Water is a nutrient of extreme importance for animals and must be considered vital in any rearing phase. The increasing scarcity of this precious natural resource has concerned different segments of society in order to find solutions for rational and sustainable use of this nutrient. Small ruminants, especially sheep and goats, have social and economic importance due to their great ability in adapting to adverse environmental conditions and using water efficiently. Thus, they might be a good alternative to mitigate the climate change effects and to generate foreign exchange and improving life condition in many places of the world. The concept of water productivity for livestock production is relatively new and there are few studies in the world, especially in Brazil. More researches and new technologies for water use in livestock production are indispensable.

The objective of this work was to evaluate the productive performance, biological efficiency, and the competitive ability of the forage cactus-sorghum intercropping under different irrigation depths with saline water in the Brazilian Semiarid Region. The experiment was carried out in Serra Talhada, in the state of Pernambuco, between 2014 and 2015, in a randomized complete block design, with four replicates, and a 5x3 factorial arrangement in split plots, with one year of forage cactus cycle and two years of sorghum cycles. The plots were composed by four irrigation water depths based on the fractions of 25, 50, 75, and 100% of the reference evapotranspiration, besides dry conditions; and the subplots consisted of three cropping systems (single crop of forage cactus, single crop of sorghum, and intercropping of forage cactus-sorghum). The increase of water irrigation depths increased the yields of sorghum in single crop and of the forage cactus-sorghum intercropping. The intercropping system promoted production stability with a higher system productivity index (SPI) for forage cactus-sorghum intercropping (6,279.02 kg ha^-1 DM) than for forage cactus in single crop (4,626.98 kg ha^-1 DM). The relative density coefficient (12.33) was indicative of the great compatibility of the intercropping system. The forage cactus-sorghum association shows biological advantage and competitiveness capacity, with a higher productive index than their monocultures.

O objetivo deste trabalho foi avaliar a composição botânica, a disponibilidade e a qualidade da forragem e da dieta de animais fistulados alimentados na Caatinga, no período chuvoso, em Pernambuco. Avaliaram-se a composição botânica e a disponibilidade de fitomassa dos estratos herbáceo, arbustivo e arbóreo, nos meses de março e junho. A avaliação da qualidade da forragem foi feita por meio da análise bromatológica, realizada em todos os meses do período chuvoso. Foram encontradas 67 espécies, das quais 28 herbáceas, 20 arbustivas e 19 arbóreas. Destas, 19 foram encontradas na dieta dos animais. A disponibilidade de fitomassa do componente herbáceo variou de 1.369 kg ha-1 de matéria seca (MS), em março, para 452 kg ha-1 de MS em junho. A disponibilidade do estrato arbustivo aproximou-se do herbáceo, enquanto o componente arbóreo contribuiu com apenas 178 kg ha-1 de MS. Apesar de a disponibilidade de fitomassa ser relativamente alta, apenas uma pequena porcentagem do material encontrado pode ser considerada como forragem. Foi observada baixa digestibilidade da proteína, provavelmente em conseqüência do alto teor em lignina.

This study evaluated the performance, body water balance, ingestive behavior and blood metabolites in goats fed with cactus pear silage subjected to an intermittent water supply. Thirty-six goats were distributed in a randomized block design arranged as a 3 × 3 factorial with cactus pear silage in the goats’ diet (on a 0%, 21% and 42% dry matter-DM basis) and water offer frequency (ad libitum, and 24 and 48 h water restrictions). There was an interaction only between the cactus pear silage level and water offerings for drinking water. Goats fed 42% cactus pear silage had greater intake of non-fibrous carbohydrates, energy, Ca, Mg and Na minerals, water intake, urinary water excretion, body water retention and nutrient digestibility. Cactus pear silage inclusion up to a 42% rate reduced eating and ruminating time and increased the time spent idling as well as the eating and the ruminating efficiency rate. Water restriction at 48 h reduced drinking water intake. Performance and blood metabolites were not affected by cactus silage inclusion or water offering. Cactus pear silage inclusion at up to 42% for goats is recommended during periods of water shortage in semiarid and arid regions because it improves eating, the ruminating efficiency rate, and body water retention; cactus pear silage inclusion at this rate reduces water consumption and it does not affect the performance or health of the animals.