Think you can’t take the heat? At least you’re not a chicken

Weather affects all forms of agriculture, from the raising of animals to the growing of crops.

When a heat wave swept across San Luis Obispo County in June 1990 with higher-than-normal humidity levels, the Cal Poly Poultry Science Unit — which sells wonderful eggs throughout San Luis Obispo and northern Santa Barbara counties — lost birds due to heat stress.

When temperatures rise above the 90s, chickens are subject to overheating. They can’t sweat like humans to keep themselves cool. Instead, they pant. According to Cal Poly’s eminent poultry authority, professor Robert Spiller, chickens have a series of thin-membrane air sacs in their body cavity.

These air sacs are lined with water. As a chicken pants with its beak wide open, the water inside these air sacs evaporates and cools the bird. But when the humidity levels are too high, this type of cooling doesn’t work very well.

If the air is saturated with water vapor, it can’t hold any additional water. So, when the humidity level is high, less water in these air sacs can evaporate and the chickens just can’t cool as effectively.

The weather affects egg production as well. The optimum temperature for laying eggs is between 72 and 82 degrees Fahrenheit. If the temperature drops below 72 degrees, chickens will consume more feed to produce the same amount of eggs. This is because of the need to burn more calories to keep warm. If the temperature rises above 82 degrees, the hens will begin to pant. Panting consumes a lot of calories and the hens will produce less egg weight per pound of feed. On average, it takes about 3.5 pounds of feed to produce a dozen eggs.

The amount of sunlight also plays an important part in egg production. Here on the Central Coast, our shortest day has about nine hours and 47 minutes of sunlight on the first day of winter, while our longest day in June has about 14 hours and 31 minutes of sunlight during the summer solstice. As the days get shorter during the fall, egg production drops off. To keep egg production at a constant level, especially during the high-demand months of November through January, egg farmers supply about 16 hours of artificial light a day.

Steve Soderstrom, the Cal Poly Poultry Unit manager, told me it doesn’t take a very bright light to keep the chickens laying eggs. If the light is bright enough to read a newspaper, that’s enough light to keep the chickens happy.

Professor Spiller wanted to tell everyone that hormones were banned from poultry farming in the United States in the 1960s and are no longer used today.

Today’s weather

This October has produced very interesting weather, with rain during the first part of the month followed by a short heat wave and high waves along the beaches last week.

This upcoming week is appearing to be rather unremarkable.

The marine low clouds with area of drizzle will fill in over the majority of the coastal zones this morning and persist through late this morning. The marine layer should burn off by the afternoon hours from most locations.

Today’s temperatures will range from the low to mid-70s along the southwesterly facing beaches (Cayucos, Avila Beach and Shell Beach). The westerly facing beaches (Pismo Beach and Oceano) will be a little cooler, ranging from the high 60s to the low 70s, while the northwesterly facing beaches (Cambria, Morro Bay, Los Osos, Montaña De Oro and Nipomo Mesa) will range from the low to mid-60s.

The coastal valleys (San Luis Obispo) will reach the mid-70s, while the North County (Paso Robles is expected to hit the low 80s.

After a dry and warm Monday, marine clouds will increase again Tuesday into Wednesday, with increasing northwesterly (onshore) winds and cooler temperatures.

The remainder of the forecast period looks fair and dry, with temperatures near normal for mid-to-late October.

Today’s surf report:

A 2- to 3-foot northwesterly (290-degree deep-water) swell (with an 8- to 11-second period) will continue at this height and period through Monday morning.

Increasing northwesterly winds will generate a 2- to 4-foot northwesterly (310-degree deep-water) sea and swell (with a 4- to 11-second period) Monday afternoon through Tuesday morning. This northwesterly (310-degree deep-water) sea and swell will further build to 3 to 5 feet (with a 5- to 11-second period) on Tuesday afternoon and remain at this height and period through Friday.

Seawater temperatures will range between 57 and 59 degrees through Monday. Seawater temperatures are forecast to decrease to 56 to 58 degrees Tuesday and remain at this level through Friday.

Conservation tip

Installing solar power? To learn more, please visit www.pge.com and click the “Save Energy and Money” tab.

John Lindsey is a media relations representative for PG&E. He is also a local weather expert and has lived along the Central Coast for nearly 25 years. To subscribe to his daily weather forecast or ask him a question, email pgeweather@pge.com.