/(CH4 + CO2) ratio was the most similar genetic trait measured using PAC (both lambs and ewes, 63% and 66% selection efficiency, respectively) compared with CH4 yield (g/kg DMI) measured using RC. These results suggest that PAC measurements have considerable value as a rapid low-cost method to estimate breeding values for CH4 emissions in sheep.
Journal Article
Rumen metabolic environment of dairy cows varying in susceptibility of subacute ruminal acidosis modifies in vitro bacterial composition and fermentation
The rumen metabolic environment from either SARA susceptible (S) or unsusceptible (U) cows, was hypothesized to alter the fermentative capacity and bacterial community composition. This was evaluated in vitro through exposure for a period of 24 h of the microbial inoculum of three donor cows to sterile ruminal supernatant obtained from a subset of 15 out of a group of 38 early lactating dairy cows which were either SARA S (
n
= 8) or U (
n
= 7) cows at pH 5.8 and 6.8. Compared to exposure to sterile supernatant from S cows, microbiota exposed to sterile supernatant from U cows produced more total volatile fatty acids, irrespective of the in vitro pH (6.8 or 5.8). Specifically, branched-chain volatile fatty acids (BCVFA), such as isobutyrate and total BCVFA are elevated/tended to be elevated in incubations with the sterile supernatant from U cows. Net lactate accumulation in incubations with U cows’ supernatant at pH 6.8 was higher than with S cows’ supernatant. Nevertheless, a lower relative abundance of
Firmicutes
, uncultured
Ruminococcaceae
,
Lachnospiraceae_UCG-008
, and
Anaerovoracaceae Mogibacterium
, as well as a higher relative abundance of
Prevotella
was observed after incubation with sterile supernatant from SARA S cows as compared with SARA U cows.
Journal Article
Geographic variation in behavior
Studies of animal behavior often assume that all members of a species exhibit the same behavior.Geographic Variation in Behavior shows that, on the contrary, there is substantional variation within species across a wide range of taxa.
eBook
An uncommon anatomic variation of the sartorius muscle in a domestic dog (Canis lupus familiaris)
The sartorius muscle is located in the pelvic limb of the dog and is divided into a cranial and caudal part. There is no report describing of the three parts of the sartorius muscle. The aim of the present report was to describe the presence of a third part of the sartorius muscle in a dog. Although it does not represent a malformation, it is an important anatomical variation to consider for didactic purposes of dissection and in surgeries of the pelvic limb, as in this case there is a need to move the muscles apart to maintain their integrity. Furthermore, this anatomical description is relevant for comparative purposes in this animal species.
Journal Article
Cerebellar plasticity and motor learning deficits in a copy-number variation mouse model of autism
A common feature of autism spectrum disorder (ASD) is the impairment of motor control and learning, occurring in a majority of children with autism, consistent with perturbation in cerebellar function. Here we report alterations in motor behaviour and cerebellar synaptic plasticity in a mouse model (patDp/+) for the human 15q11-13 duplication, one of the most frequently observed genetic aberrations in autism. These mice show ASD-resembling social behaviour deficits. We find that in patDp/+ mice delay eyeblink conditioning—a form of cerebellum-dependent motor learning—is impaired, and observe deregulation of a putative cellular mechanism for motor learning, long-term depression (LTD) at parallel fibre-Purkinje cell synapses. Moreover, developmental elimination of surplus climbing fibres—a model for activity-dependent synaptic pruning—is impaired. These findings point to deficits in synaptic plasticity and pruning as potential causes for motor problems and abnormal circuit development in autism.
Impairments of cerebellar-dependent motor control and learning are implicated in some forms of autism spectrum disorder (ASD). In this study, the authors provide a characterization of the motor deficits and cerebellar function abnormalities in a transgenic mouse model of ASD.
Journal Article
Susceptibility of dairy cows to subacute ruminal acidosis is reflected in both prepartum and postpartum bacteria as well as odd- and branched-chain fatty acids in feces
Background
The transition period is a challenging period for high-producing dairy cattle. Cows in early lactation are considered as a group at risk of subacute ruminal acidosis (SARA). Variability in SARA susceptibility in early lactation is hypothesized to be reflected in fecal characteristics such as fecal pH, dry matter content, volatile and odd- and branched-chain fatty acids (VFA and OBCFA, respectively), as well as fecal microbiota. This was investigated with 38 periparturient dairy cows, which were classified into four groups differing in median and mean time of reticular pH below 6 as well as area under the curve of pH below 6. Furthermore, we investigated whether fecal differences were already obvious during a period prior to the SARA risk (prepartum).
Results
Variation in reticular pH during a 3-week postpartum period was not associated with differences in fecal pH and VFA concentration. In the postpartum period, the copy number of fecal bacteria and methanogens of unsusceptible (UN) cows was higher than moderately susceptible (MS) or susceptible (SU) cows, while the genera
Ruminococcus
and
Prevotellacea_UCG-001
were proportionally less abundant in UN compared with SU cows. Nevertheless, only a minor reduction was observed in iso-BCFA proportions in fecal fatty acids of SU cows, particularly iso-C15:0 and iso-C16:0, compared with UN cows. Consistent with the bacterial changes postpartum, the lower abundance of
Ruminococcus
was already observed in the prepartum fecal bacterial communities of UN cows, whereas
Lachnospiraceae_UCG-001
was increased
.
Nevertheless, no differences were observed in the prepartum fecal VFA or OBCFA profiles among the groups. Prepartum fecal bacterial communities of cows were clustered into two distinct clusters with 70% of the SU cows belonging to cluster 1, in which they represented 60% of the animals.
Conclusions
Inter-animal variation in postpartum SARA susceptibility was reflected in post- and prepartum fecal bacterial communities. Differences in prepartum fecal bacterial communities could alert for susceptibility to develop SARA postpartum. Our results generated knowledge on the association between fecal bacteria and SARA development which could be further explored in a prevention strategy.
Graphical abstract
Journal Article