Simple Summary: One of the common approaches to alleviating heat-stress in poultry is nutritional manipulation using herbal extracts or their derivatives to maintain the health, welfare, and performance of birds. The present study investigated the protective effect of boldo leaf extract against the harmful effects of cyclic heat stress in two broiler strains (Arbor Acres; AA and Avian-48; AV). Administration of boldo in drinking water was able to restore growth and health traits to nearly normal values. Generally, AA chicks were better able to withstand heat stress and were also more likely to utilize boldo extract than AV chicks. The use of boldo leaf extract in poultry production can assist in mitigating the effect of heat stress, improving the antioxidant defense system, and increasing productivity and profitability.Abstract: There is increasing interest in the use of natural antioxidant supplements in poultry diets as protection against the adverse effects of heat stress. The potential protective effect of boldo (Peumus boldus molina) leaf extract, which have antioxidant activity, were investigated against the harmful effects of heat stress in two broiler strains. Arbor Acres (AA) and Avian-48 (AV) chicks were divided into thermoneutral (TN) and heat stress (HS) groups and treated with 1 g boldo leaf extract/4 L drinking water during the heat stress period. HS reduced growth performance in both strains. The phagocytic index, phagocytic activity, and eosinophil and lymphocytes counts were significantly elevated in TN and HS AV birds but not altered in AA birds. Boldo extract treatment partially eliminated the previous negative impacts of heat stress. AA chicks were better able to withstand HS than AV chicks. Serum concentrations of total lipids and cholesterol were reduced in HS birds of both strains. Malondialdehyde, superoxide dismutase, and glutathione peroxidase levels were elevated but restored with the administration of boldo leaf extract in HS birds of both strains. Economic parameters were negatively affected by HS but restored to values close to those of the control group in boldo-treated HS birds. In conclusion, the administration of boldo leaf extract in drinking water was effective in neutralizing the harmful effects of heat stress on growth performance, blood indices, and economic parameters and improved the antioxidant defense system in heat-stressed birds.

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A total of 108 Holstein cows were used to evaluate the effect of drenching propylene glycol (PG) either individually or in combination with glycerol (G) on body condition score (BCS), production, reproductive performance, protection against subclinical ketosis and economic benefit of dairy cows during the transition period. The six groups (n = 18/group) were; Control group, cows received no treatment; PG300, cows were drenched 300 mL PG for 7 days pre-expected day of calving and 21 days post-calving; PG400, cows were drenched 400 mL PG for 7 days pre-and 7 days post-calving; PG500, cows were drenched 500 mL PG for 10 days pre-and 10 days post-calving; GPG150, cows were drenched a mixture of 150 mL G and 150 mL PG for 21 days pre-and 21 days post-calving; GPG250, cows were drenched a mixture of 250 mL G and 250 mL PG for 21 days pre-and 21 days post-calving. BCS at 30 days in milk (DIM) was significantly higher in all treated groups in comparison to the control one and the best values were observed in GPG250, GPG150 and PG500 groups. Lactation length (LL) was significantly (p < 0.001) shorter in GPG250, GPG150 and PG500 groups than control group. There was a significant increment in 305 milk yield (p < 0.001) and average daily milk yield (p < 0.001) in GPG250 and PG500 groups than other groups except for PG300 with the lowest values for control and PG400. Cows in all treatment groups were observed in heat and conceived earlier as well as had shorter open days and calving interval durations (p < 0.001) and low number of services per conception (p = 0.004) compared to control group with better results for PG500 and GPG250 groups. BHB level and percentage of cows suffered from subclinical ketosis at 7 DIM was significantly lower in GPG250, GPG150 and PG500 groups than control group. Cows in treatment groups had a significantly higher glucose level (p = 0.006) compared to control group. Regarding to economics, the control group showed the highest feed costs, insemination costs and total costs per animal. Additionally, control and PG400 groups had the highest cost per kilogram of milk from total and feed costs compared to other cows. PG300, PG500 and GPG250 groups recorded a greater net return and income over feed cost (IOFC). In conclusion, the continuous drenching of propylene glycol either individually or in combination with glycerol regimens for long duration (PG300, PG500, GPG150, GPG250) during the transition period of dairy cows may reduce the incidence of subclinical ketosis and consequently improve milk production, reproduction and economics compared to drenching for short duration (PG400).

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The present study investigated the effects of dietary supplementation of Saccharomyces cerevisiae (SC) on growth performance, carcass traits, blood biochemical parameters, histological changes in intestinal wall and economic indices in two breeds of weanling rabbits (V-Line and Rex). One-hundred and twenty weaned male rabbits were allotted randomly into four groups in factorial arrangement. The results could be summarized as follows: dietary supplementation of SC signifi cantly accelerated body weight gain (BWG), reduced feed conversion ratio (FCR) and increased profi t. The highest BWG and the lowest FCR were noticed in each breed when interacted with SC. There were non-signifi cant differences in carcass traits due to the studied factors, except in loin and dressing percentages. The highest percentages of loin and dressing were obtained from V-line when fed diet supplemented with SC. The treated rabbits with yeast were characterized by an increase in Brunner`s gland and villi. Dietary Supplementation of SC decreased blood total glycerides and cholesterol and increased blood total protein, albumin and A/G ratio. The treated group showed higher profi tability than the control.Conclusively, dietary supplementation of SC provided benefi cial effects in growth performance and profi tability of rabbits. Finally, dietary supplementation of SC is highly recommended in growing rabbits.