Additional dietary calcium fed to Barred Plymouth Rock roosters reduces blood cholesterol, elevates seminal calcium, and enhances sperm motility, thermo-tolerance and cryosurvivability

Research Note: The effect of crude protein and calcium intake on fertility of male broiler breeders

This experiment investigated the effect of excess crude protein and/or calcium on male broiler breeder fertility. Forty-eight broiler breeder males, from a group of 60 that consistently produced a semen sample were allocated to one of 4 dietary treatments, formulated to provide either the male or female recommendation for crude protein and calcium, or their combinations. Birds were provided a constant daily feed allocation. Semen samples were collected and assessed for concentration and sperm mobility index. Commercial laying hens were also inseminated and the points of sperm hydrolysis counted in the membranes of the eggs produced after insemination. Dietary crude protein had no significant effect on sperm concentration at any age, but significantly poorer sperm concentration was seen in the males fed high calcium at 42 and 57 wk of age, and a significant interaction was observed at 60 wk of age, with the poorest sperm concentration from birds fed high crude protein and high calcium. There was no significant effect at any age of crude protein or calcium on sperm mobility index. The birds fed levels of crude protein and calcium recommended for males had significantly more points of sperm hydrolysis at 40 wk of age compared to all other dietary treatments, which indicates better fertilizing potential. While there were a few incidences of birds fed a ration with levels of crude protein and calcium recommended for males showing superior sperm quality, this was not a consistent trend across all ages or measures of fertility. Therefore, males fed a female ration at the correct allocation to ensure adherence to the bodyweight curve should not exhibit reduced (or improved) fertility, however, there were instances where birds fed the male recommended concentration of CP and Ca had improved measures of sperm quality.

Effects of monobutyrin supplementation on egg production, biochemical indexes, and gut microbiota of broiler breeders

The objective of the present study was to determine the effect of monobutyrin supplementation on egg production, biochemical indexes, and gut microbiota of broiler breeders at the late stage of production. A total of 180 healthy Qingyuan partridge broilers were randomly assigned to 2 groups: 1) corn-soybean meal-based diet and 2) basal diet supplemented with 250 mg monobutyrin/kg. Each treatment group had 6 replicates/cages with 15 birds within each replicate. The experiment started at week 33 and lasted for 8 wk. Egg production rate, feed conversion rate, shell breaking strength, and shell thickness were not different between control and treatment groups. Supplementation of monobutyrin increased egg weight and tended to decrease egg breaking rate of Qingyuan partridge chickens. Supplementation of monobutyrin did not affect any of the biochemical indexes except total protein concentration. The 4 antioxidant parameters measured were not affected either. Alpha diversity indexes (Shannon, Simpson, Chao1, Ace, and Good's Coverage) and composition of cecal microbiota were not affected by monobutyrin supplementation. Overall, supplementation of monobutyrin at 250 mg/kg level improved egg quality, but its effect on cecal microbiota composition was limited.

Effects of supplementation level and feeding schedule of butyrate glycerides on the growth performance and carcass composition of broiler chickens

Mixed mono- and tributyrate glycerides have been used for effective delivery of butyrate to the gut to benefit broilers. However, limited information is available on the efficacy of butyrate glycerides individually and in combination with different levels and feeding schedules. The present study has first investigated the effects of monobutyrin at inclusion levels of zero, 500, 1,000, 2,000, and 3,000 ppm on the performance of broilers, and second, the effects of its combination with tributyrin. In the monobutyrin trial, there were no overall significant differences in average daily gain or feed efficiency. However, 2,000 ppm birds had significantly decreased abdominal fat deposition compared to controls (P ≤ 0.05), and the breast muscle deposition increased in a dose-response manner to the supplementation of monobutyrin (P ≤ 0.05). The combination trial tested 5 treatment groups: control, 500 ppm tributyrin + 500 ppm monobutyrin (5T5M), 500 ppm tributyrin + 500 ppm monobutyrin staggered (5T5Ms), 500 ppm tryibutyrin + 2,000 ppm monobutyrin (5T20M), or 500 ppm tributyrin + 2,000 ppm monobutyrin staggered (5T20Ms). In staggered groups, birds were fed tributyrin for one wk followed by 2 wk of monobutyrin, after which the feed was butyrate glyceride free. The non-staggered groups had constant inclusions levels through the 5 weeks. There were no significant differences in average daily gain or feed efficiency among groups. At 5 wk of age, all treatment groups except for 5T5Ms had significantly lower relative abdominal fat weight compared to control birds (P ≤ 0.05), although 5T5Ms birds demonstrated a trend for a decrease (P = 0.095). Relative breast muscle weight was significantly increased only in 5T5M birds over control birds at 5 wk of age (P ≤ 0.05). Serum biochemistry revealed significant changes in factors relating to muscle growth and fat deposition (P ≤ 0.05). These results indicate a consistent shift in lipid metabolism with the addition of butyrate glycerides and that the deposition of breast muscle may be highest with the incorporation of butyrate glycerides at a moderate level for the duration of development.

A genetically female brain is required for a regular reproductive cycle in chicken brain chimeras

Sexual differentiation leads to structural and behavioural differences between males and females. Here we investigate the intrinsic sex identity of the brain by constructing chicken chimeras in which the brain primordium is switched between male and female identities before gonadal development. We find that the female chimeras with male brains display delayed sexual maturation and irregular oviposition cycles, although their behaviour, plasma concentrations of sex steroids and luteinizing hormone levels are normal. The male chimeras with female brains show phenotypes similar to typical cocks. In the perinatal period, oestrogen concentrations in the genetically male brain are higher than those in the genetically female brain. Our study demonstrates that male brain cells retain male sex identity and do not differentiate into female cells to drive the normal oestrous cycle, even when situated in the female hormonal milieu. This is clear evidence for a sex-specific feature that develops independent of gonadal steroids.