I live in Florida, where the heat settles in like an extra layer of clothing by late morning. Summers here are long, sticky, and relentless. And if I’m sweating, you can bet my goats are too. I’ve noticed it for years, when the mercury climbs, feed intake drops, weight gains slow, and pregnant does start looking a little too lean. This study, “Update of nutritional requirements of goats for growth and pregnant does in hot environments,” published in Animal speaks directly to the challenges of managing goat nutrition under thermal stress, and for those of us raising animals in hot or subtropical climates, it’s offers great insight.
The study focuses on updating metabolizable energy (ME)1the portion of gross energy in feed that is available to the animal after accounting for energy losses in feces, urine, and combustible gases (primarily methane). It’s a key metric for assessing the energy value of feed for ruminants, as it reflects the energy an animal can actually utilize for maintenance, growth, and production. and digestible protein (DP)2the portion of dietary protein that can be broken down and absorbed by your goat. requirements for two key groups: growing goats and pregnant does, specifically in hot conditions. Rather than relying on outdated tables that assume thermoneutral environments, the authors applied newer data and modeling tools to offer more precise estimates under heat stress. This shift reflects a broader recognition in livestock science that environmental heat isn’t just a discomfort; it’s a physiological disruptor that changes how energy is used and how nutrients are absorbed.
ME requirements for maintenance in growing goats increase as ambient temperatures rise. For instance, a goat exposed to 35°C requires roughly 12.5 percent more energy for maintenance than one kept at a cooler 25°C. This isn’t just a slight tweak to the diet. When intake is already down due to heat, that extra 12.5 percent represents a real nutritional challenge. Protein requirements climb too, though at a slightly lower rate. In other words, the hotter it gets, the more we need to concentrate nutrients in every bite the goat takes.
The researchers modeled growth under two environmental conditions: thermoneutral and heat-stressed. The simulations show that under hot conditions, goats with the same body weight and growth target need more ME and DP to maintain progress. This aligns with what many of us see in real life: goats that seem to plateau in growth during the hottest months unless their diets are adjusted. These figures are especially useful for small farms trying to predict growth rates and plan feed purchases accordingly.
Pregnancy introduces even more complexity. The study models how ME and DP demands escalate during late gestation. The final 30 days of pregnancy represent a period of steep nutritional demand, particularly when the doe is carrying twins or triplets. And under heat stress, those requirements are even higher. It becomes clear that pregnant does in hot climates are walking a nutritional tightrope. If we feed them as if they’re in cool weather, we’re likely underfeeding them. And underfeeding in late pregnancy doesn’t just affect the dam, it can influence kid birth weights, kidding ease, and early kid survival.
“It is well-established that a combination of hormonal effects and the pressure exerted by the pregnant uterus on the rumen leads to reduced feed intake capacity in pregnant females during the latter half of pregnancy. This typically occurs from around 76 days onwards in goats (Forbes, 2007). Paradoxically, during this period, the products of pregnancy experience an accelerated rate of protein and energy growth, as indicated by Härter et al. (2016). Therefore, these physiological changes are the main reason for the increase in kEp and kPp with the pregnancy progression.”
Myth Busting: This quote is important because it highlights why we need to feed our does in late pregnancy more and more often not, like I’ve seen on Facebook, less because it makes the babies too big.
Limitations
This study is solid, with a clear methodology and well-structured models. That said, it does rely heavily on simulations and prior literature rather than new field trials. The goats considered in the models are assumed to be healthy and managed in reasonably well-controlled systems. For those of us in pasture-based or mixed forage systems, especially with fluctuating forage quality or water access, real-world adjustments will still be necessary.
Relevance for Us
What does this mean for those of us sweating it out with our goats in Florida or other hot regions? It means we should treat summer not just as a season, but as a nutritional condition. If you’re feeding a standard ration all year long, odds are you’re underfeeding your animals during the hottest months, especially if they’re young and growing or entering late pregnancy. High-quality alfalfa, energy-dense grains, and supplemental protein sources like soybean meal or cottonseed can help close the gap. Feeding early in the morning or later in the evening can also increase intake. Monitoring body condition regularly and adjusting rations accordingly becomes even more important when temperature, humidity, and feed palatability all conspire to suppress appetite.
Quick Takeaways
Goats need more energy and protein when it’s hot, even though they tend to eat less.
Growth and pregnancy are both negatively impacted by heat stress unless rations are adjusted.
Environmental support, such as shade, airflow, cool water, is essential but not enough on its own.
Authors
The paper is authored by H.P. Silva, H.C. Fernandes, R.F. de Melo, A.T. Lima, and C.A. Souza Júnior. They are affiliated with agricultural science departments and veterinary programs in Brazil, which offers a comparable climate to much of the southern U.S. H.P. Silva and H.C. Fernandes are part of a broader body of work exploring animal nutrition and physiology under environmental stress. Their previous studies cover everything from digestibility under forage restriction to nutritional modeling in tropical livestock systems.
If you have Saanens, this one might be of interest: Medeiros AN, Resende KT, Teixeira IA, Araújo MJ, Yáñez EA, Ferreira AC. Energy requirements for maintenance and growth of male saanen goat kids. Asian-Australas J Anim Sci. 2014 Sep;27(9):1293-302.
Funding
The research was supported by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), a Brazilian federal agency that funds graduate-level education and academic research. CAPES support signals rigorous academic standards and a strong peer review process behind the study.
Citation
Silva, H.P., Fernandes, H.C., de Melo, R.F., Lima, A.T., & Souza Júnior, C.A. (2024). Update of nutritional requirements of goats for growth and pregnant does in hot environments. Animal. https://doi.org/10.1016/j.animal.2024.100150
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Footnotes
- 1the portion of gross energy in feed that is available to the animal after accounting for energy losses in feces, urine, and combustible gases (primarily methane). It’s a key metric for assessing the energy value of feed for ruminants, as it reflects the energy an animal can actually utilize for maintenance, growth, and production. ↩︎
- 2the portion of dietary protein that can be broken down and absorbed by your goat. ↩︎