Tomás Landete-Castillejos

Maternal quality and differences in milk production and composition for male and female Iberian red deer calves (Cervus elaphus hispanicus)

Several theories predict a sex-biased investment either through unbalanced sex ratios in offspring or through differences in provisioning. According to them, one would expect an optimisation in indirect fitness, or else a compensation for increased mortality of one sex. In addition, biases in provisioning may also arise as a consequence of weight-dependent non-adaptive nutrient demands by offspring. This study examines milk provisioning and sex biases in offspring sex ratio together with maternal quality variables. Mothers of higher quality (weight and age) showed greater milk provisioning ability (in terms of production) resulting in greater calf weight gain. Mothers of sons produced greater yields of milk, milk protein, fat and lactose than mothers of daughters, and increased percentage of protein after controlling for higher male birth weight. In contrast, mothers of males did not differ from mothers of females in age or any body weight variables related to maternal quality. These results suggest that differences in milk production and composition for sons and daughters are rather a mechanism to optimise indirect fitness than a mechanism to compensate for increased mortality in male calves, or a consequence of greater weight-dependent nutrient demands by heavier male calves. Results also suggest that biases in milk provisioning may occur without biases in offspring sex ratio, and furthermore, in contrast to the prediction that biases should be relative to the mean investment of the population, that milk provisioning biases might not be relative.

Postmortem Assessment of Sperm Characteristics of the Red Deer During the Breeding Season

This study examined the effect of male age, time lapse between death of individual and collection of its sperm, breeding season (1993, 1995, or 1996), and testicle sampled (left or right) on the cell quality of spermatozoa obtained postmortem from the epididymis of red deer stags (Cervus elaphus hispanicus). A total of 142 sperm samples obtained from 71 free-ranging individuals shot during the breeding season were used to investigate these effects. The spermatozoa were obtained from the cauda epididymis of stags. Immediately after collection, an assessment was made of the proportion of motile spermatozoa (PM), normal morphology (PN), intact acrosomes (PIA), and the osmotic resistance degree of the plasmatic spermatozoa membrane as determined by the cell endosmosis test (E+). Gamete quality was influenced by both the age of the individuals and the lapse between death and collection of sperm (p < 0.001), whereas the year of collection and testicle sampled did not affect sperm quality. Sperm samples were classified in three groups: excellent, acceptable, or unacceptable, depending on the values achieved in the PM, PN, E+, and PIA variables. Acceptable samples had to achieve the following score: PM > 40%, PN > 40%, E+ > 40%, and PIA > 60%. Within this group, samples with a PM > 60% were classified as excellent. The percentage of samples classified as viable (strictly acceptable plus excellent) achieved 59.8% (85 out of 142). These results indicate that it is possible to obtain a remarkable percentage of viable sperm after the death of the deer. This finding might also be useful to obtain embryos of threatened species of wild ungulates.

The mechanical properties of red deer antler bone when used in fighting

SUMMARY We assessed the hydration state of antlers and its effect on antler mechanical properties compared with wet femur. Red deer antlers were removed from the head at various times, from a few days after velvet shedding till late in the season, and weighed weekly until after casting time. Antlers cut just after losing their velvet lost weight rapidly in the first few weeks, then settled down and changed weight very little, the latter changes correlating with air relative humidity. Antlers cut later showed little weight change at any time. The water content of cortical and trabecular parts of the contralateral antler was assessed after cutting. Most of the weight loss was from the cancellous, not the cortical, part of the antler. Wet and dry specimens from the antlers, and wet specimens from deer femora, were tested mechanically. Compared with wet bone, wet antler had a much lower modulus of elasticity and bending strength, but a higher work to fracture. Compared with wet bone, dry antler showed a somewhat lower Youngs modulus, but a considerably higher bending strength and a much higher work to fracture. The impact energy absorption of dry antler was much greater than that of wet bone. In red deer, the antler is effectively dry during its use in fights, at least in southern Spain. In addition, dry antler, compared with ordinary bone, shows mechanical properties that suit it admirably for its fighting function.

Milk intake and production curves and allosuckling in captive Iberian red deer, Cervus elaphus hispanicus

In two experiments, we compared milk intake (assessed by weighing calves before and after suckling) and milk production (by hand milking hinds) in Iberian red deer both when calves sucked their mothers together (group-suckling experiment) and when mother and offspring were isolated (isolation-suckling experiment). In both experiments, the general lactation curve for calves increased to a peak and then decreased (type I, standard lactation curve in mammals), whereas the curve for hinds decreased from the start (type II). However, in the experiment on group suckling, calves ingested 17.2% more milk than that produced by their mothers from weeks 6 to 20. In both isolation- and group-suckling experiments, hinds showed an overproduction of milk decreasing from weeks 1 to 5. This decreasing overproduction coincides with a similar trend in calf mortality reported in the literature and might thus be aimed at ensuring calves have sufficient nutrients when mortality is highest. In addition, allosuckling observations in the group-suckling experiment showed an inverse relationship between milk production and percentage of allosucking attempts. Allosucking attempts were also more frequent after the milk overproduction period. Both findings suggest that allosuckling is a response to compensate for a reduced maternal milk supply. Copyright 2000 The Association for the Study of Animal Behaviour.

Reproductive seasonality in female Iberian red deer (Cervus elaphus hispanicus)

This study characterized the seasonal pattern of luteal cyclicity in Iberian red deer (n=16), by measuring plasma progesterone concentrations in hinds (female red deer) twice per week from calving (May and June) 1996 until May 1997. In eight of these hinds we also examined plasma prolactin profiles to assess seasonal responses to photoperiod. Plasma progesterone concentration in the 16 hinds studied indicated that the reproductive pattern is seasonal, and lasts for 5.73 +/- 0.27 months. After calving, progesterone levels remained basal (no luteal activity) for several months, except in a hind that lost her calf just after calving, and thus did not have to suckle it. This hind showed two consecutive estrus cycles in the month following calving, which suggests that suckling has an inhibiting effect on the resumption of ovarian activity. These results also showed that as long as the hinds do not become pregnant, they show between 5 and 10 estrus cycles per reproductive season (8.06 +/- 0.35), ranging between 105 and 249 days from onset of the first cycle to end of the last one. Uninterrupted cycling lasted for 3.5-6.4 months (mean, 4.6 +/- 0.24). Cyclic luteal activity was found from October to February in all hinds, with a smaller, but notable proportion in September (56.25%) and March (68.8%), whereas it was negligible in the remaining period. Our results show a reproductive season similar to or longer than that recorded by other authors. Prolactin plasma concentrations showed a yearly trend following that of photoperiod, with peak concentrations from April to July, a decrease in August, minimal concentrations from September to February and a sharp increase in March.

Lactation under food constraints in Iberian red deer Cervus elaphus hispanicus

The plane of nutrition in deer may affect body condition and lactation in hinds and calf growth both through long-term density-dependent effects and by shortterm abiotically originated falls in food supply. Our study examines the effect of low nutrient availability after calving on lactation in captive Iberian red deer Cervus elaphus hispanicus. Twelve hinds and their calves were allotted to a food restricted (50–60% daily energy requirements) or a control group just after calving. Hinds in the food-restricted group showed a greater body mass loss, produced less milk and yield of milk fat, protein and lactose, and a different lactation curve shape, which resulted in reduced calf growth. However, the time course of lactation variables appeared to show a compensatory response up to week 4: a greater milk fat content in low-nutrition hinds than in the control group appeared to compensate for lower milk production, as neither calf nor hind mass differed from the control group, and lactation variables in both groups showed a standard lactation pattern. In contrast, as milk fat content fell below that of the control group after week 4, the low nutrition plane overcame a standard lactation pattern and groups differed in most variables (e.g. calf and hind mass and percentage of calf growth). Our results appear to show that deer mobilise body reserves in lactation to maintain offspring growth under temporary reductions in food intake, which may be a strategy of securing investment in current offspring at the expense of reproducing the following season.

Conservation of Cervus elaphus meat in modified atmospheres

This study examines the effect of three types of modified atmospheres, each with a different gas composition (A:40% CO(2)+60% N(2); B:80% CO(2)+20% O(2); C:80% CO(2)+20% N(2)), on the development of meat quality of Cervus elaphus in order to suggest a gas composition that best preserves this type of meat. Meat quality was assessed by examining pH, colour as L(∗)a(∗)b(∗) values, drip loss (DL), cooking loss (CL) and shear force (SF). In samples of group A, pH values tended to be higher in all storage periods than those packed with 80% CO(2) and significant differences (P<0.001) among the groups were found at 16 d of storage. Gas composition affected a(∗) and b(∗) parameters (P<0.001), in samples packed with O(2), the b(∗) values were higher than in other groups, while the opposite was true in a(∗) values. Similar values of DL and CL were observed for all treatments and both parameters increased over time. SF values decreased with ageing, with similar values observed for all treatments.

LAI estimation of natural pine forest using a non-standard sampling technique

Abstract Indirect methods to estimate the leaf area index (LAI) in forests have been less successful than the more costly direct (allometric) methods. Our aim was to find an indirect method to estimate LAI efficiently, using the LAI-2000, Plant Canopy Analyzer, in forest stands of Pinus halepensis . The direct LAI estimate of individual trees was carried out through destructive sampling. In forest stands, direct estimates were derived from the allometric relationship between leaf area per tree and diameter at breast height (DBH). Indirect estimates were conducted with a standard strategy (i.e., multiple readings per plot placing the sensor at sites selected systematically on a transect) and with our non-standard strategy consisting of reading at a single point per plot, standardising the distance and orientation from a subject tree to reduce variability. The non-standard sampling strategy was a procedure as effective and accurate as the indirect standard strategy (transects), but more labour-efficient. The indirect estimate of the LAI-STAND using the LAI-2000, with either strategy was unbiased. These results advocate the use of a non-standard strategy scattering the sampling points throughout the stand rather than concentrating all the effort on a few plots following a standard strategy and leaving the rest of the stand unchecked. Also, both the standard and the non-standard strategy yielded significant regression models to estimate forest stand parameters, which are labour expensive to measure using direct methods. Thus, the LAI-2000 could be used as a tool to estimate such parameters indirectly.

Biometrics, Testosterone, Cortisol and Antler Growth Cycle in Iberian Red Deer Stags (Cervus elaphus hispanicus)

In this article, we aimed to describe the changes related to mating season in red deer, especially those related to antler growth, body condition score, testosterone and cortisol. Antler growth was studied in 17 Iberian red deer males, including body weight, antler length, biometric measures and testosterone and cortisol determination during 15 months. Body weight, body condition score, thoracic perimeter (TP), neck perimeter (NL) and testicular diameter (TD) showed the highest values immediately before mating season (autumn), decreased during it and remained constant at winter. Antler growth lasted 158 days and produced antlers with a final length of 80.8 +/- 2.0 cm. Testosterone and cortisol showed seasonal changes with maximum values at September and May, respectively. Final antler size was related positively to cranial longitude, TP, NL, TD and body weight at casting time. No relationship between weight loss during precedent mating season and current antler size was found, but spring recovery weight was positively related to final antler size. Final length was related to the descent in testosterone values during previous mating season and to body weight before it. Spring recovery weight was related to relative weight loss during previous mating season. These results suggest that there is no relationship between the reproductive effort performed during one season and the next year size of the antler. In contrast, antler size was positively related to spring recovery weight, in the sense that those deer that recover a higher percentage of body weight at the early stages of antler growth develop higher antlers.

Effects of Nutritional Stress During Lactation on Immunity Costs and Indices of Future Reproduction in Iberian Red Deer (Cervus elaphus hispanicus)

Abstract Nutrition may affect the balance between immunity and traits such as reproduction or growth. This study examines the effect of low nutrient availability on immunity indices and lactation in captive Iberian red deer. Twelve hinds and their calves were allotted to a food-restricted (50–60% daily energy requirements) or a control group just after calving. Low calorie intake exerted a greater effect on the immunity of calves than on that of hinds. Whereas no difference was found for hinds, calves of the low intake group showed mean immunoglobulin (Ig) levels higher than those on a standard diet, which suggests that Ig level may indicate the level of fighting against pathogens. Serum indices of body condition in calves showed generally positive correlations with milk nutrient production. In contrast, Ig level within each group showed a pattern inverse to that of the other group for early lactation: in the standard diet group, the greater the milk nutrient produced and calf growth, the lower the Ig level; this relationship was inversed in the low-nutrition group. These results suggest that, on a standard diet, high Ig levels may indicate high levels of pathogen fighting paired to poorer body condition. Inversely, once the first barriers of innate immunity are surpassed, only those calves on the low-nutrition group with greater resources would be able to spend more resources to fight infection. Thus, low calorie intake might boost its slowing effect on growth by increasing the costs of infection fighting.