High-energy diet enhances spermatogenic function and increases sperm midpiece length in fallow deer ( Dama dama ) yearlings

Abstract

Nutrition is a major factor involved in the sexual development of livestock ruminants. In the male, a high-energy diet enhances the reproductive function, but its effects on the underlying processes such as spermatogenic efficiency are not yet defined. Moreover, the possible changes in sperm size due to a supplemented diet remain poorly investigated. The main goal of this study was to evaluate whether a high-energy diet affects the spermatogenic activity, epididymal sperm parameters (concentration, morphology, morphometry and acrosome integrity) and blood testosterone levels in fallow deer yearlings. For this purpose, 32 fallow deer were allocated into two groups according to their diet: control (pasture) and experimental (pasture and barley grain) groups. Fallow deer from the experimental group showed a significant increase in the Sertoli cell function and sperm midpiece length, together with a higher testicular mass, sperm concentration and percentage of normal spermatozoa than the control group ( p < 0.05). We also found a tendency for higher blood testosterone levels in the animals fed with barley grain ( p = 0.116). The better sperm quality found in the experimental group may be related to their higher efficiency of Sertoli cells and to an earlier onset of puberty. The results of the present work elucidate the mechanisms by which dietary supplementation enhances the male sexual development and might be useful for better practices of livestock management in seasonal breeders.

Post‐mortem recovery, in vitro maturation and fertilization of fallow deer (Dama dama, Linnaeus 1758) oocytes collected during reproductive and no reproductive season

“…Nevertheless, other factors could influence the number of oocytes recovered per ovary such as different genetic background and availability of nutritional resources. In this sense, previous studies have found the nutrition affects the reproductive physiology in fallow deer (Enright, Spicer, Kelly, Culleton, & Prendiville, 2001; Ros‐Santaella, Kotrba, & Pintus, 2019). Unexpectedly, we found the number of oocytes per doe recovered during the breeding season was lower compared to the value observed during the breeding season (Zomborszky et al., 2004).…”

The hidden ageing costs of sperm competition

“…Although earlier studies assumed that sperm were particularly cheap to produce (see Dewsbury, 2005), the influence of resource availability on sperm production has been demonstrated in a wide spectrum of organisms. For instance, in fallow deer ( Dama dama ), a species in which females mate with several males during a given reproductive attempt (Briefer et al ., 2013), yearling males with a diet supplemented with protein and amino acids have larger testes, exhibit Sertoli cells – which play a key nutritional function during spermatogenesis – with higher workload capacities, higher concentrations of sperm within the epididymis and sperm with a longer midpiece than do non‐supplemented yearling males (Ros‐Santaella et al ., 2019). This positive effect of an enriched diet on sperm quantity and/or quality has also been repeatedly found in agronomy research (e.g.…”

“…Finally, experimental manipulations of the quantity of resources available in the environment would also provide relevant insights. As emphasised above, the allocation to ejaculate production increases with resource availability (Zhao et al ., 2017; Ros‐Santaella et al ., 2019). Therefore, for a given level of sperm competition perceived in the environment, we can predict that males should increase their allocation to post‐copulatory competition, at no or very limited costs in terms of ageing.…”

Spermatogenic Activity and Sperm Traits in Post-Pubertal and Adult Tomcats (Felis catus): Implication of Intra-Male Variation in Sperm Size

“…Similarly, on the one hand, we also found that round spermatids were the most abundant spermatogenic cells, while secondary spermatocytes were the most scarce in a tomcat’s testicular cytology [ 23 , 25 ]. This pattern is consistent across several species such as red deer ( Cervus elaphus ) [ 24 ], fallow deer ( Dama dama ) [ 26 ], alpaca ( Vicugna pacos ) [ 27 ], and gemsbok ( Oryx gazella ) [ 28 ]. On the other hand, in jaguars ( Panthera onca ), elongated spermatids are the most abundant spermatogenic cells [ 29 ].…”

“…At least 200 spermatogenic and Sertoli cells were counted per smear and classified according to the morphological criteria previously described in tomcat’s testicular cytology [ 23 , 25 ] ( Figure 2 ). The following spermatogenic indices were calculated, as previously described by Ros-Santaella et al [ 26 ]: Sertoli cell index (SEI), which is the percentage of Sertoli cells per total germ cells; spermatozoa–Sertoli index (SSEI), which is the ratio of sperm cells to Sertoli cells; meiotic index (MI), which is the ratio of round spermatids to primary spermatocytes and estimates the meiotic germ cell loss; ratio of elongated spermatids to round spermatids (ES/RS), which estimates the post-meiotic germ cell loss; ratio of elongated spermatids to total germ cells (ES/GC), which estimates the overall germ cell loss; ratio of round spermatids to Sertoli cells (RS/SC) and the ratio of elongated spermatids to Sertoli cells (ES/SC), which both estimate the Sertoli cell functionality; and the ratio of total germ cells to Sertoli cells (GC/SC), which estimates the workload capacity of Sertoli cells.…”