Association of lameness with milk yield and lactation curves in Chios dairy ewes

The objective of the study was twofold: (i) to quantify the differences in daily milk yield (DMY) and total milk yield (TMY) between lame and non-lame dairy ewes and (ii) to determine the shape of lactation curves around the lameness incident. The overall study was a prospective study of lameness for the surveyed sheep population, with a nested study including the selection of matching controls for each lame ewe separately. Two intensively reared flocks of purebred Chios ewes and a total of 283 ewes were used. Data, including gait assessment and DMY records, were collected on a weekly basis during on-farm visits across the milking period. A general linear model was developed for the calculation of lactation curves of lame and non-lame ewes, whereas one-way ANOVA was used for the comparisons between lame ewes and their controls. Lameness incidence was 12·4 and 16·8% on Farms A and B, respectively. Average DMY in lame ewes was significantly lower (213·8 g, P < 0·001) compared with the rest of the flock, where DMY averaged 1·340 g. The highest DMY reduction in lame ewes was observed during the week 16 of the milking period (P < 0·001), whereas the reduction of DMY, for lame ewes, remained significant at P < 0·001 level from week 8 to week 28 of milking. Comparisons between lame and controls revealed that at the week of lameness diagnosis a significant DMY reduction (P ≤ 0·001) was observed in lame ewes (about 32·5%), which was maximised 1 week later (35·8%, P ≤ 0·001) and continued for several weeks after recovery, resulting in 19·3% lower TMY for lame ewes for the first 210 d of the milking period (P < 0·01). Moreover, at flock level, TMY for non-lame and lame ewes, as calculated by the general linear model, was 318·9 and 268·0 kg, respectively. The results of this study demonstrate evidence of significant financial losses in dairy sheep due to lameness which, however, need to be accurately estimated in further, more detailed, analyses.

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Selecting and Interpreting Inferential Statistics Selection of Inferential Statistics The General Linear Model Interpreting the Results of a Statistical Test

SPSS for Intermediate Statistics ◽

10.4324/9781410611420-7 ◽

2004 ◽

pp. 68-87

Keyword(s):

Linear Model ◽

General Linear Model ◽

Statistical Test ◽

General Linear ◽

Inferential Statistics ◽

Selection Of

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Factors affecting milk yield and ewe’s lactation curves estimated with test-day models

Czech Journal of Animal Science ◽

10.17221/3968-cjas ◽

2011 ◽

Vol 51 (No. 11) ◽

pp. 483-490 ◽

Cited By ~ 17

Author(s):

M. Oravcová ◽

M. Margetín ◽

D. Peškovičová ◽

J. Daňo ◽

M. Milerski ◽

...

Keyword(s):

Linear Model ◽

Litter Size ◽

Milk Yield ◽

Fixed Effects ◽

General Linear Model ◽

Yield Variability ◽

Factors Affecting ◽

Lactation Curve ◽

Daily Milk Yield ◽

Daily Milk

Test-day records of purebred Tsigai, Improved Valachian and Lacaune ewes were analysed with a general linear model in order to investigate the effects of flock-test day, lactation number, days in milk, litter size and month of lambing. In total, 121 576 (Tsigai), 247 902 (Improved Valachian) and 2 196 (Lacaune) test-day records gathered over the period 1995–2005 were included in the analyses. Average daily milk yields were 0.604 ± 0.279 kg (Tsigai), 0.595 ± 0.243 kg (Improved Valachian) and 1.053 ± 0.475 kg (Lacaune). The significant (P < 0.05) or highly significant (P < 0.01) effects of flock-test day, lactation number (except for Lacaune), days in milk, litter size (except for Lacaune) and month of lambing (either fixed effects or covariates) tested by Fisher’s tests were shown. The model explained about 50% of daily milk yield variability, with coefficients of determination as follows: 0.479 for Improved Valachian; 0.487 for Tsigai; 0.537 for Lacaune. Differences in estimated least-squares means were tested using multiple-range Scheffe’s tests. A lower daily milk yield was found for the first lactation, single litter and lactations starting in March in comparison with daily milk yield for the second and third lactations (except for Lacaune), multiple litter and lactations starting in January and February (except for Improved Valachian). Ali-Schaeffer regression adopted for sheep was used for the fitting of lactation curve according to breed.  

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