Analysis of water intake, dry matter intake and daily milk yield using different error covariance structures

Group housing for lactating sows with electronically controlled crates: 1. Reproductive traits, body condition, and feed intake

The aim was to compare a group housing system (GROUP) and a conventional single housing (SINGLE) for lactating sows with regard to the performance of sows and piglets. Data of 132 cross-breed sows were collected in 11 batches with 6 sows in GROUP and SINGLE in each batch. The GROUP had single pens (4.7 m(2)) with electronically controlled crates and a shared running area (13 m(2)). The sows in GROUP were retained in the crates 3 d prepartum until 1 d postpartum. Piglets were able to leave the single pens on d 5 postpartum. Recorded traits per litter included the number of piglets born alive and weaned, piglet losses, and individual BW at birth and weaning. In addition, body condition and back fat thickness before and after lactation (26 d) and the daily feed intake of the sows were measured. Gilts and sows were analyzed separately. The reproductive traits did not differ significantly (P > 0.05) between the farrowing systems with exception of the weaning weights (GROUP = 7.6 ± 0.12 kg vs. SINGLE = 8.1 ± 0.12 kg; P < 0.05). Group housed and SINGLE sows had 14.4 ± 0.47 and 14.6 ± 0.45 piglets born alive, respectively. In both housing systems, sows weaned 11.4 piglets (SEM = 0.14 and 0.13 for GROUP and SINGLE), respectively. Most piglet losses (72%) occurred during the first 3 d postpartum. At this point in time, piglets in GROUP and SINGLE were housed in single pens. In the single pens, GROUP sows could leave the farrowing crate whereas SINGLE sows were fixed in crates during the whole lactation. In total, piglet losses were not significantly different during lactation between GROUP and SINGLE treatments (2.2 ± 0.05 and 2.4 ± 0.05 piglets per litter, respectively). Sows housed in GROUP had a significantly lower (P < 0.05) BCS (2.2 ± 0.05) after lactation compared with SINGLE sows (BCS = 2.4 ± 0.05). This development could not be verified using the back fat thickness value at weaning (GROUP = 14.4 ± 0.25 mm vs. SINGLE = 14.6 ± 0.23 mm). Daily feed intake was significantly greater for GROUP sows (6.4 ± 0.08 kg per day) than SINGLE sows (6.15 ± 0.08 kg per day; P < 0.05). In conclusion, the performance of GROUP and SINGLE sows was similar with the exception of lighter weaning weights in GROUP housing.

Lucerne silage in high yielding dairy cows: effect of parity and analysis of reasons in mixed-parity group housing using random regression test-day models

A study with high-yielding dairy cows was re-analysed in order to test the suitability of lucerne silage separately for primi- and multiparous cows as an alternative to grass silage in maize-based total mixed rations (TMR). Lactation curves were fitted using random regression test-day models for energy corrected milk (ECM) and dry matter intake (DMI) as well as for number and duration of feeder visits (NFV and DFV, respectively). Existing models for ECM and DMI were extended by animal-specific random effects, which were formulated in their dependency on days in milk. For NFV and DFV random regression models were applied for the very first time. The chosen approach of statistical analysis permitted comparisons of the lactation curves as well as of least square means for sub-periods to answer nutritional questions. Whilst primiparous cows had generally lower DMI and ECM as compared to multiparous cows, only in primiparous cows a negative effect of lucerne TMR on ECM was observed, especially in early lactation. Nutritional factors should be rejected because of very similar ECM between the various TMR in multiparous cows. Traits of feeding behaviour indicated that particle size could contribute to the decreased ECM. Even more impact on the lower ECM should be addressed to domination behaviour of multiparous cows. The resulting restlessness of primiparous cows caused a reduced intake per minute spent at the feeder. Further studies should focus on optimising the proportion and chopping length of lucerne in the diet and to improve flock management to maximise feed intake of primiparous cows. Generally, statistical analysis of lactation data became a very complex issue. It seems inevitable that nutritionists and statisticians team up to address this problem.