Light (III): Proof of how to get levels right JOHN GADD


F


or the breeding sow and gilt, correct lighting levels are so important. Two decades ago water was the ‘forgotten nutri- ent’ – since rectified. I only wish that lighting the ‘forgotten management task’ was equally remedied.


My point is that many pig breeders just do not realise what degree of brightness is needed, and a light meter is a vital tool to make sure that there is enough – and occasionally too much. Here is the proof from several sources, highlighted in various tables. Table 1 shows overall throughput. Table 2 deals with the question how to reduce autumn infertility. Table 3 deals with the lighting of farrowing rooms to the latest standards for at least 16 hours per day, compared to extinguishing the main lights when staff vacate the room (50 lux). In this table, each litter had the same numbers. Two beneficial effects could be seen here. Rebreeding was smooth- er and either the sows let down more milk or the piglets consumed more. Last but not least, Tables 4a and 4b show figures of the effects of providing shade in bright spring and early summer weather. It shows before-and-after results from three farms. Shade levels about 50-80 lux compared to 360-420 lux outside, and tem- peratures some 3˚C lower. Two farms benefitted from early summer shading, one did not. American results on shading their outside runs seem to give similar or better results.


Summary • Much better awareness of correct levels of lighting is needed, even in modern pig buildings. • This cannot be done accurately enough without the regular use of a light meter. • Pig farmers do not realise how bright the light needs to be in the breeding barn and in the farrowing house. • Careful control of the lengths of light and dark periods seems to be essential. • Manipulating light levels is one method (out of many) of lessening the effect of both the autumn and late winter/spring variants of seasonal infertility. • Measuring light should be just in front of the sow’s eyes (common sense!) not anywhere in the building. • Control of light for outdoor sows is very difficult. • Control for sows indoors in groups and in outside runs is much easier.


References are available on request.


Table 1 – Infl uence of correct light levels on reproductive performance.


Days to mating Mated (0-5 days) Mated (6-10 days)


Control 5,9


68,50% 26,80%


Mated (more than 16 days) 4,60% Source: Petchey (1987)


Required light 5,5


83%


10,90% 6,00%


What the textbooks don’t tell you about…


Table 2 – Combatting daylight reduction from July-August to midwinter. Natural daylight


Abortions (range over short periods) Average stillbirths Gilts, regular returns


Empty days/ sow year (range) 5-12%


8% plus 17%


40-56 Source: Average of veterinary reports, Mid-West USA, 1990s.


Pens lit 4-6% 3% 6%


22-30


Table 3 – The effect of lighting farrowing rooms (50 lux). Control


At birth – litter weight (kg) At weaning – litter weight (kg) At rebreeding – regular returns (%) Weaning to successful mating (days) Source: Gadd, 2014.


16,8 16


11,3 6,1


Lights left on (400 lux) 77


81,9 8,7 5,6


Table 4A – The effect of providing shade in bright spring and early summer weather – Situation ‘before’, August/winter 2012.


Herd performances Farrowing rate (%)


Farm A Farm B Farm C 89


90 Days to successful service 6,1 5,7 87 5,9 Abortions and ‘no-shows’ 8% 9% 11%


Table 4B – The effect of providing shade in bright spring and early summer weather – Situation ‘after’, August/winter 2013.


Herd performances Farrowing rate (%)


Days to successful service


Farm A 96


5,1


Abortions and ‘no-shows’ 6% Source: John Gadd’s UK records (2014).


Well-known for his writing on pigs across 38 years, John Gadd has written over 2,600 articles and papers. His speciality is the cost- effectiveness of pig technology. Prior to becoming an inde- pendent writer and consultant, he had a long career in the British pig industry, from being stockman to chief pig advisor.


PIG PROGRESS VOLUME 32, No. 6, 2016 9


Farm B 89


5,8 9%


Farm C 92


5,4 8%


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