Mapping quantitative trait loci (QTL) in sheep. IV. Analysis of lactation persistency and extended lactation traits in sheep

<p>Abstract</p> <p>Background</p> <p>In sheep dairy production, total lactation performance, and length of lactation of lactation are of economic significance. A more persistent lactation has been associated with improved udder health. An extended lactation is defined by a longer period of milkability. This study is the first investigation to examine the presence of quantitative trait loci (QTL) for extended lactation and lactation persistency in sheep.</p> <p>Methods</p> <p>An (Awassi × Merino) × Merino single-sire backcross family with 172 ewes was used to map QTL for lactation persistency and extended lactation traits on a framework map of 189 loci across all autosomes. The Wood model was fitted to data from multiple lactations to estimate parameters of ovine lactation curves, and these estimates were used to derive measures of lactation persistency and extended lactation traits of milk, protein, fat, lactose, useful yield, and somatic cell score. These derived traits were subjected to QTL analyses using maximum likelihood estimation and regression analysis.</p> <p>Results</p> <p>Overall, one highly significant (LOD > 3.0), four significant (2.0 < LOD < 3.0) and five suggestive (1.7 < LOD < 2.0) QTL were detected across all traits in common by both mapping methods. One additional suggestive QTL was identified using maximum likelihood estimation, and four suggestive (0.01 < P < 0.05) and two significant (P < 0.01) QTL using the regression approach only. All detected QTL had effect sizes in the range of 0.48 to 0.64 SD, corresponding to QTL heritabilities of 3.1 to 8.9%. The comparison of the detected QTL with results in cattle showed conserved linkage regions. Most of the QTL identified for lactation persistency and extended lactation did not coincide. This suggests that persistency and extended lactation for the same as well as different milk yield and component traits are not controlled by the same genes.</p> <p>Conclusion</p> <p>This study identified ten novel QTL for lactation persistency and extended lactation in sheep, but results suggest that lactation persistency and extended lactation do not have a major gene in common. These results provide a basis for further validation in extended families and other breeds as well as targeting regions for genome-wide association mapping using high-density SNP arrays.</p

The effect of pen design on pen floor cleanliness in farrowing pens for loose housed lactating sows

The aim of this study was to investigate the effects of design of farrowing pens for loose housed sows on dunging pattern and pen cleanliness. Thirty commercial pig herds in Norway were visited by a trained observer. Pens were divided into five sectors and the amount of dung in each sector (score 0 – 3), and the proportion of sector covered with dung, were scored. Pen cleanliness indices (PCI) were then calculated for a total of 317 pens, using two models. For Model B, the PCIB varied between herds from 1.2 in the herd with the cleanest pens to 10.4 in the herd with the dirtiest pens. However, variation within herds was also large. For the 5 herds with the lowest PCIB, the pens were on average larger, had a proportionally larger area of slatted floor, were provided with more bedding material and the pen side walls were solid.acceptedVersio

The effect of pen design on pen floor cleanliness in farrowing pens for loose housed lactating sows

The aim of this study was to investigate the effects of design of farrowing pens for loose housed sows on dunging pattern and pen cleanliness. Thirty commercial pig herds in Norway were visited by a trained observer. Pens were divided into five sectors and the amount of dung in each sector (score 0 – 3), and the proportion of sector covered with dung, were scored. Pen cleanliness indices (PCI) were then calculated for a total of 317 pens, using two models. For Model B, the PCIB varied between herds from 1.2 in the herd with the cleanest pens to 10.4 in the herd with the dirtiest pens. However, variation within herds was also large. For the 5 herds with the lowest PCIB, the pens were on average larger, had a proportionally larger area of slatted floor, were provided with more bedding material and the pen side walls were solid

The effects of global navigation satellite system (GNSS) collars on cattle ( Bos taurus) behaviour

The use of Global Navigation Satellite System (GNSS) collars has become an increasingly important research tool to study the behaviour of domestic livestock species in grazing conditions. However, relatively little is known about the effects on livestock behaviour of livestock “wearing” such collars. The aims of the present research were to determine if GNSS collars affect the behaviour of beef cattle at pasture, and whether an habituation period is required before the animal is accustomed to wearing the device. Behaviour observations were conducted on 20 Charolais cows which were maintained as a single herd in an 8.9 ha paddock. Behaviour was recorded during 13 of 15 days using a scan sampling technique every 5 min for a total of 8 h daily. The trial was divided into three, 5-d periods: before, with and after wearing GNSS collars. During the “with collar” period, 10 randomly selected cows were fitted with a GNSS collar (CD cows) weighing 0.61 kg (0.1% of liveweight) whereas the remaining 10 cows were not fitted with GNSS collars (NC cows). Over the course of the 15 days, 12 mutually exclusive behaviours were recorded for all cows: stand stationary, graze, walk, run, drink, stand ruminate, lie ruminate, rest/idle, social, self-directed, other and out of view. No significant behavioural differences were found between CD and NC cows, with the exception of stand stationary which was greater in CD (9.7%) than NC cows (7.3%). However, there was no interaction with Collar by Period, Day and Hour for any behaviours. During the first hour during the “with collar” period there was no significant effect on behaviour between CD and NC cows when behaviour:hour of day combinations were analysed. Therefore, it would appear that the presence of GNSS collars did not modify any cow behaviours with the exception of stand stationary over the course of this trial, and for future trials an habituation period to the collars is not necessary. This knowledge validates the use of GNSS technology for studying cattle grazing behaviour, and is thus important for future research involving the application of these remote sensing devices to study livestock behaviour

Appendix Table 2:

All cases of feline antebrachial fractures, includes configuration, complications, and final outcomes.</p

Appendix Table 1:

Owner response scores and their description.</p